Journal of Oral Science & Rehabilitation No. 4, 2017

Journal of Oral Science & Rehabilitation No. 4, 2017

Editorial / About the Journal of Oral Science & Rehabilitation / Buccal plate reconstruction with an intentionally exposed nonresorbable membrane: 1 year after loading results of a prospective study / Periimplant soft-tissue and bone levels around dental implants with di erent neck designs and neck surface treatments: A retrospective cohort study with 3-year follow-up / Antimicrobial efficacy of mouthwashes containing zinc-substituted nanohydroxy- apatite and zinc L-pyrrolidone carboxylate on suture threads after surgical procedures / Multifactorial statistical analysis toward evaluation of MBL, PES and PI of a novel non- submerged implant to restore a single tooth: A 1-year prospective cohort study / Digital approach to the fabrication of a wax prototype for full-mouth rehabilitation of a worn dentition: A clinical report / Is there a justification for cone beam computed tomography for assessment of proximity of mandibular first and second molars to the inferior alveolar canal: A systematic review / Bringing science to the surface - An interview with Prof. Matthias Karl / Guidelines for authors / Imprint

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Journal of

Oral Science
&
Rehabilitation
I S S N 2 3 6 5 - 6 8 9 1 (Online)

Volume 3 — Issue 4/2017

I S S N 2 3 6 5 - 6 1 2 3 (Print)

Journal for periodontology, implant dentistry,
dental prosthodontics and maxillofacial surgery

[2] =>

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in alphabetical order as per October 2017.

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Editorial

Journal of

Oral Science
&
Rehabilitation
Clinical and experimental research provides us with the basic knowledge to support the procedures
that we apply in our daily practice. We are all aware that we should not use techniques that are not yet
supported by scientific evidence or use material that has not been sufficiently tested.
Clinical research gives us the information needed to confirm the validity of new clinical procedures
and whether a given device or biomaterial is able to render the expected results. However, to obtain
information on healing patterns, experimental research is crucial.
When writing an article or conducting a review for a scientific journal, we should assess materials
and methods carefully and whether the conclusions are congruent with the results. In research, to
evaluate the phenomenon under study, it is very important to select with accuracy the variables and
the methods to measure these variables. In addition, to eliminate possible biases that may lead to incorrect measurements and wrong conclusions, particular attention has to be paid to correct use of
randomization and calibration procedures. We need to apply these measures to reduce the risk of bias
and improve the quality of our research so that our results and interpretations may be relied on. This
improved quality will be useful for systematic reviews that are located at the top of the evidencebased medicine pyramid. However, it should be emphasized that systematic reviews would not exist
without the daily work of the researchers. As researchers, it is important that we apply proper procedures to reduce the risk of bias and to improve the quality of our methodology and data collection. If
we do not ensure this, systematic reviews will rely on few studies, few patients, low homogeneity regarding population, and poor standardization of methods and data, and the conclusions will thus not
be clinically relevant.

Dr. Daniele Botticelli
Co-Editor

Journal of
Oral Science & Rehabilitation

Volume 3 | Issue 4/2017

[4] =>

Content

3
Editorial
Dr. Daniele Botticelli
6
About the Journal of Oral Science & Rehabilitation
08
Roberto Luongo et al.
Buccal plate reconstruction with an intentionally exposed nonresorbable
membrane: 1 year after loading results of a prospective study
16
Natalia Ribes Lainez et al.
Periimplant soft-tissue and bone levels around dental implants with
different neck designs and neck surface treatments: A retrospective
cohort study with 3-year follow-up
24
Saverio Cosola et al.
Antimicrobial efficacy of mouthwashes containing zinc-substituted
nanohydroxyapatite and zinc L-pyrrolidone carboxylate on suture
threads after surgical procedures
32
Carlo Prati et al.
Multifactorial statistical analysis toward evaluation of MBL, PES and PI
of a novel nonsubmerged implant to restore a single tooth: A 1-year
prospective cohort sudy
42
Christian Brenes et al.
Digital approach to the fabrication of a wax prototype for full-mouth
rehabilitation of a worn dentition: A clinical report
48
Shahnawaz Khijmatgar et al.
Is there a justiﬁcation for cone beam computed tomography for
assessment of proximity of mandibular ﬁrst and second molars to the
inferior alveolar canal: A systematic review
58
Interview Prof. Matthias Karl
Bringing science to the surface
60
Guidelines for authors
62
Imprint — about the publisher

04 Volume 3 | Issue 4/2017

Journal of
Oral Science & Rehabilitation

[5] =>

l rights reserved.
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• Mirela Feraru • Tali Chackartchi • Tommie Van De Velde • Pablo Galindo-Moreno • Stavros
Pelekanos • Juan Arias Romero • Victor Clavijo • Anas Aloum • Gustavo Giordani. To learn more
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[6] =>

About

About
the Journal of Oral Science & Rehabilitation
The aim of the Journal of Oral Science & Rehabilitation is to promote rapid
communication of scientiﬁc information between academia, industry
and dental practitioners, thereby inﬂuencing the decision-making in
clinical practice on an international level.
The Journal of Oral Science & Rehabilitation publishes original and highquality research and clinical papers in the ﬁelds of periodontology, implant dentistry, prosthodontics and maxillofacial surgery. Priority is
given to papers focusing on clinical techniques and with a direct impact
on clinical decision-making and outcomes in the above-mentioned
ﬁelds. Furthermore, book reviews, summaries and abstracts of scientiﬁc
meetings are published in the journal.
Papers submitted to the Journal of Oral Science & Rehabilitation are subject to rigorous double-blind peer review. Papers are initially screened for
relevance to the scope of the journal, as well as for scientiﬁc content and
quality. Once accepted, the manuscript is sent to the relevant associate
editors and reviewers of the journal for peer review. It is then returned to
the author for revision and thereafter submitted for copy editing. The
decision of the editor-in-chief is made after the review process and is
considered ﬁnal.

About
Dental Tribune Science
Dental Tribune Science (DT Science) is an online open-access publishing
platform (www.dtscience.com) on which the Journal of Oral Science &
Rehabilitation is hosted and published.
DT Science is a project of the Dental Tribune International Publishing
Group (DTI). DTI is composed of the leading dental trade publishers
around the world. For more, visit

www.dental-tribune.com

06 Volume 3 | Issue 4/2017

Journal of
Oral Science & Rehabilitation

[7] =>

About

Benefits
of publishing in the journal for authors
There are numerous advantages of publishing in the Journal of Oral
Science & Rehabilitation:
– Accepted papers are published in print and as e-papers on
www.dtscience.com.
– Authors’ work is granted exposure to a wide readership, ensuring
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www.dtscience.com.
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– Authors can also post videos relating to their research, present
a webinar and blog on www.dtscience.com.

Subscription price
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Information for subscribers
The journal is published quarterly. Each issue is published as both a print
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Terms of delivery
The subscription price includes delivery of print journals to the recipient’s
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Copyright © Dental Tribune International GmbH. Published by Dental
Tribune International GmbH. All rights reserved. No part of this publication may be reproduced, stored or transmitted in any form or by any
means without prior permission in writing from the copyright holder.

Journal of
Oral Science & Rehabilitation

Volume 3 | Issue 4/2017

07

[8] =>

Intentionally exposed membrane

Buccal plate reconstruction with
an intentionally exposed nonresorbable
membrane: 1 year after loading results
of a prospective study
Abstract
Objective
Roberto Luongo,a Giuseppe Bianco,b Calogero Bugeac
& Marco Tallaricod
a

Ashman Department of Periodontology and Implant
Dentistry College of Dentistry, New York University,
New York, U.S.; private practice, Bari, Italy
b
Ashman Department of Periodontology and Implant
Dentistry College of Dentistry, New York University,
New York, U.S.; private practice, Rome, Italy
c
Private practice, Galatone, Italy
d
Aldent University, Tirana, Albania; private practice,
Rome, Italy

Corresponding author:
Dr. Marco Tallarico
Via di Val Tellina, 116
00151 Rome
Italy
T +39 328 075 8769
me@studiomarcotallarico.it

The aim of this study was to investigate the barrier effect of a highdensity polytetraﬂuoroethylene (d-PTFE) membrane left intentionally
exposed in post-extraction sockets grafted with an allograft biomaterial
and removed after 5 weeks.
Materials and methods

Forty-seven hopeless teeth were extracted. Residual sockets were
grafted with an allograft biomaterial and covered with a d-PTFE membrane. Six months later, 47 submerged implants were installed. Four
months later, implants were uncovered and a temporary restoration was
delivered. Outcomes were implant and prosthetic survival rate, complications, alveolar ridge width measurement, marginal bone loss (MBL)
and gingival recession. Follow-up ranged from 1 to 3 years. The buccal
plate was measured after tooth extraction (BPS), at implant placement
(BPW) and at implant uncovering/loading (BBT).
Results

How to cite this article:
Luongo R, Bianco G, Bugea C, Tallarico M. Buccal plate
reconstruction with an intentionally exposed
nonresorbable membrane: 1 year after loading results
of a prospective study.
J Oral Science Rehabilitation. 2017 Dec;3(4):8–14.

No deviation from the original protocol occurred. All of the implants were
osseointegrated. None of the prostheses failed and no complications
occurred during the follow-up. The mean BPS at the midpoint was
6.5 ± 1.5 mm (at the time of extraction; T0). At time of implant placement
(T 1), the mean BPW was 6.30 ± 1.30 mm, with a crestal reduction of
0.19 ± 0.34 mm (P = 0.0006). At implant uncovering/loading, the mean
BBT was 1.7 ± 0.5 mm. One year after loading (T3), periapical radiographs
revealed a mean MBL of 0.62 ± 0.16 mm, compared with T 1. One year
after initial loading there was no buccal gingival recession compared
with T0, with a mean soft-tissue creeping of 0.8 ± 0.2 mm.
Conclusion

Buccal plate reconstruction with an intentionally exposed nonresorbable
membrane is an effective and easy procedure for regeneration of a
resorbed buccal bone plate.
Keywords

Dental implants, biomaterials, guided bone regeneration, dense PTFE.
08 Volume 3 | Issue 4/2017

Journal of
Oral Science & Rehabilitation

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Intentionally exposed membrane

Introduction
A signiﬁcant 3-D remodeling of the bone crest,
especially horizontally, always occurs after the
extraction of a tooth.1 This makes it difficult to
insert an implant, especially in the frontal areas,
where residual bone thickness is fundamental
for optimal esthetic results. In order to reduce
this contraction, a socket preservation technique
entailing the insertion of a bone graft and of a
resorbable membrane inside the socket, followed after 4–6 months by the positioning of a
delayed implant, has usually been proposed.2, 3
However, such a technique does not always have
predictable results, especially when the buccal
plate of the alveolar socket is missing after tooth
extraction.
Guided bone regeneration (GBR) has been
proposed as a possible alternative for patients
with severe horizontal bone atrophy, to overcome the drawback of bone block techniques.4, 5
In order to protect the clot and prevent the invasion of the clot by nonosteogenic cells, maintaining an adequate biological space for the
regeneration of bone tissue, the use of either
nonresorbable or resorbable membranes has
been proposed.6 Expanded polytetraﬂuoroethylene (e-PTFE) membranes and resorbable
membranes classically require soft-tissue coverage or primary closure to prevent soft-tissue
ingrowth, bacterial contamination, infection,
membrane migration, early membrane degradation, and graft exposure. The major feature of
the e-PTFE membrane is macroporosity, which
is believed to enhance regeneration by improving
wound stability.7 Nevertheless, its main drawback is that an early bacterial infection can occur,
affecting the outcome of the regeneration.
High-density polytetrafluoroethylene
(d-PTFE) membranes offer an alternative to
e-PTFE or resorbable membranes.8–11 A d-PTFE
membrane is made of 100% pure medical-grade
bio-inert PTFE, which is nonporous, dense, nonexpanded and nonpermeable.3, 5 The thickness
of the various commercially available membranes ranges from 0.13 to 0.25 mm and their
low porosity ranges from 0.2 to 0.3 mm; e-PTFE
membranes have a similar thickness, but a
higher porosity (5–30 nm).12 The indications for
d-PTFE membranes are similar to those for
e-PTFE, but the different porosity of the ﬁrst
avoids any inﬂammation of the surrounding soft
tissue in case of accidental exposure.13 There is
limited clinical and histological evidence for the
use of d-PTFE membranes at present, with some

indications for guided tissue regeneration and
GBR, especially in immediate implants and fresh
extraction sockets.7
The aim of the present prospective study
was to investigate the barrier effect of a d-PTFE
membrane left intentionally exposed in postextraction sockets grafted with an allograft
biomaterial and removed after 5 weeks. This
study is reported in accordance with the
Strengthening the Reporting of Observational
Studies in Epidemiology statement for improving the quality of observational studies.14

Materials and methods
This prospective study was conducted in a private dental practice from February 2012 to
March 2016. Forty-three patients of both sexes
requiring 47 implant-supported single-crown
restorations to rehabilitate an esthetic area with
a hopeless tooth with an Elian type II socket
(facial soft tissue was present, but the buccal
plate was partially missing after extraction of
the tooth),15 aged 18 years or older and able to
sign an informed consent form, were enrolled
and treated consecutively. This was provided
that they fulﬁlled the inclusion criteria and gave
their written consent to take part in the study.
The buccal plate was deﬁned as partially missing
when the distance from the gingival margin to
the most coronal part of the buccal plate was
greater than 4 mm, even in only 1 of the 3 reference points (mesial, distal and midpoint), while
both the mesial, distal and the palatal bony walls
were present at a distance of less than 4 mm
from the palatal gingival margin.
The exclusion criteria were positive medical
findings (such as stroke, recent myocardial
infarction, severe bleeding disorder, uncontrolled diabetes, or cancer), psychiatric therapy,
pregnancy or nursing, smoking more than
10 cigarettes per day, untreated periodontitis,
acute or chronic infections of the adjacent tissue
or natural dentition, previous radiotherapy of
the oral and maxillofacial region within the last
5 years, absence of teeth in the opposing jaw,
severe clenching or bruxism, severe maxillomandibular skeletal discrepancy, and poor oral
hygiene (full-mouth bleeding and a full-mouth
plaque index of higher than or equal to 25%).
Patients were informed about the clinical procedures, the materials to be used, the beneﬁts,
potential risks and complications, as well as any
follow-up evaluations required for the clinical

Journal of
Oral Science & Rehabilitation

Volume 3 | Issue 4/2017 09

[10] =>

Intentionally exposed membrane

study. The medical history of the enrolled
patients was collected and study models were
produced. Preoperative radiographs, including
periapical and panoramic radiographs, and computed tomography or cone beam computed
tomography scans, were obtained for initial
screening and evaluation.
All procedures were conducted in accordance
with the Declaration of Helsinki of 1975, as
revised in 2013, for biomedical research involving human subjects. One clinician (RL) performed all of the surgical and prosthetic procedures, and one dental laboratory manufactured
all of the restorations.
Surgical and prosthetic protocols

The teeth were atraumatically extracted with
the aid of a periotome and atraumatic elevators
(PT1 and EPTSMS, Hu-Friedy Italy, Milan, Italy)
to reduce trauma to the bony walls (Fig. 1). After
accurate debridement of the socket with a
curette (CL866, Hu-Friedy), the distance from
the gingival margin to the residual buccal or palatal bone plate was measured with the aid of a
periodontal probe (PCPUNC15, Hu-Friedy,
Chicago, Ill., U.S.) in order to verify the degree
of bone crest resorption. If the distance was
more than 5 mm, a nonresorbable d-PTFE membrane (Cytoplast TXT-200, De Ore, Negrar, Italy),
adequately cut into an ice-cream cone shape,16
was introduced into the socket corresponding
to the area of the missing buccal plate, in order
to prevent soft-tissue proliferation. Subsequently, the d-PTFE membrane was inserted
into the socket with the narrower part facing the
buccal soft tissue and stabilized with a corticocancellous particulate allograft biomaterial
(Puros, Zimmer Dental, Carlsbad, Calif., U.S.),
placed inside the socket using a curved stainless-steel graft delivery syringe with a 4.5 mm
funnel opening (ACE Surgical Supply, Brockton,
Mass., U.S.; Fig. 2a). Then the wider part of the
membrane was overturned above the bone graft
and sutured with a 5-0 PTFE mattress suture
(Cytoplast, De Ore) to the palatal and buccal
mucosa, leaving it intentionally exposed (Fig.
2b). The patient was placed on an antibiotic regimen of 1 g of amoxicillin and clavulanic acid
(Augmentin, GlaxoSmithKline, Verona, Italy)
twice a day, starting the day before the surgery
and continuing 7 days after, and an analgesic
(ibuprofen, 600 mg) was prescribed if needed.
All of the patients were instructed to rinse with
0.12% chlorhexidine 3 times a day for 1 min after
10 Volume 3 | Issue 4/2017

brushing their teeth. No special indications were
recommended for the area of the graft.
After 5 weeks, the membrane was removed
without the need for anesthetic, leaving the
exposed site to heal by secondary intention
(Fig. 3). After 6 months, a crestal incision was
performed, then a full-thickness ﬂap was elevated, and an implant of 4.0 mm in width and
11.5 mm in length was placed according to the
manufacturer’s instruction (Full OSSEOTITE
Tapered Natural, Implant Innovations, Palm
Beach Gardens, Fla., U.S.; Fig. 4). The implant
was submerged and the ﬂap was sutured using
a resorbable suture (4-0; Vicryl, Ethicon, Ohio,
U.S.), obtaining a primary closure healing. After
4 months of healing, the implant was uncovered
and the provisional prosthesis was immediately
delivered. Four months later, the definitive
metal-free crown was delivered and the occlusion was adjusted (Fig. 5). The patients were
enrolled in a strict hygiene program and were
followed up to 3 years after initial loading.
The primary outcome measures were the
success rates of the implants and prostheses
and any surgical and prosthetic complications
that occurred during the entire follow-up. An
independent blinded assessor recorded all of the
measurements and collected the related data
according to the following criteria:
– An implant was considered a failure if it presented with any mobility, tested by tapping or
rocking the implant head with a hand instrument and/or any signs of radiolucency and/or
fracture on an intraoral radiograph taken with
the paralleling technique strictly perpendicular to the implant–bone interface. The implant
stability was assessed at initial loading and at
each follow-up.
– A prosthesis was considered a failure if it
needed to be replaced with a different type of
prosthesis.
– Complications: Any biological (pain, swelling,
suppuration, etc.) and/or mechanical (fracture
of the framework and/or the veneering material, screw loosening, etc.) complication was
considered.
The secondary outcome measures were dimensional changes in the alveolar ridge width, marginal bone level changes and gingival recession.
– The alveolar ridge width was measured to the
nearest millimeter using a periodontal probe
(PCPUNC156, Hu-Friedy) at the time of tooth
extraction (T 0 ), at implant placement
(6 months later; T 1), and at the time of implant

Journal of
Oral Science & Rehabilitation

[11] =>

Intentionally exposed membrane

Figs. 1a & b

Figs. 1a–c
Clinical view of the central
incisor before (a,b) and after
extraction (c).

a

Figs. 2a & b
Allograft inserted into the
socket after d-PTFE
membrane placement (a)
and suturing (b) at T0.

b

Fig. 1c

Figs. 3a & b
Membrane after 5 weeks (a).
Well-vascularized osteoid
tissue was evident after
removal (b).
Figs. 4a & b
Implant placement at T1: The
ridge appeared well formed
(a), and the implant could be
placed in an ideal position (b).

c
Figs. 2a & b

a

b

Figs. 3a & b

a

b

Figs. 4a & b

a

b

uncovering/loading (4 months later; T2). The
same clinicians who performed the tooth
extractions and implant placement performed
all of the measurements as follows: After tooth
extraction (T0), the buccolingual dimension of
the alveolar crest was measured from the inner

part of the buccal gingival margin to the inner
part of the palatal soft tissue at the mesiodistal midpoint of the socket (BPS), 3 mm subgingivally, using a periodontal probe (PCPUNC 15;
Fig. 6). Six months later, at (T 1), a crestal incision was done and a full-thickness ﬂap was

Journal of
Oral Science & Rehabilitation

Volume 3 | Issue 4/2017 11

[12] =>

Intentionally exposed membrane

Figs. 5a & b

Figs. 5a & b
The ﬁnal restoration delivery
at T2 showed a good esthetic
result (a) and marginal
periimplant bone preserved
at T3 (b).

elevated in order to expose the edentulous
ridge. Then the alveolar ridge thickness was
measured from the buccal to the palatal side
at the mesiodistal midpoint (BPW), as previously described (Fig. 7). Four months later, at
(T2), the horizontal width of the ridge was measured buccally, starting from the outer part of
the implant platform (BBT; Fig. 8).
– Marginal bone level changes were assessed
using intraoral digital periapical radiographs
taken with the paralleling technique at (T1) and
1 year after loading (T3), using a customized
holder. The radiographs were accepted or
rejected for evaluation based on the clarity of
the implant threads. All readable radiographs
were viewed in an image analysis program
(Kodak Digital Imaging Software, Version
6.11.7.0, Eastman Kodak, Rochester, N.Y., U.S.)
on a 24-in LCD screen (iMac, Apple, Cupertino,
Calif., U.S.) and evaluated under standardized
conditions (ISO 12646:2004). The software
was calibrated for every image using the known
implant diameter or length. The distance from
the most coronal margin of the implant collar
and the top of the bone crest was taken as marginal bone level. The average radiographic
values of the mesial and distal measurements
were taken for each implant at the time of
implant placement and 6 months later. The
difference between the marginal bone levels
at various time points was taken as marginal
bone loss (MBL). An independent radiologist
performed all of the bone measurements.
– Gingival recession was evaluated using a reference line connecting the midfacial gingival
level of the 2 adjacent teeth. The changes in the
gingival margin of the implant restoration were
evaluated before extraction (T0) and at T3.
12 Volume 3 | Issue 4/2017

All data analysis was carried out according to a
pre-established analysis plan using software
(IBM SPSS Statistics for Macintosh, Version
22.0, IBM, Armonk, N.Y., U.S.). Descriptive analysis was performed using mean and standard
deviation. Comparison of the means was performed by paired tests. A biostatistician with
expertise in dentistry analyzed the data.

Results
In total, 47 teeth were extracted in 43 patients,
26 women and 17 men, with a mean age of
54 years (Table 1). At the last follow-up, no
dropout and no deviation from the original
protocol occurred. All 47 implants were osseointegrated and none of the prostheses failed.
The follow-up ranged from a minimum of
1 year to a maximum of 3 years after loading.
In all of the treated cases, there was no
dehiscence of the buccal or palatal portion of
the implant at the moment of its exposure.
There was no site infection either before or
after the removal of the nonresorbable membrane, and no patient presented with edema
or ecchymosis post-implant surgery.
The mean BPS at the midpoint was
6.5 ± 1.5 mm at T0. At T 1, the mean BPW was
6.30 ± 1.30 mm, with a crestal reduction of
0.19 ± 0.34 mm (P = 0.0006), while at T2, the
mean BBT was 1.7 ± 0.5 mm. At T3, periapical
radiographs revealed a marginal bone loss of
0.62 ± 0.16 mm in the area surrounding the
implant, compared with T0. At T 3 , a mean
soft-tissue gain of 0.8 ± 0.2 mm was recorded,
with no buccal gingival recession compared
with T0.

Journal of
Oral Science & Rehabilitation

[13] =>

Intentionally exposed membrane

Fig. 6

Table 1

Fig. 7

Tooth

No.

Maxillary central incisor

Maxillary lateral incisor

Maxillary canine

Maxillary ﬁrst premolar

Maxillary second premolar

Mandibular central incisor

Mandibular canine

Mandibular ﬁrst premolar

Mandibular second premolar

Discussion
This study has presented the results of a new
technique for the spontaneous regeneration of
the missing buccal plate of a dental socket that
avoids the ingrowth of soft tissue inside it and
regenerates the previously resorbed buccal cortical bone. This technique may avoid invasive
further regenerative techniques, thus notably
reducing treatment time without impairing the
esthetic results, the predictability of the implant
treatment or patient satisfaction.
A limiting situation for post-extraction
implants, especially in areas of high esthetic
concern, is the resorption of the buccal bone
plate, which is fundamental for soft-tissue stability in the area surrounding the ﬁxture and
therefore for long-term esthetic results. The
reconstruction of such a bone wall almost
always requires an additional regenerative surgery, usually invasive for the patient, and precedes the prosthetically guided insertion of an
implant. The use of a nonresorbable membrane
intentionally left exposed inside the socket and
removed after 4–6 weeks seems to work as a
barrier in the separation of the soft tissue from

Fig. 8

the bone graft.17 The removal of the membrane
after 4–6 weeks seems to give sufficient time
to seclude ﬁbroblasts from the gingival ﬂap and
to allow inside the socket the differentiation of
mesenchymal cells into osteoblasts, leading
then to bone. In a histological human study, a
biopsy, taken at the moment of removal of a
d-PTFE membrane left intentionally exposed for
28 days before, demonstrated the absence of
epithelial tissue over a dense connective tissue
matrix.12 This ﬁnding indicates that this connective tissue seems to be a well-vascularized osteoid matrix that needs some more maturation
time to become a mineralized tissue and allow
placement of an implant.18 This period can last
from 3 to 6 months, depending on the size of the
defect and the biomaterial used as a graft.
In another histological study, a combination
of 70% mineralized and 30% demineralized cortical allograft material placed in a post-extraction
socket together with a d-PTFE membrane intentionally left exposed was compared with a group
for which only a mineralized allograft material
was used. The biopsy showed increased vital
bone formation (36.16%) and a reduced residual
graft (18.24%) compared with the 100% mineralized bone allograft group (24.69% and 27.04%,
respectively).19
In the present study, no infection of either
the surrounding soft tissue or of the underlying
graft was experienced owing to the low porosity
of the d-PTFE membrane, which does not allow
bacterial contamination. The nanoporosity of
the d-PTFE membrane is about 0.2–0.3 μ, too
small for the penetration of a bacterium, the size
of which is about 5 μ. This was conﬁrmed by a
histological study in which a membrane,
removed after 21 days, did not show any bacterial cell on the inferior border or surface.20

Journal of
Oral Science & Rehabilitation

Volume 3 | Issue 4/2017 13

Fig. 6
BPS: the distance from the
inner part of the buccal
gingival margin to the inner
part of the palatal soft
tissue at the mesiodistal
midpoint of the socket 3 mm
subgingivally at T0.
Fig. 7
BPW: the alveolar ridge
thickness from the buccal
to the palatal side at the
mesiodistal midpoint at T1.
Fig. 8
BBT: the horizontal width of
the ridge measured from
the outer part of the implant
platform to the buccal bone
at T2.
Table 1
Extracted teeth.

[14] =>

Intentionally exposed membrane

Another important result of this study is the
regeneration of the most coronal part of the
buccal plate with the combination of the icecream cone membrane technique and a nonresorbable membrane intentionally left exposed.
The results of this study have shown that minimal
crestal resorption occurs even if part of the buccal
plate is missing. The minimal crestal resorption
allows ideal implant placement with the presence
of about 2 mm of residual buccal bone, fundamental to support the soft-tissue margins, avoiding in this way gingival recession. These results
seem to be stable even 6 months after crown
placement with creeping of the soft tissue on the
buccal side compared with the initial situation.
However, further histological studies are needed
to validate these promising clinical results.

Conclusion
Buccal plate reconstruction with an intentionally
exposed nonresorbable membrane is an effective
and easy procedure for regeneration of a
resorbed buccal bone plate, especially after tooth
extraction in the esthetic zone, where the stability of the periimplant tissue is fundamental.

Competing interests
The authors declare that they have no conﬂict
of interest regarding the materials used in the
present study.

References
1.
Tallarico M, Xhanari E, Pisano M, De Riu G,
Tullio A, Meloni SM. Single post-extractive
ultra-wide 7 mm-diameter implants versus
implants placed in molar healed sites after
socket preservation for molar replacement:
6-month post-loading results from a
randomised controlled trial.
→ Eur J Oral Implantol.
2016 Oct;9(3):263–75.

7.
Carbonell JM, Martín IS, Santos A, Pujol A,
Sanz-Moliner JD, Nart J.
High-density polytetraﬂuoroethylene
membranes in guided bone and tissue
regeneration procedures: a literature
review.
→ Int J Oral Maxillofac Surg.
2014 Jan;43(1):75–84.

2.
Canullo L, Wiel Marin G, Tallarico M,
Canciani E, Musto F, Dellavia C.
Histological and histomorphometrical
evaluation of postextractive sites grafted
with mg-enriched nano-hydroxyapatite: a
randomized controlled trial comparing 4
versus 12 months of healing.
→ Clin Implant Dent Relat Res.
2016 Oct;18(5):973–83.
3.
Tallarico M, Xhanari E, Pisano M, Gatti F,
Meloni SM. Molar replacement with 7 mm
wide diamieter implants: to place the
implant immediately or to wait 4 months
after socket preservation? 1 year loading
results from a randomized controlled trial.
→ Eur J Oral Implantol.
2017 Sep;10(2):169–78.
4.
Buser D, Ingimarsson S, Dula K, Lussi A,
Hirt HP, Belser UC. Long-term stability of
osseointegrated implants in augmented
bone: a 5-year prospective study in
partially edentulous patients.
→ Int J Periodontics Restorative Dent.
2002 Apr;22(2):109–17.
5.
Urban IA, Jovanovic S, Lozada JL. Vertical
ridge augmentation using guided bone
regeneration (GBR) in three clinical
scenarios prior to implant placement: a
retrospective study of 35 patients 12 to
72 months after loading.
→ Int J Oral Maxillofac Implants.
2009 May-Jun;24(3):502–10.

6.
Urban IA, Caplanis N, Lozada JL.
Simultaneous vertical guided bone
regeneration and guided tissue
regeneration in the posterior maxilla
using recombinant human plateletderived growth factor: a case report.
→ J Oral Implantol.
2009 Oct;35(5):251–6.

8.
Waasdorp J, Feldman S. Bone regeneration
around immediate implants utilizing a
dense polytetraﬂuoroethylene membrane
without primary closure: a report of
3 cases.
→ J Oral Implantol.
2013 Jun;39(3):355–61. Epub 2011 Sep 9.
9.
Hoffmann O, Bartee BK, Beaumont C,
Kasaj A, Deli G, Zaﬁropoulos GG. Alveolar
bone preservation in extraction sockets
using non-resorbable dPTFE membranes:
a retrospective non-randomized study.
→ J Periodontol.
2008 Aug;79(8):1355–69.
10.
Barber HD, Lignelli J, Smith BM, Bartee
BK. Using a dense PTFE membrane
without primary closure to achieve bone
and tissue regeneration.
→ J Oral Maxillofac Surg.
2007 Apr;65(4):748–52.

11.
Monteiro AS, Macedo LG, Macedo NL,
Balducci I. Polyurethane and PTFE
membranes for guided bone regeneration:
histopathological and ultrastructural
evaluation.
→ Med Oral Patol Oral Cir Bucal.
2010 Mar;15(2):e401–6.
12.
Laurito D, Cugnetto R, Lollobrigida M,
Guerra F, Vestri A, Gianno F, Bosco S,
Lamazza L, De Biase A. Socket preservation
with d-PTFE membrane: histologic
analysis of the newly formed matrix at
membrane removal.
→ Int J Periodontics Restorative Dent.
2016 Nov/Dec;36(6):877–83.
13.
Bartee BK. Evaluation of a new
polytetraﬂuoroethylene guided tissue
regeneration membrane in healing
extraction sites.
→ Compend Contin Educ Dent.
1998 Dec;19(12):1256–8, 1260, 1262–4.
14.
Elm von E, Altman DG, Egger M, Pocock
SJ, Gotzsche PC, Vandenbroucke JP;
STROBE Initiative. Strengthening the
Reporting of Observational Studies in
Epidemiology (STROBE) statement:
guidelines for reporting observational
studies.
→ BMJ.
2007 Oct 20;335(7624):806–8.
15.
Elian N, Cho SC, Froum S, Smith RB,
Tarnow DP. A simpliﬁed socket
classiﬁcation and repair technique.
→ Pract Proced Aesthet Dent.
2007 Mar;19(2):99–104; quiz 106.
16.
Tan-Chu JH, Tuminelli FJ, Kurtz KS, Tarnow
DP. Analysis of buccolingual dimensional
changes of the extraction socket using the
“ice cream cone” ﬂapless grafting
technique.
→ Int J Periodontics Restorative Dent.
2014 May-Jun;34(3):399–403.

14 Volume 3 | Issue 4/2017

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17.
Bartee BK. A simpliﬁed technique for ridge
preservation after tooth extraction.
→ Dent Today.
1995 Oct;14(10):62–7.
18.
Beck TM, Mealey BL. Histologic analysis of
healing after tooth extraction with ridge
preservation using mineralized human
bone allograft.
→ J Periodontol.
2010 Dec;81(12):1765–72.
19.
Borg TD, Mealey BL. Histologic healing
following tooth extraction with ridge
preservation using mineralized versus
combined mineralized-demineralized
freeze-dried bone allograft: a randomized
controlled clinical trial.
→ J Periodontol.
2015 Mar;86(3):348–55.
20.
Krauser JT. High-density PTFE
membranes: uses with root-form implants.
→ Dent Implantol Update.
1996 Sep;7(9):65–9.

[15] =>

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[16] =>

Periimplant soft-tissue and bone levels with different implant neck designs

Periimplant soft-tissue and bone levels
around dental implants with
different neck designs and neck surface
treatments: A retrospective
cohort study with 3-year follow-up
Abstract
Objective
Natalia Ribes Lainez,a Alba Monreal Bello,a
María Ángeles Fuster Torres,a David Peñarrocha Oltraa
& Miguel Peñarrocha Diagoa
a

Stomatology Department, Faculty of Medicine and
Dentistry, University of Valencia, Valencia, Spain

The objective of the study was to assess the inﬂuence of the implant neck
designs and neck surface treatments on periimplant tissue health and
radiographic bone loss after 3 years of functional loading of implants
with the same body and prosthetic connection.
Materials and methods

Corresponding author:
Dr. David Peñarrocha Oltra
Cirugía Bucal. Clínicas Odontológicas
C/Gascó Oliag, 1
46021 Valencia
Spain
T +34 963 86 4144
david.penarrocha@uv.es
How to cite this article:
Ribes Lainez N, Monreal Bello A, Fuster Torres MA,
Peñarrocha Oltra D, Peñarrocha Diago M. Periimplant
soft-tissue and bone levels around dental implants
with different neck designs and neck surface treatments:
A retrospective cohort study with 3-year follow-up.
J Oral Science Rehabilitation. 2017 Dec;3(4):16–23.

A retrospective cohort study was carried out in the Oral Surgery and
Implantology Unit of the University of Valencia, Valencia, Spain. Patients
treated with implants presenting a neck design without microthreads
and a 1.5 mm machined surface and implants with a 0.7 mm machined
surface and microthreads with a rough surface with a minimum of 3 years
of follow-up were included. Probing pocket depth, bleeding on probing,
presence of mucositis and width of keratinized mucosa were assessed
3 years after prosthesis placement. Marginal bone loss was measured
in intraoral radiographs by calculating the difference between the measurements at the prosthesis placement and 3 years after loading.
Results

The ﬁnal sample consisted of 27 partially edentulous patients with a total
of 51 dental implants. No signiﬁcant differences were observed on evaluating probing pocket depth (P = 0.195), bleeding on probing (P = 0.524),
presence of mucositis (P = 0.916), width of keratinized mucosa (P = 0.435)
and marginal bone loss (P = 0.217) between both groups.
Conclusion

Within the limitations of the present investigation, implant neck designs
and neck surface treatments were not signiﬁcantly related to periimplant
tissue health and radiographic bone loss after 3 years of follow-up.
Keywords

Periimplant hard tissue, periimplant soft tissue, radiology, CT imaging,
clinical research, clinical trials.
16 Volume 3 | Issue 4/2017

Journal of
Oral Science & Rehabilitation

[17] =>

Periimplant soft-tissue and bone levels with different implant neck designs

Introduction
Bone loss after implant integration and through
time of function usually begins at the neck and
spreads to the ﬁrst thread of the body or to the
ﬁrst contact between the bone and the rough
surface of the implant,1 and can be divided into
2 different phases depending on the time of
occurrence. 2–5 The first, early bone loss, is
related to re-entry surgery after the healing
time or prosthetic connection,6 and the second,
late bone loss, emerges during the time of
implant and prosthesis function.4, 7, 8 Criteria for
evaluation of implant success are generally
based on clinical and radiological aspects, such
as probing depth, implant mobility and periimplant bone changes.9 It has been reported that
the criteria for successful implant therapy
include a median marginal bone loss of
< 1–1.5 mm during the ﬁrst year, followed by an
annual rate of vertical bone loss of ≤ 0.2 mm.10
In the last few decades, it has been suggested that marginal bone loss is dependent on
several factors, such as the implant neck surface design1, 4, 11–13 and characteristics.14, 15 It has
been proposed that bone retention elements
such as microthreads and a rough surface at
the implant neck might help stabilize the marginal bone.1, 12, 16, 17 Although the conventional
smooth implant neck allows the least accumulation of plaque,18, 19 several studies have evaluated marginal bone loss according to the
implant neck involved—machined implant
necks and rough necks with microthreads—and
have shown more marginal bone loss around
these implants compared with implants with a
rough surface topography at the implant
neck.4, 12, 13, 20 The relatively smooth, machined
coronal portion is designed to end slightly
above the gingival margin of the periimplant
soft tissue, thus making the microgap or interface between implant and restoration easily
accessible for oral hygiene and resulting in a
supragingival location of the crown margin. 21
Lang et al. in a consensus report concluded that
prospective controlled studies on the effects
of different implant designs and surfaces had
demonstrated that marginal bone levels were
generally well preserved after installation of
the dental prosthesis (at least for ﬁxed restorations) on a variety of implant types (cumulative bone loss: < 0.5 mm after 3 years).11 However, these studies had a 1-year follow-up and
there are no clinical studies comparing the
long-term inﬂuence of different designs and

surface treatments of implant necks on periimplant tissue. The purpose of this study was to
assess the effect of the implant neck designs
and neck surface treatments on periimplant
tissue health and radiographic bone loss after
3 years of functional loading of implants with
the same body and prosthetic connection but
different neck designs.

Materials and methods
Study design and sample

A retrospective cohort study was carried out in
the Oral Surgery and Implantology Unit of the
University of Valencia, Valencia, Spain, between
September 2015 and December 2016. This study
complied with the ethical principles for medical
research involving human subjects established
in the Declaration of Helsinki of 1975, as revised
in 2013, of the World Medical Assembly. All of
the patients received information about the
study and were asked to sign a written informed
consent form before taking part. The study
design was approved by the ethics board of the
University of Valencia (approval number:
H1467620442582).
Patients who had received single or partial
prosthetic rehabilitations on TSA or TSA
Advance implants (Phibo, Barcelona, Spain), had
a minimum of 3 years of follow-up and who
agreed to participate in the study and signed an
informed consent were included. Patients who
had undergone bone grafting procedures (block
bone grafts or guided bone regeneration), had
immediate post-extraction implants, had systemic diseases, were undergoing drug treatments capable of affecting gingival health, or
had a history of bisphosphonate use during control visits, as well as pregnant or nursing women
and patients with missing information, were
excluded. Patients were classiﬁed into 2 cohorts
according to the implant design:
– group A (TSA): patients treated with implants
presenting a neck design without microthreads, with a 1.5 mm machined surface and
an internal connection and without platform
switching (Fig. 1a); and
– group B (TSA Advance): patients treated with
implants presenting a neck design with a
0.7 mm machined surface and microthreads
with a rough surface and an internal connection and without platform switching (Fig. 1b).

Journal of
Oral Science & Rehabilitation

Volume 3 | Issue 4/2017 17

[18] =>

Periimplant soft-tissue and bone levels with different implant neck designs

Figs. 1a & b

a

Figs. 1a & b
Macrodesign of (a) TSA and
(b) TSA Advance implants.

b

Surgical procedure

The surgery was performed under local anesthesia with 4% articaine with 1:100,000 epinephrine (Inibsa, Lliçà de Vall, Spain). A crestal
incision was made, and a full-thickness mucoperiosteal ﬂap was raised. The drilling sequence
recommended by the manufacturer was followed. Implants were placed at a torque of 35 N
and positioned with the limit between rough
and polished surfaces at crestal level. Suturing
was carried out with 4-0 sutures (Supramid, B.
Braun, Barcelona, Spain).
All of the patients received postoperative
treatment: 500 mg of amoxicillin (Clamoxyl,
GlaxoSmithKline, Madrid, Spain) 3 times daily
for 7 days, 600 mg of ibuprofen (Bexistar,
Bacino, Barcelona, Spain) to be taken as
needed, a 0.12% chlorhexidine mouthwash
(GUM, Sunstar, Chicago, Ill., U.S.) twice daily
for 2 weeks and brushing with a chlorhexidine
toothpaste. The sutures were removed 8–10
days after surgery.
Data collection and follow-up

All of the surgeries were carried out by 1 experienced surgeon (MPD) and control visits were performed by 2 trained and calibrated clinicians at
prosthesis placement (T0) and at 6 and 12 months
and 3 years after prosthesis placement (T1).
The following variables were collected retrospectively: sex, age, smoking habit (< 10 cigarettes/
day, 10–20 cigarettes/day, > 20 cigarettes/day),
implant diameter and length, implant position
(anterior, premolar or molar), arch (maxilla or
mandible) and antagonist teeth (natural, implant,
18 Volume 3 | Issue 4/2017

absent). A millimetric calibrated periodontal
probe (Hawe Neos Probe 1395, Hawe, U.K.) was
used to assess the following clinical variables:
– probing pocket depth (PPD), measured from
the gingival margin to the deepest part of the
periimplant pocket, at 6 locations per implant
(mesiobuccal, buccal, distobuccal, mesiolingual/-palatal, lingual/palatal and distolingual/-palatal) choosing the largest value;
– bleeding on probing (BoP);
– presence of mucositis, understood as inﬂammation of the periimplant mucosa without
progressing to crestal bone loss;22 and
– width of keratinized mucosa in the buccal and
lingual region.
Intraoral radiographs were used to measure
marginal bone loss. Radiographic exploration
was carried out using the intraoral XMind
system (Groupe Satelec-Pierre Rolland, Bordeaux, France) and the RVG intraoral digital
sensor (Kodak Dental System, Atlanta, Ga., U.S.).
In order to reproduce the X-ray angles in posterior reviews, XCP positioners were used
(DENTSPLY, Des Plaines, Ill., U.S.), placing the
guide bar parallel to the direction of the X-ray
beam and perpendicular to the digital sensor.
All of the measurements were carried out by
2 examiners (different from the surgeon), who
were initially calibrated to evaluate the interexaminer error using the Dahlberg formula and
coefficient of variation. Each examiner measured
30 radiographs to evaluate the interexaminer
error. The error according to Dahlberg’s test
ranged between 0.63 and 0.93 mm for the various parameters and the coefficient of variation
between 5.2% and 6.4%.

Journal of
Oral Science & Rehabilitation

[19] =>

Periimplant soft-tissue and bone levels with different implant neck designs

Figs. 2a & b

Figs. 2c & d

Marginal bone loss was measured with the software ImageJ (National Institute of Health, Md.,
U.S.) to process JPG ﬁles as obtained from intraoral radiographs. Two reference points were
marked on each implant at the implant–
prosthesis interface and joined with a line representing height 0. Two vertical lines were
traced perpendicular to the 0 line up to the ﬁrst
mesial and distal bone–implant contacts
(Figs. 2a & b). Differences between these perpendicular lines in radiographs taken at the different time points (T0 and T 1) were used to calculate bone loss. The highest difference value
was chosen between the mesial and the distal
values. A line was traced across the implant
diameter (Figs. 2c & d) with the objective of calibrating the periapical radiograph measurements, knowing the true width of the implant.

of interest were periimplant tissue health and
radiographic bone loss after 3 years of functional loading.
A descriptive analysis of the parameters
was performed. Sample distribution of bone
loss was assessed, and due to lack of adjustment to normal distribution and dependence
of observations, the corresponding nonparametric tests were applied: method for longitudinal data of Brunner and Langer, providing an
analysis of variance statistic. Generalized estimating equations models were estimated to
analyze the probability of the neck design
affecting the various clinical variables through
the Wald chi-squared statistic. For the variables
BoP and presence of mucositis, a binary logistic regression model was estimated. For PPD
and width of keratinized mucosa, an ordinal
logistic regression model was estimated. The
statistical analysis was performed using SPSS
Statistical analysis
(statistical package for Microsoft Windows,
The principal predictor variable was the implant Version 15.0, SPSS, Chicago, Ill., U.S.) and R
neck designs and neck surface treatments software (Version 2.15.0, R Foundation for Sta(group A and group B). The outcome variables tistical Computing, Vienna, Austria). The

Journal of
Oral Science & Rehabilitation

Volume 3 | Issue 4/2017 19

Figs. 2a–d
Adimensional measurements
of marginal bone loss (a) at
prosthesis placement and
(b) after 3 years of follow-up.
Adimensional measurements
across the implant diameter
with the objective of
calibrating the bone level
measurements, knowing the
true width of the implant:
calibration of (c) the prosthesis
placement and (d) the 3-year
follow-up radiographs.

[20] =>

Periimplant soft-tissue and bone levels with different implant neck designs

signiﬁcance level was set at P < 0.05. The statistical methodology, with a conﬁdence level of
95% and the median effect size to detect
f = 0.25, reached a power of 0.81 for the contrast of the interaction effect (homogeneity of
bone loss in the groups).

Results
Fifty-ﬁve patients fulﬁlled the inclusion criteria. Patients who had undergone guided bone
regeneration (n = 9), had immediate implants
(n = 3), had missing information (n = 8) or failed
to attend control visits (n = 6) were excluded.
The ﬁnal sample consisted of 27 partially edentulous patients, 12 women and 15 men (mean
age: 63.5 ± 11.6), with a total of 51 dental
implants: 13 patients with 28 implants (group
A) and 14 patients with 23 implants (group B).
In group A, 22% were smokers, and in group
B, 44%. The implant sample was homogeneous regarding the implant diameter, length
and position, arch and antagonist dentition
(Table 1).
No signiﬁcant differences were observed
on evaluating clinical variables (Table 2).
Higher PPD was measured in group B
(5.3 ± 0.9 mm) compared with group A
(4.8 ± 1.4 mm), with no statistically signiﬁcant
differences (P = 0.195). Group A showed lower
BoP (47.1%) compared with group B (60%),
although the odds ratio suggested an increased
BoP risk with a TSA Advance implant (+27%),
but there was insufficient statistical evidence
to conclude a true effect (P = 0.524). Mucositis was present in 14.3% in group B and 12.5%
in group A, and the odds ratio suggested a
higher risk of mucositis with a TSA Advance
implant (14%), with no statistically signiﬁcant
differences between the groups (P = 0.916).
The higher score on width of keratinized
mucosa was found in group A (3.50 ± 2.44 mm)
in comparison with group B (2.7 ± 2.4 mm);
however, no statistically signiﬁcant difference
was found (P = 0.435). The mean radiographic
marginal bone loss with the TSA implants was
0.57 ± 0.55 mm (range: 0.00–2.10 mm) and
with the TSA Advance implants was
0.46 ± 0.49 mm (range: 0.00–1.61 mm), and
the median was 0.47 mm for the TSA implants
and 0.25 mm for the TSA Advance implants
(Table 3). Despite the greater marginal bone
loss around TSA implants, no statistically signiﬁcant differences were observed (P = 0.217).
20 Volume 3 | Issue 4/2017

Discussion
This study evaluated and compared 2 implants
with the same body and prosthetic connection,
but with different neck designs after 3 years of
follow-up to assess the inﬂuence of these variables on periimplant tissue health and radiographic bone loss. The present study did not ﬁnd
statistical differences between the 2 implants on
evaluating PPD, BoP, presence of mucositis, width
of keratinized mucosa and marginal bone loss.
It has been suggested that the initial marginal bone level change occurs as an adaptation
of the periimplant bone to the occlusal load. 23–26
In studies involving a follow-up of over year,1, 23–26
the greatest bone loss was observed during the
ﬁrst year and then bone loss gradually decreased.
The addition of threads or microthreads up to
the crestal module of an implant might provide
a potentially positive contribution to bone–
implant contact, as well as improve preservation
of marginal bone.4, 20, 23, 27 Shin et al. observed
that the most effective design for minimizing
marginal bone loss during functional loading
was a rough surface with microthreads at the
implant neck.12 Abrahamsson and Berglundh
drew a similar conclusion in an experimental
study in dogs.28 They found that the degree of
bone–implant contact within the marginal portion of the implants was signiﬁcantly higher for
the microthreaded implants compared with the
implants with polished necks. Lee et al., in a
well-controlled split-mouth study, also found
that implants with microthreads showed signiﬁcantly less bone loss compared with implants
without them.2 However, although the studied
implants were of the same brand and surface
characteristics, they differed in their macrodesign: one had a tapered neck and the other had
a cylindrical design. In the present study, both
implant models, although distinct in thread conﬁguration, had a tapered design. Bratu et al.
compared implants of the same brand and with
the same dimensions, taper, titanium alloy and
surface characteristics but different neck
designs: one model with a polished neck and the
other with a rough surface and microthreads up
to its prosthetic platform.5 Unlike the present
study, the implants with a rough surface and
microthreads displayed statistically signiﬁcantly
less early marginal bone loss and greater bone
level stability compared with the polished-neck
implants. The results of Piao et al. demonstrated
that the amount of marginal bone loss at 12
months of functional loading was signiﬁcantly

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[21] =>

Periimplant soft-tissue and bone levels with different implant neck designs

Table 1

TSA

TSA Advance

P value (chi2)

3.6
4.2
5.5

2
14
12

1
15
7

0.547

Incisor
Canine
Premolar
Molar

0
1
11
16

1
0
7
15

0.519

Arch

Maxilla
Mandible

0
8

9
14

0.802

Antagonist

Natural tooth
Implant

8
10

18
5

0.276

TSA

TSA Advance

Odds ratio

P value

Probing pocket depth

4.8 ± 1.4 mm

5.3 ± 0.9 mm

Bleeding on probing

47.1%

60%

1.27

0.524

Presence of mucositis

12.5%

14.3%

1.14

0.916

Width of keratinized
mucosa

3.50 ± 2.44 mm

2.70 ± 2.40 mm

Total

TSA

TSA Advance

n

51

28

23

Mean

0.52

0.57

0.46

Standard deviation

0.52

0.55

0.49

Minimum

-0.22

0.00

-0.22

Maximum

2.10

2.10

1.61

Median

0.39

0.47

0.25

Implant diameter (mm)

Implant position

Table 2

Table 2
Statistical results regarding
periimplant clinical variables.
Table 3
Radiographic marginal bone
loss.

0.195

0.435

Table 3

different among the 3 groups they analyzed: The
rough-surfaced microthread implant group
showed less bone loss than the rough-surfaced
implant group and the machined hybrid design
implant group, but these implants had some
differences other than the conﬁguration of the
coronal part, so these might have impacted on
the results.20
Some studies have compared polished-neck
implants to rough-neck implants and found significantly greater bone loss with the polished-neck implants.4, 12, 13, 25, 29–32 In contrast,
others have found no statistically signiﬁcant
differences in bone loss.20, 24, 25, 33, 34 Some studies have evaluated the presence of microthreads
at the coronal portion using radiographic evaluation of the marginal bone level and found a
positive effect in maintaining the marginal bone
level for rough-surfaced implants with

microthreads at the coronal portion after functional loading.1, 13, 20, 35–36 However, Van de Velde
et al. observed that, after 1 year of loading, a
microthread design of the implant collar did not
seem to improve bone preservation in the mandible.38 Aloy-Prósper et al. in their literature
review found that marginal bone loss with polished-neck implants was greater 3 months after
implant placement, while bone loss with roughneck implants with and without microthreads
was greater 6 months after insertion of the
implants.39 Lang et al. in a consensus report
concluded that prospective controlled studies
on the effects of different implant designs and
surfaces demonstrated that marginal bone
levels were generally well preserved after installation of the dental prosthesis (at least for ﬁxed
restorations) on a variety of implant types
(cumulative bone loss: < 0.5 mm after 3 years).11

Journal of
Oral Science & Rehabilitation

Table 1
Descriptive statistics of the
implant sample.

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Periimplant soft-tissue and bone levels with different implant neck designs

Most of the studies measured bone loss from
the start of prosthetic loading to the end of
follow-up, except Nickenig et al., who measured
loss from the time of placement of the implants.14
They compared smooth and rough implants for
restoring missing mandibular molars. In their
study, for smooth implants, bone loss progressed from 0.5 mm in the healing period to
1.1, 1.3 and 1.4 mm in the second, third and ﬁfth
year of follow-up, respectively. In contrast, for
the rough-surfaced, microthreaded implants,
bone loss progressed from 0.1 mm in the healing
period to 0.5, 0.6 and 0.7 mm in the second, third
and ﬁfth year of follow-up, respectively. They
found a significant difference in bone level
changes, suggesting that rough-surfaced,
microthreaded implants more effectively minimized overall marginal bone loss than machinedneck implants did, particularly during the healing period.
Even if some studies have shown less marginal bone loss around implants with a rough
neck, these implants favor bacterial plaque
retention when exposed to the oral environment,
and this in turn would imply an increased risk of
periimplant disease such as mucositis or periimplantits.40, 41 The relatively smooth implant neck
allows the least accumulation of plaque18, 19 and

is designed as a transmucosal component, thus
making the microgap or interface between
implant and restoration easily accessible for oral
hygiene.21
Taking into account the results, it is necessary to highlight the limitations of the present
study. Sample size and the lack of randomization
could limit generalization of the results. Further
studies with a larger sample are needed to clarify the influence of implant neck design on
periimplant tissue health and periimplant bone
remodeling after medium- to long-term functional loading.

Conclusion
According to the results of the present study,
the implant neck designs and neck surface treatments did not signiﬁcantly inﬂuence periimplant
tissue health and radiographic bone loss after
3 years of follow-up.

Competing interests
The authors declare that they have no competing interests.

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[24] =>

Mouthwashes and bacteria on suture threads

Antimicrobial efficacy of mouthwashes
containing zinc-substituted nanohydroxyapatite and zinc L-pyrrolidone carboxylate
on suture threads after surgical procedures
Abstract
Objective
Saverio Cosola,a, b Simone Marconcini,a, b
Enrica Giammarinaro,a, c Olivia Marchisio,a Marco Lelli,d
Norberto Roverid & Anna Maria Genovesia, e
a

Tuscan Stomatologic Institute, Foundation for Dental
Clinic, Research and Continuing Education, Versilia
General Hospital, Lido di Camaiore, Italy
b
Department of Surgical, Medical, Molecular and Critical
Area Pathology, University Hospital of Pisa, University
of Pisa, Pisa, Italy
c
Department of Stomatology, Faculty of Medicine
and Dentistry, University of Valencia, Valencia, Spain
d
“Giacomo Ciamician” Department of Chemistry,
University of Bologna, Bologna, Italy
e
Department of General Hygiene, Guglielmo Marconi
University, Rome, Italy

Corresponding author:
Dr. Saverio Cosola
Tuscan Stomatologic Institute
Via Padre Ignazio da Carrara, 39
55045 Forte dei Marmi LU
Italy

Suture threads used after oral surgery may be colonized by pathogenic
microorganisms which could infect the surrounding tissue and impair
the wound-healing process. Therefore, the postoperative use of antimicrobial mouthwashes is highly recommended. In this study, a mouthwash containing zinc-substituted nanohydroxyapatite (Zn-nHAp) and
zinc L-pyrrolidone carboxylate (Zn-PCA) was compared with a product
containing chlorhexidine for its efficacy in reducing microbial adherence
to suture threads.
Materials and methods

Twenty-six patients subjected to minimal surgical interventions were
randomized into a chlorhexidine group (C-group; n = 13) and a hydroxyapatite group (H-group; n = 13). All of the subjects followed a postoperative home treatment with a mouthwash containing chlorhexidine and
a mouthwash containing Zn-nHAp/Zn-PCA, respectively. After their
removal, suture threads were cut into segments and bacteria present on
them were allowed to grow in different media and under different conditions. Colony-forming units were then enumerated.

T +39 0584 605 9888
F +39 0584 605 8716
saverio.cosola@gmail.com

Results

How to cite this article:
Cosola S, Marconcini S, Giammarinaro E, Marchisio O,
Lelli M, Roveri N, Genovesi AM. Antimicrobial
efficacy of mouthwashes containing zinc-substituted
nanohydroxyapatite and zinc L-pyrrolidone carboxylate
on suture threads after surgical procedures.
J Oral Science Rehabilitation. 2017 Dec;3(4):24–30.

Quantiﬁcation of mesophilic bacteria, Lactobacillus spp and total bacterial load and the search for speciﬁc anaerobic strains resulted in no
statistically signiﬁcant differences between the C-group and H-group.
Hydroxyapatite, zinc ions and Zn-PCA are all endowed with antimicrobial
properties. All of them presumably contribute to the overall high antimicrobial efficacy shown by oral care products containing a combination
of these components.
Conclusion

The mouthwash containing Zn-nHAp and Zn-PCA was found to possess
at least the same antibacterial efficacy as the mouthwash containing
chlorhexidine, but without exerting the typical side effects of chlorhexidine itself.
Keywords

Zinc-substituted nanohydroxyapatite, zinc L-pyrrolidone carboxylate,
bacterial load, mouthwash, suture thread.
24 Volume 3 | Issue 4/2017

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Oral Science & Rehabilitation

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Mouthwashes and bacteria on suture threads

Introduction
Oral surgery interventions usually require
sutures in order to facilitate wound healing and
to prevent dehiscence. However, suture threads
are inevitably colonized by microorganisms
that could infect surrounding tissue and impair
the wound-healing process.1–4 Many different
kinds of surgical sutures (natural and synthetic)
with different properties have been proposed
over the years to overcome plaque stratiﬁcation over threads. It is already known that bacterial adherence to suture threads may delay
and affect the wound-healing process. For this
purpose, several antimicrobial agents have
been tested to be incorporated in or to coat
suture threads. 5 Mouthwashes are highly recommended for home care maintenance as an
adjunctive measure to reduce bacterial colonization of sutures and postoperative inﬂammation. 6 Nowadays, chlorhexidine is the gold
standard in terms of antimicrobial activity
because of its wide spectrum of actions. Chlorhexidine has been commercially proposed in
many different formulas.7 Even though its several advantages have been profusely demonstrated, some adverse effects, such as tooth
staining, 8, 9 tongue discoloration, and desquamation and soreness of the oral mucosa, should
be considered. 3, 10–12 Because of its nature, clinicians must look at chlorhexidine as an antimicrobial agent to which bacteria could develop
resistance, especially in the case of long-term
use.13 Given those issues, researchers have
been seeking alternatives to chlorhexidine in
terms of antiseptic designs. In the present
study, the authors tested a mouthwash containing zinc-substituted nanohydroxyapatite
(Zn-nHAp) and zinc L-pyrrolidone carboxylate
(Zn-PCA) in terms of microbial adherence to
suture threads compared with a mouthwash
containing chlorhexidine.

Materials and methods
Study protocol

The present clinical case–control study was a
multicenter study including the Tuscan Stomatologic Institute, Versilia General Hospital, Lido di
Camaiore, Italy, and the University of Bologna,
Bologna, Italy. All of the participants were
screened according to the following inclusion
and exclusion criteria.

Inclusion criteria:
– aged 30 years and older;
– received minimal surgical interventions
(extraction, implant surgery, periodontal surgery) with sutures; and
– compliance with the study protocol and willingness to adhere to the hygiene instructions.
Exclusion criteria:
– pregnancy;
– antibiotics, nonsteroidal anti-inﬂammatory
drugs, or steroids in the previous 3 months;
– severe systemic disease that could compromise the conduct of the study;
– untreated diabetes;
– chronic or aggressive periodontitis or other
severe oral pathologies;
– smoking more than 5 cigarettes a day; and
– alcohol or other drug abuse.
At the end of the screening procedure, 26 patients
were enrolled in the study and randomized into
2 maintenance groups according to the mouthwash used: (a) a control group (the chlorhexidine
group, or C-group, n = 13), in which the patients
followed a postoperative home treatment for at
least 7 days with a mouthwash containing 0.2%
chlorhexidine (Dentosan, Johnson & Johnson,
Rome, Italy); and a treatment group (the hydroxyapatite group, or H-group, n = 13), in which the
patients followed a postoperative home treatment for at least 7 days with a mouthwash containing Zn-nHAp/Zn-PCA (Biorepair, Coswell,
Funo, Italy), with a 2.0% w/v concentration of
Zn-nHAp and an overall concentration of Zn of
11.0% w/v. Nonabsorbable silk sutures (Sweden
& Martina, Due Carrare, Italy) were removed after
10 days from the surgical sites of all of the
patients. All sutures were placed and removed
by the same skilled operator to eliminate interexaminer variability. The collected samples were
immediately transported to the laboratory and
stored at -20 °C until microbiological analysis.
All subject randomization was performed by
means of a computer program generating
random numbers. Oral and written information
was given to each enrolled subject. All of the
patients enrolled were informed about the study
protocol and were asked to sign an informed
written consent for participation. This study was
carried out according to the ethical principles of
the Declaration of Helsinki of 1975, as revised in
2013, for medical research involving human subjects. Figure 1 provides a ﬂowchart summarizing
the study protocol.

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Mouthwashes and bacteria on suture threads

Fig. 1

Fig. 1
Flowchart illustrating the
study protocol.

Culture media and conditions

Bacteria were cultured in Petri dishes containing
tryptone soy agar (TSA) as growth medium at
an incubation temperature of 36 ± 1 °C. In this
way, it was possible to obtain the growth of
mesophilic bacteria. De Man, Rogosa and Sharpe
(MRS) agar at 36 ± 1 °C allowed the growth of
Lactobacillus spp. Bacteroides bile esculin (BBE)
agar and brucella blood agar (BRU) with vitamin
K and hemin, incubated at 36 ± 1 °C under anaerobic conditions allowed the qualitative analysis
of speciﬁc anaerobic strains.

samples were thawed at room temperature.
Each sample was cut into 3 segments of similar
length, then each thread sample was subjected
to analysis as follows. The control sample was
represented by segments of a sterile, unused
suture thread.

bacterial scoring

Assessment of the absence/presence of bacterial load: Two segments of the thread were
scraped on 2 culture plates containing agarbased broth media (TSA and MRS) and incubated
for 48 h at 36 ± 1 °C in order to determine
whether microbial load was present on the
thread surface. The plates were visually
inspected and bacterial load accordingly classiﬁed as absent or present.

Microbial load was assessed after suture
removal using in vitro bacterial cultures.
Suture thread samples were stored at -20 °C
until microbiological analysis. Before testing,

Enumeration of bacterial colonies: One segment
was placed in a tube containing a diluent solution
(buffered peptone water; BPW) for 1 h, then, further serial decimal dilutions were carried out.

Te s t p r o c e d u r e a n d

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Mouthwashes and bacteria on suture threads

Each dilution, the ﬁrst included, was seeded in
plates with the same agar-based broth media
and incubated for 48 h at 36 ± 1 °C in order to
quantify the microbial load. Bacterial colonies
were then counted and expressed as colonyforming units per mL (cfu/mL). Concerning the
enumeration of bacterial colonies, a bacterial
score (BS) was obtained by classifying the
enumerated bacterial colonies according to the
following scheme:
– Class 0: BS ≤ 103 cfu/mL
– Class 1: ≤ 103 cfu/mL BS ≤ 105 cfu/mL
– Class 2: ≤ 105 cfu/mL BS ≤1 07 cfu/mL
– Class 3: BS > 107 cfu/mL
Search for specific anaerobic bacteria: Each
sample was seeded on 2 different plates (BBE and
brucella blood agar) to determine the eventual
presence of anaerobic microbial strains. Seeded
plates were placed in the oxygen-free vessels and
incubated at 36 ± 1 °C for 7 days. After this period,
the plates were analyzed to evaluate the presence
of bacterial colonies. In positive cases, individual
colonies were reseeded to achieve a pure bacterial culture suitable for biochemical recognition.
For evaluation of the growth of speciﬁc anaerobic
bacteria, the classes of “growth” and “no growth”
were established, depending on whether bacterial growth was observed.

mean ± SD score of bacteria-seeding calculated
on MRS was 1.462 ± 1.050 and 1.077 ± 1.320 in
the H-group and C-group, respectively. In all
cases, the P values were not statistically significant, meaning that no statistically signiﬁcant
differences were observed between the H-group
and the C-group. In more detail, the total bacterial load developed after seeding BPW solutions that had been in contact with suture thread
segments on TSA plates and the Lactobacillus
spp. developed after seeding BPW solutions that
had been in contact with suture thread segments were comparable between groups.
Table 2 is the contingency table summarizing
data resulting from inoculation on BRU plates.
In this case too, no statistically signiﬁcant differences between the H-group and C-group
were observed (P = 0.411). Tables 3 and 4 are
contingency tables summarizing data resulting
from scraping suture thread segments on TSA
plates and MRS plates, respectively. Again, no
statistically signiﬁcant differences between the
H-group and C-group were observed. Inoculation in BBE under anaerobic conditions produced
negative results (no growth) for all samples and
the control. Figure 2 illustrates Petri dishes after
the optional development of bacterial colonies.

Discussion
Statistical analysis

Data were expressed as mean ± standard deviation (SD) of BS values, where available. The
Mann–Whitney U test for independent samples
was used to evaluate the difference between the
C-group and H-group. In the case of categorical
data, that is growth/no growth classes and
absence/presence classes, data were organized
in contingency tables and analyzed by the Fisher
exact test. A value of P ≤ 0.05 was taken as
statistically signiﬁcant. Statistical analysis was
performed using OpenStat version 26.03.2012
(www.statprograms4u.com).

Results
The results of the microbiological analysis are
summarized in Tables 1 – 4. Table 1 reports
mean ± SD values for BSs calculated from the
cfus developed under different conditions. The
mean ± SD score of bacteria seeding calculated
on TSA was 2.000 ± 1.080 and 1.462 ± 1.198 in
the H-group and C-group, respectively. The

The present study aimed to evaluate the bacterial load on suture threads after their removal in
2 different situations. Patients were assigned
either to a chlorhexidine mouthwash or to a zinc
one. Among the suture thread samples taken
from the 13 patients who used the mouthwash
containing chlorhexidine (C-group), 7 showed a
high bacterial load (BS = 2 or 3) with the presence of Lactobacillus spp, in 5 cases; 2 of them
presented a poor bacterial load (BS = 1); and 4
of them did not present any appreciable microbial colonization (BS = 0). The search for speciﬁc
anaerobic strains, when positive (3 samples),
resulted in establishing the presence of Fusobacterium varium (1 occurrence), Actinomyces
meyeri (1 occurrence) and Streptococcus intermedius (1 occurrence). Of the 13 suture thread
samples taken from patients who used a mouthwash containing Zn-nHAp/Zn-PCA, 10 showed
a high bacterial load (BS = 2 or 3) associated with
the presence of Lactobacillus spp., 1 had a moderate bacterial load (BS = 1), and 2 did not show
any appreciable microbial colonization. The
search for speciﬁc anaerobic strains, when pos-

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Mouthwashes and bacteria on suture threads

Table 1

Table 1
Mean ± SD values for BSs
calculated from the cfus
developed under different
conditions. From left to right,
the columns report data
concerning the quantiﬁcation
of total bacterial load and
Lactobacillus spp.,
respectively, after seeding the
BPW solutions that had been
in contact with suture thread
segments. Growth media were
TSA and MRS agar,
respectively.

Hydroxyapatite
Chlorhexidine

Inoculation
on BRU

Table 2
Contingency table
summarizing data resulting
from inoculation on BRU.

Scraping on TSA
Table 3
Contingency table
summarizing data resulting
from scraping on TSA.
Table 4
Contingency table
summarizing data resulting
from scraping on MRS.

†

Seeding on MRS

2.000 ± 1.080

1.462 ± 1.050

1.462 ± 1.198

1.077 ± 1.320

P = 0.2668

P = 0.4084
Table 2

Hydroxyapatite
n

Chlorhexidine
n

P

6
7

3
10

0.411

Hydroxyapatite
n†

Chlorhexidine
n

P

2
10

3
10

1.000

Growth
No growth

Absence
Presence

Table 3

The total number of suture threads in the H-group was 12 instead of 13 because 1 thread was too short to be cut into segments for scraping on TSA plates.

Scraping on MRS
†

Seeding on TSA

Table 4

Hydroxyapatite
n†

Chlorhexidine
n

P

3
9

7
6

0.226

Absence
Presence

The total number of suture threads in the H-group was 12 instead of 13 because 1 thread was too short to be cut into segments for scraping on MRS plates.

itive (6 samples), resulted in establishing the
presence of Actinomyces meyeri (3 occurrences),
Biﬁdobacterium spp. (1 occurrence), Staphylococcus saccharolyticus ( 1 occurrence) and
Actinomyces viscosus (1 occurrence).
In vitro studies have already demonstrated
that hydroxyapatite shows antimicrobial activity; for example, Tin-Oo et al. reported the efficacy of HAp against Streptococcus mutans.19 The
antimicrobial activity of nHAp was also investigated when intercalated by several metal ions,
including zinc ions,15, 16 and shown to be higher
than that of nHAp alone. Furthermore, zinc ions
are known to possess antimicrobial properties,
and the activity of zinc in the oral cavity has been
well documented.17, 18 PCA possesses a certain
antimicrobial activity as well, as demonstrated
by Yang et al., who tested it in in vivo studies
against several microorganisms.19 Moreover,
PCA increases the solubility rate of zinc ions in
the saliva such that its antibacterial action is
readily exerted.
Oral care products based on the association
of Zn-nHAp and Zn-PCA could create a combination of 3 active ingredients that are very well
tolerated and maintain the same efficacy of
chlorhexidine against bacteria. Indeed, the present study demonstrated that mouthwashes
28 Volume 3 | Issue 4/2017

containing Zn-nHAp and Zn-PCA represent a
valid alternative to mouthwashes containing
chlorhexidine. They do not exert the typical side
effects of chlorhexidine, such as alteration of
taste perception, tooth staining, tongue discoloration, and desquamation and soreness of the
oral mucosa, while maintaining at least its same
antibacterial efficacy.20 Also, Marchetti et al., in
a clinical comparative trial, found a similar effect
of inhibiting plaque regrowth between zinc and
chlorhexidine mouthwashes.21 Further studies
are needed to better understand whether this
new antimicrobial mouthwash could substitute
chlorhexidine as the gold standard in promoting
wound healing after surgery owing to its antimicrobial effect and no side effects.

Conclusion
Within the limitations of this study, the mouthwash containing Zn-nHAp and Zn-PCA was
found to have similar antibacterial efficacy to the
mouthwash containing chlorhexidine, but without exerting the typical side effects of chlorhexidine itself. These results should be interpreted
with caution owing to the small sample of the
study and the few kinds of bacteria analyzed.

Journal of
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[29] =>

Mouthwashes and bacteria on suture threads

Figs. 2A–F

Figs. 2A–F
Petri dishes after the optional
development of bacterial
colonies. A and B come from
patients who used a
mouthwash containing
chlorhexidine for 7 days after
surgery. C, D and E come from
patients who used a
mouthwash containing
Zn-nHAp and Zn-PCA for
7 days after surgery.
F represents control plates.
Within each photograph,
the upper left and right plates
correspond to suture thread
segments scraped on TSA for
the growth of mesophilic
bacteria and MRS agar for the
growth of Lactobacillus spp.,
respectively. The bottom left
and right plates correspond
to the quantitative analysis of
mesophilic bacteria on TSA
and Lactobacillus spp. on MRS
agar, respectively.

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[30] =>

Mouthwashes and bacteria on suture threads

Competing interests
The authors declare that they have no conﬂict
of interest regarding the present research.

Acknowledgments
The authors are grateful to the Chemical Center,
Bologna, Italy, for technical support and to Drs.
Alice Borghini and Daniele Pietra for statistical
analysis and manuscript drafting.

– Prof. Ugo Covani, Department of Surgical, Medical, Molecular and Critical Area Pathology,
University of Pisa, Pisa, Italy; and Tuscan
Stomatologic Institute, Foundation for Dental
Clinic, Research and Continuing Education,
Versilia General Hospital, Lido di Camaiore, Italy;
– Dr. Andrea Butera, Department of Surgical
Sciences, Dental and Maxillofacial Department, University of Pavia, Pavia, Italy; and
– Drs. Dario Bertossi, Antonio Iurlaro and Federico Gelpi, Department of Surgical Sciences
and Dental and Maxillofacial Department,
University of Verona, Verona, Italy.

For their important contribution to this investigation, the authors are also very grateful to

References
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Otten JE, Wiedmann-Al-Ahmad M,
Jahnke H, Pelz K. Bacterial colonization
on different suture materials—a potential
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can an antimicrobial rinse help?
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2.
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M, Gallesio C, Allizond V, Angeretti A,
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H, Ogier J, Haikel Y, Vodouhe C.
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Frank ME, Gent JF, Hettinger TP. Effects
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12.
Marinone MG, Savoldi E. Chlorhexidine
and taste. Inﬂuence of mouthwashes
concentration and of rinsing time.
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2000 May;49(5):221–6.

14.
Tin-Oo MM, Gopalakrishnan V,
Samsuddin AR, Al Salihi KA,
Shamsuria O. Antibacterial property
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→ Arch Orofac Sci.
2007;2:41–4.
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Swetha M, Sahithi K, Moorthi A, Saranya
N, Saravanan S, Ramasamy K, Srinivasan
N, Selvamurugan N. Synthesis,
characterization, and antimicrobial
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2012 Jan;12(1):167–72.
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Kim TN, Feng QL, Kim JO, Wu J, Wang H,
Chen GC, Cui FZ. Antimicrobial effects of
metal ions (Ag+, Cu2+, Zn2+) in
hydroxyapatite.
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Hannig C, Basche S, Burghardt T,
Al-Ahmad A, Hannig M. Inﬂuence of
a mouthwash containing hydroxyapatite
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2013 Apr;17(3):805–14.
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Yang Z, Suomalainen T, Mäyrä-Mäkinen
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Flötra L, Gjermo P, Rölla G, Waerhaug J.
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Marchetti E, Casalena F, Capestro A,
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[31] =>

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[32] =>

1-year study of nonsubmerged implants

Multifactorial statistical analysis toward
evaluation of MBL, PES and PI of a novel nonsubmerged implant to restore a single tooth:
A 1-year prospective cohort study
Abstract
Objective
Carlo Prati,a Fausto Zamparini,a, b Chiara Pirani,a
Lucio Montebugnolia & Maria Giovanna Gandolﬁb
a

Endodontic Clinical Section, Department of Biomedical
and Neuromotor Sciences, School of Dentistry, University
of Bologna, Bologna, Italy
b
Laboratory of Biomaterials and Oral Pathology, Department of Biomedical and Neuromotor Sciences, School of
Dentistry, University of Bologna, Bologna, Italy

Corresponding author:
Prof. Carlo Prati
Via San Vitale, 59
40125 Bologna
Italy
T +39 051 208 8126
carlo.prati@unibo.it
How to cite this article:
Prati C, Zamparini F, Pirani C, Montebugnoli L, Gandolﬁ
MG. Multifactorial statistical analysis toward evaluation
of MBL, PES and PI of a novel nonsubmerged implant to
restore a single tooth: A 1-year prospective cohort study.
J Oral Science Rehabilitation. 2017 Dec;3(4):32–41.

The objective of this study was to evaluate radiographic, clinical and
esthetic parameters of a new type of nonsubmerged 2-piece implant
placed in patients in need of single-tooth replacement.
Materials and methods

Fifty-four consecutive patients requiring single-tooth replacement
received 62 2-piece nonsubmerged ﬂapless implants characterized by
an innovative hyperbolic neck. The implant placement timing was as
follows: 15 immediately post-extraction (immediate), 18 after 8–12
weeks (early) and 29 after 10–12 months (delayed). Customized abutments with an abutment–implant connection approximately 1–2 mm
above the soft-tissue level were positioned after 3 months, loaded with
provisional crowns and 20 days later with deﬁnitive crowns.
Gingival biotype (thin or thick) was investigated in all patients. Periimplant marginal bone level (MBL; mm) was measured single-blinded on
periapical radiographs at 1, 3, 6 and 12 months (T1, T3, T6, T12). Papilla index
(PI), plaque score and bleeding on probing (BoP) were evaluated as clinical
parameters of soft tissue. Pink Esthetic Score (PES) was calculated as
the esthetic parameter.
Results

The survival rate was 100%. The dropout rate was 1.85%. The mean MBL
was - 0.01 ± 0.26 at T1 , - 0.17 ± 0.38 at T3 , - 0.28 ± 0.32 at T6 and
- 0.37 ± 0.41 at T12. The PES (0–14) was 7.30 ± 2.80 at T0 (preoperatively),
11.06 ± 0.97 at T6 and 11.95 ± 1.04 at T12.
At (T12), delayed implants showed a greater (P < 0.05) bone loss compared
with early and immediate implants. Implants placed in thin biotype tissue
showed the greatest bone loss at 12 months with a signiﬁcant (P < 0.01)
difference with respect to that at (T6). PES and PI increased from T0 to T12.
Conclusion

These implants allow preservation of a good MBL and offer a new
approach to soft- and hard-tissue management, allowing a reduced
healing time with minimally invasive surgery, no additional re-entry and
fewer complications.
Keywords

Nonsubmerged dental implants, ﬂapless surgery, marginal bone level (MBL),
papilla index (PI), bleeding on probing (BoP), Pink Esthetic Score (PES).
32 Volume 3 | Issue 4/2017

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1-year study of nonsubmerged implants

Introduction
Flap raising and surgical trauma,1, 2 second
re-entry surgeries and application of subgingival
abutments3 may lead to both hard- and softtissue complications, i.e., crestal bone loss, wound
dehiscence and gingival recession. The need for
less-invasive protocols may be useful to avoid
these complications. The use of nonsubmerged
implants may prevent any surgical re-intervention
for cover screw exposure and abutment or further
prosthetic phases. The use of a ﬂapless technique
may reduce the risk of surgical complications and
marginal bone loss.4, 5 The type of implant and
morphology of the neck may play some critical
role in preserving marginal soft and bone tissue.
Recently, a new 2-piece nonsubmerged zirconium dioxide-blasted, acid-etched titanium
implant (Prama, Sweden & Martina, Due Carrare,
Italy) was marketed based on the biologically
oriented preparation technique (BOPT). This prosthetic approach entails the creation of an ideal
esthetic contour through gingival adaptation of
the crown without the need for invasive surgical
procedures. The crown is positioned on a previously prepared tooth with no ﬁnishing line, allowing the possibility of creating a new prosthetic
cementoenamel junction and allowing the crown’s
gingival margin to be shaped as desired.6 This
prosthetic technique was ﬁrst described in the
context of natural tooth-supported restorations,7
but may be applied also to implant rehabilitation.
The Prama implant was designed with a 3 mm
hyperbolic machined neck that simulates a natural prosthetic abutment without a ﬁnishing line.
Short-term case reports and case series are
beginning to be published in the literature. 8, 9
Preliminary investigations have found promising
soft- and hard-tissue management using a ﬂapless technique and indicated that all prosthetic
procedures resulted in simpler and easier procedures than with a conventional submerged
implant–abutment connection.8–10
The aim of this consecutive prospective
cohort study was to evaluate the failure rate and
hard- and soft-tissue modiﬁcations and parameters during the ﬁrst year of placement of nonsubmerged Prama implants.

clinical and radiographic parameters after 1 year
for the treatment of patients who required
replacement of a single tooth. The study was
conducted in a university endodontic clinical
department and 2 private dental offices. Patient
recruitment was performed from September
2014 to September 2015. Patients were followed
up between October 2014 and May 2017 by the
same clinical team.
All of the patients included in this investigation
were treated according to the principles established by the Declaration of Helsinki of 1975, as
revised in 2013.11 Before enrolment, written and
verbal information were given by the clinical staff
and each patient gave written consent according
to the above-mentioned principles. An additional
signed informed consent was obtained from all
patients stating that they accepted the treatment
plan and agreed to cover the costs and follow the
maintenance hygiene program. This report was
written according to the Strengthening the
Reporting of Observational Studies in Epidemiology (STROBE) 12 and respecting the guidelines
published by Dodson in 2007.13 The patients were
considered eligible for inclusion in the clinical protocol based on the following inclusion criteria:
– aged 18–75;
– presence of a single failing tooth or a single
tooth gap with both neighboring teeth present;
– possibility of inclusion in a hygiene recall program and implant control for at least 1 year; and
– smoking less than 10 cigarettes a day.

Materials and methods

Exclusion criteria were as follows:
– medical and/or general contraindications for
the surgical procedures (American Society of
Anesthesiologists Physical Status ≥ 3);
– poor oral hygiene and lack of motivation;
– active clinical periodontal disease in the natural dentition determined by a probing pocket
depth > 4 mm and bleeding on probing;
– smoking more than 10 cigarettes a day;
– uncontrolled diabetes mellitus;
– systemic or local disease that could compromise
postoperative healing and osseointegration;
– alcohol and/or drug abuse;
– pregnancy or lactation;
– malocclusion or other occlusal disorder
(bruxism); and
– bisphosphonate therapy.

Study setting and patient selection

Patient allocation

The study design was a single-blinded human The timing of implant placement (immediate,
longitudinal prospective cohort study evaluating early or delayed according to the third ITI
Journal of
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Volume 3 | Issue 4/2017 33

[34] =>

1-year study of nonsubmerged implants

Consensus Conference)14 was speciﬁcally determined by an experienced university clinician
following rigorous criteria aimed at best clinical
practice (judgmental allocation).15
The following groups were deﬁned:
– Immediate post-extraction implant group (type 1
for ITI):14 placement of the implant into the fresh
extraction socket immediately after extraction
of a tooth affected by chronic periapical disease
or of a seriously damaged, hopeless tooth. Only
chronic periapical lesions were present and
identiﬁed by periapical radiolucency.
– Early implant group (type 2 for ITI):14 placement of the implant in healed bone after 8–12
weeks after extraction of a tooth affected by
an acute periapical lesion and/or abscess, pus
and clinical symptoms.
– Delayed implant group (type 4 for ITI):14 placement of the implant in edentulous mature
bone 10–12 months after tooth extraction.
Preoperative protocol

The day before surgery, all of the patients were
subjected to a preventive pharmacological treatment consisting of 1 g of amoxicillin/clavulanic
acid (Augmentin, GlaxoSmithKline, Brentford,
U.K.; 1 tablet at 24 and 12 h before the surgery)
and a 0.12 % chlorhexidine digluconate gel
(Corsodyl Gel, GlaxoSmithKline; 3 applications
per day). Antibiotic administration was continued for 5 days postoperatively.
Implant surgery

Implant surgeries were conducted by the same
operator (C.P.) under local anesthesia with
30 mg/mL of mepivacaine hydrochloride
(Carboplyina, Dentsply Italia, Rome, Italy) in sterile
conditions. All of the implants were placed in
1-stage surgical procedures. No ﬂaps were raised
and no surgical guides were used.
A pilot drill of 1.2 mm in diameter was used to
mark the position, angle and depth. The drill
passed through the mucosa (nonsubmerged), cortical bone and cancellous bone at 225 rpm. A series
of calibrated drills working at 225 rpm were used
to create a site of adequate depth and diameter.
Prama implants, characterized by a 3 mm
transmucosal machined neck with a hyperbolic
proﬁle (as illustrated by the environmental scanning electron microscopy image in Fig. 1) were
inserted to keep the blasted surface at cortical
bone level and the smooth machined neck
34 Volume 3 | Issue 4/2017

surface 1–3 mm above the gingival level, according to the transmucosal technique.16 No sutures
were placed. A surgical dressing (COE-PAK, GC
America, Alsip, Ill., U.S.) was applied to the
implant site and kept in position for 5–7 days.
Postoperative procedures

Patients were instructed to follow a soft diet
regime for 1 week, to rinse 3 times per day with
a 0.12% chlorhexidine mouthwash for 3 weeks
and to perform oral hygiene on the COE-PAK
using a normal-medium-hardness toothbrush
for the ﬁrst week and for 2 weeks after removal
of the surgical dressing. Thereafter, conventional brushing and ﬂossing were permitted.
Prosthetic restoration

Three months after implant insertion, impressions
using polyether materials (Permadyne and Garant,
3M ESPE, St. Paul, Minn., U.S.) were taken using
customized resin trays (pickup impression technique). Gypsum model casts were obtained and
provisional resin crowns were carefully designed
to keep the crown margins at gingival level with
the ﬁnishing line on the implant hyperbolic neck.
Customized titanium abutments were
screwed in after 5–7 days. All of the resin crowns
were positioned with temporary cement (Temp
Bond, Kerr, Scafati, Italy) for initial prosthetic
restoration. In this way, the implant–abutment
connection was internal to the crowns. Abutments were intended to increase the retention
of the cement–crown monobloc.
Twenty days later, definitive prosthetic
metal–ceramic crowns were positioned and ﬁxed
with a polycarboxylate cement (Heraeus Kulzer,
Hanau, Germany). Deﬁnitive crowns were also
prepared according to the BOPT so that all metal
and ceramic ﬁnishing lines corresponded to the
implant hyperbolic neck. Fitting of the metal was
gently and carefully done to create a mechanical
metal–metal friction. Two experienced prosthodontists (C.P. and L.M.) performed all of the prosthetic procedures. Great attention was given to
avoiding any cement excess around the restorations.
Follow-up implant evaluation

Active periodontal therapy consisting of motivation, instruction in oral hygiene practice,
scaling and root planing was performed until no
or modest periodontal disease was present.

Journal of
Oral Science & Rehabilitation

[35] =>

1-year study of nonsubmerged implants

Fig. 1

Fig. 1
Optical microscopy and
environmental scanning
electron microscopy images
showing the hyperbolic
machined collar and the
microtopography of the collar,
body and apex portions of
Prama implant.

Hard- and soft-tissue evaluation

Marginal bone level (MBL): Intraoral periapical
radiographs of all of the implants were taken
using the paralleling technique with Rinn holders (Dentsply Rinn, Elgin, Ill., U.S.) and analog
ﬁlms (Kodak Ektaspeed Plus, Eastman Kodak,
Rochester, N.Y., U.S.) after implant placement
(baseline) and at 1, 3, 6 and 12 months (T1 , T3 , T6 ,
T12) after implant insertion.
All radiographs were scanned with a slide
scanner with a resolution of 968 dpi and a magniﬁcation factor of ×20. The known lengths and
diameters of the implants were used to calibrate
the measurement. The crestal marginal bone
and the bone–implant interface were examined
to evaluate the marginal bone morphology. MBL
was assessed at the mesial and distal implant
surfaces by measuring the distance between
the reference point of the implant platform to
the most coronal bone–implant contact level
using a scale of 0.1 mm increments according to
previous studies17, 18 and corrected according to
the known length and diameter of each implant.19
Radiographic evaluation was performed
single-blinded by 1 additional examiner (F.Z.).
Before evaluating the radiographs, the examiner
was calibrated using well-deﬁned instructions
and reference radiographs with different MBL
measures.
Periimplant soft-tissue thickness/gingival
biotype: The soft-tissue thickness around the
implants and their corresponding mesial/distal
neighboring teeth was determined. The soft
tissue was pierced midfacially at 3 mm apical to
the gingival margin with an endodontic file
(No. 20 K-ﬁle, Dentsply Maillefer, Switzerland).
Gingival biotype was defined as thick (softtissue thickness > 2 mm) or thin (soft-tissue
thickness ≤ 2 mm).20–22
Pink Esthetic Score (PES): PES 23 was
assessed preoperatively and at T6 and T12. Seven

variables were evaluated against a natural reference tooth by 1 trained operator (the contralateral tooth for an incisor and contralateral
tooth or neighboring tooth for a premolar) using
a 0–2 scoring system (0 being the lowest and 2
being the highest value): mesial papilla, distal
papilla, soft-tissue level, soft-tissue contour,
alveolar process deﬁciency, soft-tissue color and
soft-tissue texture. The maximum achievable
PES was 14. According to Raes et al., a PES < 8
is considered an esthetic failure, while a PES
≥ 12 is considered an (almost) perfect outcome.1
Papilla index (PI): PI24 was assessed mesially
and distally by 1 trained operator using a 0–4
scale at T6 and T12. A PI score was given as follows: 0 = no papilla; 1 = papilla ﬁlls less than 50%
of the interproximal space; 2 = papilla ﬁlls more
than 50% of the interproximal space, but not
entirely; 3 = papilla ﬁlls the entire interproximal
space harmoniously; 4 = hyperplastic papilla.
Plaque score: Plaque score25 was assessed
at 4 sites (mesial, distal, vestibular and palatal)
around the implant restorations at T6 and T12. A
dichotomous score was given (0 = no visible
plaque at the soft margin; 1 = visible plaque at
the soft margin).
Bleeding on probing (BoP): BoP25 was measured at 4 sites (mesial, distal, vestibular and
palatal) around the implant restorations at T6
and T12. A dichotomous score was given (0 = no
bleeding; 1 = bleeding).
Statistical analysis of the MBL

Linear regression models were ﬁtted to evaluate
the existence of any significant difference
regarding placement (immediate, early and
delayed), times (1 month, 3 months, 6 months
and 12 months), and the interactions between
placement and time. In order to take into account
the correlation in the data due to the presence
of multiple implants per subject, the

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above-mentioned regression models were estimated following a generalized estimating equation approach. The implant was used as the unit
of analysis. We adjusted the estimates of the
coefficients’ standard errors and confidence
intervals using a robust variance–covariance
estimator.26 The same analysis was performed
for gingival biotype.
A multiple linear regression model with stepwise selection was ﬁtted to evaluate the relationship between MBL at 12 months and the
following variables: sex (male/female), location
(mandible/maxilla), tooth type (anterior/posterior),
endodontically treated adjacent teeth (yes/no),
implant placement (immediate, early, delayed),
implant diameter (3 . 80, 4 . 25 or 5 .00 mm),
implant length (10.0/11.5 mm) and gingival biotype (thin/thick). All statistical analysis was
performed using Stata (Version 13.1, StataCorp,
College Station, Texas, U.S.).

Results
Based on the inclusion and exclusion criteria,
54 patients (62 implants) with a mean age of
56.8 ± 12.0 years (26 men and 28 women) were
included. Table 1 depicts implant distribution
and MBL (mean ± SD) at 12 months according to
the pre-, intra- and postoperative parameters
evaluated.
The survival rate was 100%. The total patient
dropout rate was 1.85%. No wound infection,
osteitis, bone graft sequestration or implant
loosening occurred during the follow-up period.
Mean MBL values according to implant
placement group and gingival biotype are
reported in Tables 2 and 3, respectively. The
delayed implant group showed the greatest
bone loss from T6 to T12, the difference being
statistically signiﬁcant (P < 0.05) with respect
to both the early and immediate groups. The
early implant group showed the lowest bone loss
at all times. Interestingly, all 3 groups showed a
statistically different MBL at T3 with respect to
T1 . Considering gingival thickness, MBL signiﬁcantly (P < 0.01) decreased with time in both
groups, but patients with a thin biotype showed
a greater bone loss (P < 0.01) than patients with
a thick biotype. A statistically signiﬁcant difference (P < 0.01) in MBL between groups was
found at 6 and at 12 months. The results of the
multiple linear regression (Table 4a) showed that
implant diameter and gingival biotype were the
only variables signiﬁcantly (P < 0.01) related to
36 Volume 3 | Issue 4/2017

MBL at T12, the gingival biotype being the most
important one (Table 4b).
As soft-tissue evaluation parameters, PES
and PI assessment are reported in Tables 5 and 6.
Adequate/good PES scores were reported for all
implants, increasing from T6 to T12 . Also, PI
increased from T6 to T12. Plaque score and BoP
are reported in Table 7. A clinical photograph
sequence of an example of implant rehabilitation
is shown in Figure 2 . A periapical radiograph
sequence of a representative case is presented
in Figure 3.

Discussion
The study has demonstrated that the proposed
nonsubmerged technique with a hyperbolic neck
design allows the achievement of a stable
periimplant MBL and an adequate soft-tissue
morphology. MBL was evaluated at 1 and 3
months after implant insertion (preloading
period) and demonstrated very limited bone loss
despite the gingival emergence of a yellow
implant neck.
Previous studies have evaluated MBL from
initial loading (postloading period), not considering that bone loss may occur during the preloading time.5 Interestingly, in the present study,
a stable MBL was observed after 1 month from
insertion. The ﬂapless technique27–29 probably
minimized surgical trauma that may be responsible for initial marginal bone loss. 30
Our investigation is the ﬁrst prospective clinical study to evaluate a high number of clinical
(BoP, PI and plaque score), radiographic (MBL)
and esthetic (PES) parameters and include a
reasonable number of implants and patients.
Currently, only a case report8 and a prospective
cohort study10 at 18 months with just 14 patients,
showing a stable MBL and a soft-tissue improvement, have been published on the Prama
implant.
A study on another implant system demonstrated in both ﬂapless and ﬂapped groups a
marginal bone loss of 0.5 mm after the stressfree healing period, 31 not far from our results.
Similar values were reported in other investigations regarding different implant systems and
the ﬂapless technique. 28, 29 Long-term results
from a randomized clinical trial on a 1-piece
implant with a conical neck shape (similar to the
hyperbolic profile) have recently been published, 32 reporting high success (96.4%) and
survival rates (100%) and acceptable periimplant

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Table 1

Preoperative parameters
Sex

Location

Tooth type
Endodontic treated
adjacent teeth

n

MBL (mm)

Male

28

- 0.47 ± 0.39

Female

34

- 0.45 ± 0.41

Maxilla

48

- 0.40 ± 0.34

Mandible

14

- 0.60 ± 0.47

Anterior

14

- 0.28 ± 0.42

Posterior

48

- 0.54 ± 0.49

No

27

- 0.44 ± 0.47

Yes

35

- 0.46 ± 0.43

Immediate

15

- 0.34 ± 0.46

Early

18

- 0.25 ± 0.22

Delayed

29

- 0.59 ± 0.46

3.80

23

- 0.63 ± 0.44

4.25

31

- 0.44 ± 0.46

5.00

8

- 0.15 ± 0.47

10.0

40

- 0.51 ± 0.44

11.5

22

- 0.41 ± 0.42

Intra-operative parameters
Implant placement

Diameter (mm)

Implant length (mm)
Postoperative parameters
Gingival biotype

Thin

37

- 0.60 ± 0.46

Thick

25

- 0.26 ± 0.41

62

- 0.37 ± 0.41

Total
†

Table 1
Distribution, number of
implants placed (n) and MBL
(mean ± SD) at 12 months.
Table 2
Linear regression results for
implant placement using GEE
with the robust covariance
estimator to account for
correlation in the data. The
implant was used as the unit
of analysis (MBL values
expressed as mean ± SD).
Table 3
Linear regression results for
gingival biotype using GEE
with the robust covariance
estimator to account for
correlation in the data. The
implant was used as the
unit of analysis (MBL values
expressed as mean ± SD).
Table 4a
Multiple linear regression
relating MBL at 12 months to
all variables considered.

One patient dropped out 1 month after implant insertion (2 delayed implants). Total dropout was 1.85%.

Table 2

Immediate

Early

Delayed

T1

- 0.06 ± 0.13Aa

+ 0.01 ± 0.26Aa

- 0.05 ± 0.26Aa

T3

- 0.19 ± 0.30Ab

- 0.14 ± 0.44Ab

- 0.26 ± 0.34Ab

T6

- 0.25 ± 0.22Ab

- 0.16 ± 0.38Ab

- 0.44 ± 0.30Bc

T12

- 0.34 ± 0.04Ab

- 0.25 ± 0.45Ab

- 0.61 ± 0.38Bd

Equal superscript capital letters represent no statistically signiﬁcant difference between groups (P > 0.05).
Equal superscript small letters represent no statistically signiﬁcant time-related difference with times in both groups (P > 0.05).
Table 3

Thin

Thick

T1

- 0.09 ± 0.28Aa

+ 0.03 ± 0.32Aa

T3

- 0.26 ± 0.32Ab

- 0.12 ± 0.53Bb

T6

- 0.40 ± 0.40Ab

- 0.19 ± 0.44Bb

T12

- 0.62 ± 0.37Ac

- 0.26 ± 0.41Bb

Equal superscript capital letters represent no statistically signiﬁcant difference between groups (P > 0.05).
Equal superscript small letters represent no statistically signiﬁcant time-related difference with times in both groups (P > 0.05).
Table 4a

Coefficient

Robust SE

95% CI

P value

Sex

- 0.080

0.625

(- 0.203; - 0.041)

0.196

Location

- 0.024

0.887

(- 0.198; 0.150)

0.787

Tooth type

0.160

0.091

(- 0.019; - 0.339)

0.080

Endodontic adjacent teeth

0.029

0.070

(- 0.108; 0.167)

0.674

Implant placement group

- 0.039

0.049

(- 0.136; 0.058)

0.432

Implant diameter

- 0.146

0.071

(- 0.286; - 0.007)

0.040*

Implant length

0.031

0.068

(- 0.102; 0.165)

0.643

- 0.183

0.056

(- 0.295; - 0.071)

0.001*

Groups
Preoperative parameters

Intra- operative parameters

Postoperative parameters
Gingival biotype

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Groups

Coefficient

Robust SE

95% CI

P value

Implant diameter

- 0.142

0.066

(- 0.278; - 0.006)

0.041*

Gingival biotype

- 0.168

0.063

(- 0.292; - 0.044)

0.008*

Table 4b

* asterisks indicate statistically signiﬁcant differences (p < 0.05)
Table 5a

Pink Esthetic Score (%)
Parameter

Mesial papilla

Distal papilla

Soft-tissue level

Soft-tissue contour

Alveolar process
deﬁciency

Soft-tissue color

Soft-tissue texture

Table 4b
Multiple linear regression after
stepwise selection.

Score

(T0)
Preoperative

T6

T12

0

23.07

0.00

0.00

1

62.3

44.9

45.4

2

7.7

55.1

54.6

0

38.5

0.00

0.00

1

53.8

37.9

40.9

2

7.7

62.1

59.1

0

0.00

0.00

0.00

1

84.6

62.1

36.4

2

15.4

37.9

63.6

0

15.4

0.00

0.00

1

69.2

57.7

31.8

2

15.4

42.3

68.2

0

15.4

0.00

0.00

1

61.5

34.5

22.7

2

23.1

65.5

77.3

0

23.1

0.00

0.00

1

61.5

34.5

22.7

2

15.4

65.5

77.3

0

15.4

0.00

0.00

1

76.9

17.9

4.6

2

7.7

82.1

95.4

Mean ± SD

7.30 ± 2.80

11.06 ± 0.97

11.95 ± 1.04

Median (IQR)

7.5 (6; 9.5)

11 (10.75; 12)

12 (11; 12)

Range [min; max]

[2; 10]

[9; 13]

[10; 13]

T6

T12

PI-M (0 – 4)

1.48 ± 0.59

1.92 ± 0.49

PI-D (0 – 4)

1.59 ± 0.50

2.07 ± 0.52

Table 5a
Pink Esthetic Score of single
implant (expressed as
percentage).

Table 5b

Table 6

PI-M: papilla index of mesial papilla; PI-D: papilla index of distal papilla.
Table 7

Plaque score

Table 5b
Pink Esthetic Score (0–14).

T6

Bleeding on probing
T12

T6

T12

0 (%)

1 (%)

0 (%)

1 (%)

0 (n%)

1 (n%)

0 (n%)

1 (n%)

Table 6
Papilla index (mean ± SD).

Mesial

41.6

58.4

83.3

16.7

83.3

16.7

87.5

12.5

Distal

58.4

41.6

58.4

41.6

87.5

12.5

87.5

12.5

Table 7
Periodontal parameters
around implant restorations
after deﬁnitive loading.

Vestibular

70.8

29.2

70.8

29.2

83.3

16.7

87.5

12.5

Palatal

62.5

37.5

70.8

29.2

100.0

0.0

100.0

0.0

A 0 value indicates that no bleeding on probing/plaque accumulation was present.
A 1 value indicates that bleeding on probing/plaque accumulation was present.

38 Volume 3 | Issue 4/2017

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1-year study of nonsubmerged implants

Figs. 2A–C

Figs. 2D–F

Figs. 2G & H

bone loss (mean MBL: - 0. 30 ± 0.78 mm).
Considering all of the implants placed and evaluated in the present study, a mean MBL of
-0.37 ± 0.41 mm was observed at T12, in agreement with standard success criteria and the
previous recent study. 32
Concerning MBL in relation to placement
timing groups (immediate, early and delayed),
delayed implants showed greater bone loss
(0.61 ± 0.38 mm) at 12 months, while early and
immediate implants showed limited bone loss
(MBL: 0. 25 ± 0.45 mm and 0.34 ± 0.04 mm,
respectively). These results were in accordance
with another previous published study, which
investigated implants with the same surface,
but a different neck morphology (tulip-shaped,
platform-switched implants).33 Bone remodeling procedures are probably different in mature
(delayed group) or immature bone (early and
immediate group), as recently shown in several
in vivo animal studies that tested the ZrTi implant
surface micromorphology used in Prama
implants.34, 35
In all of the patients, periimplant gingival
biotype was evaluated after 12 months from
implant insertion. Thin gingival biotype demonstrated greater bone loss values at 12 months
(P = 0.008). This is in accordance with the ﬁndings of a recent study with a different bone level
implant. 36 Considering all of the parameters

Figs. 2A–H
Maxillary left lateral incisor
that had previously undergone
an apicoectomy. The tooth
presented high-grade mobility
and extraction was scheduled.
(A) Pre-extraction vestibular
view. Atraumatic extraction
was performed, as well
as adequate alveolar socket
debridement. (B) Postextraction view. A Prama
implant was placed nonsubmerged according to the
manufacturer’s instructions;
(C) vestibular and (D) occlusal
views. After 3 months,
impressions were taken (D)
and an abutment was ﬁxed
(E). No second surgeries were
performed to expose the
implant neck. A provisional
crown was cemented free
from tissue compression (F)
and a metal–ceramic crown
was later cemented (G).

evaluated in the statistical analysis, gingival
biotype was found to greatly affect MBL. 37
Berglundh and Lindhe demonstrated in an
animal study that a thin gingival biotype may
affect crestal bone stability. 38 Thus, also for this
type of implant, postoperative gingival biotype
may be considered one of the most important
clinical parameters that may affect MBL at least
after 12 months from placement. Soft-tissue
parameters evidenced an improvement from
6 to 12 months, showing a soft-tissue maturation
over time. The mean PES was 11.09 at 6 months
(2 months from deﬁnitive loading) and improved
at the 12-month follow-up, showing a mean
value of 11.95. This conﬁrms that soft-tissue
modiﬁcations occur during the ﬁrst months of
loading. Similar PES values are reported in the
literature. In a 12-month clinical study, the PES
of 2 different implant treatment strategies was
evaluated (immediate implants versus conventional loading). Their 12-month mean values
were 10.33 and 10.35, respectively.1
Interestingly, in our study, a high prevalence
of the maximum soft-tissue color score was
found (65 . 51% at 6 months and 77. 28 % at
12 months), despite the presence of an unfavorable preoperative score (approximately a quarter
of the preoperative soft-tissue color presented
a 0 score). The yellow Prama hyperbolic neck,
together with the presence of a thick gingival

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1-year study of nonsubmerged implants

Preoperative

Figs. 3A–E
Periapical radiograph
sequence of immediate
implant placement restoring
a fractured endodontically
treated lateral incisor.
(A) Preoperative radiograph.
(B) Post-extraction radiograph.
(C) A 3.8 × 11.5 mm implant
was placed nonsubmerged
immediately after extraction.
A stable MBL was observed
at 6 months (D) and
it remained stable at the
12-month follow-up (E).

Post-extraction

Immediate placement

biotype (60.19%), may explain these results.
Demonstrating a healthy gingiva with no inﬂammation, 95.44% of the implants showed an optimal soft-tissue texture. In order to further consolidate these results, BoP at the 12-month
evaluation was negative in approximately 90%
of the periimplant sites evaluated.
It is known that plaque accumulation around
implant restorations may induce soft-tissue
chronic inﬂammation, gingival bleeding and, in
the long-term, periimplant bone loss. 39 Little
plaque accumulation was present around
implant sites at 12 months. Sites totally free from
plaque ranged from 58.4% to 83.3%. The 3 mm
machined surface of the implant neck, the crown
design and the hygienic recall program may also
have contributed to this result. It has been
reported that machined surfaces may reduce
plaque and bacteria accumulation around the
implant emergence proﬁle.40
Limitations of the study are represented by
the small sample size and the short-term followup. Thus, results should be interpreted with caution. Further investigations in the long term and
with a larger study cohort may conﬁrm our results.
The Prama implant, following BOPT principles,
allows the clinician to model the soft tissue and
have the gingival margin level with the periimplant tissue in the same way as natural
tooth-supported restorations, as no ﬁnishing
line is present. Moreover, the implant emergence proﬁle with the hyperbolic conﬁguration
allows creation of the crown ﬁnishing line corresponding to the gingival margin or to the
periimplant sulcus without any tissue compression. Within the limitations of this preliminary
study, the results demonstrated some advantages that may be the result of simpler prosthetic management:
40 Volume 3 | Issue 4/2017

Figs. 3A–E

After 6 months

After 12 months

1. use of a noninvasive ﬂapless technique with

no second surgery for neck exposure and no
need for a healing screw;
2. possibility of positioning the crown margin at
different levels close to the periimplant sulcus
and corresponding to the (yellow) implant
neck;
3. implant–abutment connection above the gingival level;
4. minimal trauma and stress on the soft tissue
during prosthetic procedures to preserve the
MBL;
5. adequate control to avoid excess cement.
Two drawbacks must be reported:
1. Surgical implant positioning is critical, as no
modiﬁcation of the abutment axis may be
later performed, so a partial lack of abutment
versatility must be included.
2. The implant requires adequate distance from
the opposite antagonist tooth, as the implant
neck plus abutment requires at least 5 mm
plus crown restoration.
Conclusion
The use of a 2-piece nonsubmerged implant
with a hyperbolic neck proﬁle offers a new
approach to the management of soft and hard
tissue. In this, the prosthetic preparation makes
it possible to preserve a good MBL, to reduce
healing time, to perform a minimally invasive
surgery, to avoid additional re-entry and to have
fewer complications.
Competing interests
The authors declare that they have no competing interests.

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1-year study of nonsubmerged implants

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3-year results.
→ Clin Oral Implants Res.
2009 Aug;20(8):802–8.
23.
Fürhauser R, Florescu D, Benesch T,
Haas R, Mailath G, Watzek G. Evaluation
of soft tissue around single-tooth implant
crowns: the pink esthetic score.
→ Clin Oral Implants Res.
2005 Dec;16(6):639–44.
24.
Jemt T. Regeneration of gingival papillae
after single-implant treatment.
→ Int J Periodontics Restorative Dent.
1997 Aug;17(4):326–33.
25.
Cosyn J, Eghbali A, Hermans A, Vervaeke
S, De Bruyn H, Cleymaet R. A 5-year
prospective study on single immediate
implants in the aesthetic zone.
→ J Clin Periodontol.
2016 Aug;43(8):702–9.
26.
Rogers WH. Regression standard errors
in clustered samples.
→ Stata Technical Bulletin.
1993 May;13:19–23.
27.
Chrcanovic BR, Albrektsson T,
Wennerberg A. Flapless versus
conventional ﬂapped dental implant
surgery: a meta-analysis.
→ PLoS ONE.
2014 Jun 20;9(6):e100624.
28.
De Bruyn H, Atashkadeh M, Cosyn J,
van der Velde T. Clinical outcome and
bone preservation of single TiUnite
implants installed with ﬂapless or ﬂap
surgery.
→ Clin Implant Dent Relat Res.
2011 Sep;13(3):175–83.
29.
Rousseau P. Flapless and traditional
dental implant surgery: an open,
retrospective comparative study.
→ J Oral Maxillofac Surg.
2010 Sep;68(9):2299–306.
30.
Galindo-Moreno P, León-Cano A,
Ortega-Oller I, Monje A, O’Valle F, Catena
A. Marginal bone loss as success criterion
in implant dentistry: beyond 2 mm.
→ Clin Oral Implants Res.
2015 Apr;26(4):e28–34.

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31.
Nickening HJ, Wichmann M, Schlegel
KA, Nkenke E, Eiter S. Radiographic
evaluation of marginal bone levels during
healing period, adjacent to parallel-screw
cylinder implants inserted in the
posterior zone of the jaws, placed with
ﬂapless surgery.
→ Clin Oral Implants Res.
2010 Dec;21(12):1386–93.
32.
Froum SJ, Khouly I. Survival rates and
bone and soft tissue level changes around
one-piece dental implants placed with a
ﬂapless or ﬂap protocol: 8.5-year results.
→ Int J Periodontics Restorative Dent.
2017 May–Jun;37(3):327–37.
33.
Prati C, Zamparini F, Pirani C, Gatto MR,
Piattelli A, Gandolﬁ MG. Immediate early
and delayed implants: a 2-year
prospective cohort study of 131
transmucosal ﬂapless implants placed
in sites with different pre-extractive
endodontic infections.
→ Implant Dent.
2017 Oct;26(5):654–63.
34.
Mainetti T, Lang NP, Bengazi F, Sbricoli L,
Soto Cantero L, Botticelli D. Immediate
loading of implants installed in a healed
alveolar bony ridge or immediately after
tooth extraction: an experimental study
in dogs.
→ Clin Oral Implants Res.
2015 Apr;26(4):435–41.
35.
Mainetti T, Lang NP, Bengazi F, Favero V,
Soto Cantero L, Botticelli D. Sequential
healing at implants installed immediately
into extraction sockets. An experimental
study in dogs.
→ Clin Oral Implants Res.
2016 Jan;27(1):130–8.
36.
Puisys A, Linkevicius T. The inﬂuence
of mucosal tissue thickening on crestal
bone stability around bone-level
implants. A prospective controlled
clinical trial.
→ Clin Oral Implants Res.
2015 Feb;26(2):123–9.
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Zweers J, Thomas RZ, Slot DE, Weisgold
AS, Van der Weijden FG. Characteristics
of periodontal biotype, its dimensions,
associations and prevalence: a
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→ J Clin Periodontol.
2014 Oct;41(10):958–71.
38.
Berglundh T, Lindhe J. Dimension of
the periimplant mucosa. Biological width
revisited.
→ J Clin Periodontol.
1996 Oct;23(10):971–3.
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Renvert S, Quirynen M. Risk indicators
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→ Clin Oral Implants Res.
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→ Clin Oral Implants Res.
2015 Jul;26(7):851–7.

Volume 3 | Issue 4/2017 41

[42] =>

Digital wax prototypes: A clinical report

Digital approach to the fabrication of
a wax prototype for full-mouth
rehabilitation of a worn dentition:
A clinical report

Abstract
Background
Christian Brenes,a Courtney S. Babb,a Sompop Bencharit,b
Mario Romeroc & Roger Arced
a

Department of General Dentistry, Dental College of
Georgia, Augusta University, Augusta, Ga., U.S.
b
Department of General Dentistry, Virginia Commonwealth University, Richmond, Va., U.S.
c
Department of Restorative Sciences, Dental College
of Georgia, Augusta University, Augusta, Ga., U.S.
d
Department of Periodontics, Dental College of Georgia,
Augusta University, Augusta, Ga., U.S.

Corresponding author:
Dr. Christian Brenes
Department of General Dentistry
Dental College of Georgia
Augusta University
1120 15th St
Augusta, GA 30912
U.S.

This article describes a technique of the creation of a virtual wax-up and
design of a wax prototype used as a pattern for the fabrication of posterior metal–ceramic and anterior pressed lithium disilicate restorations
for a patient with a severely worn dentition.
Materials and methods

During the rehabilitation of a patient, computer-aided design (CAD) can
be used as a tool to verify marginal adaptation, occlusion and contact
points before pressing or fabricating the ﬁnal restorations. The prototypes work as an esthetic try-in that can be modiﬁed easily if necessary.
Results

After proper veriﬁcation, there were no marginal discrepancies and no
occlusal modiﬁcation was required, nor were contact points adjusted
during ﬁnal delivery. After a 1-year follow-up, the patient reported no
complications.

cbrenesvega@augusta.edu

Conclusion

How to cite this article:
Brenes C, Babb CS, Bencharit S, Romero M, Arce R.
Digital approach to the fabrication of a wax prototype
for full-mouth rehabilitation of a worn dentition:
A clinical report.
J Oral Science Rehabilitation. 2017 Dec;3(4):42–47.

Computer-aided design/computer-aided manufacturing has brought
many advantages to restorative dentistry, including producing predictable restorations in less time compared with traditional methods of fabrication. In this comprehensive prosthodontic rehabilitation of a severely
worn dentition, the virtual diagnostic wax-up and ﬁnal restoration CAD
took less than 60 min for each procedure. Additionally, the wax prototype
is a multipurpose restorative tool, as it serves as both an esthetic and
functional try-in device and as a wax pattern for the ﬁnal restoration.
Keywords

CAD/CAM, wax prototype, smile design, digital design, lithium disilicate,
virtual wax-up.
42 Volume 3 | Issue 4/2017

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Digital wax prototypes: A clinical report

Introduction
Tooth wear is a multifactorial process that can be
attributed to the mechanisms of attrition, erosion
and abrasion1 and can adversely impact patient
satisfaction with appearance, pain levels, oral
comfort and chewing capacity.2 Patients tend to
seek help from dental professionals at a more
advanced stage of wear, especially when it has
esthetically compromised the incisal edges of the
anterior teeth.3 Alteration in clinical crown height
may be necessary to improve esthetics, and this
is often facilitated by increasing the vertical
dimension of occlusion (VDO).4 When changing
the incisal position restoratively, trial restorations
should be used as a guide for the patient to experience function, comfort, stability and esthetics
at the new increased VDO.5 Necessary changes
can then be made prior to fabrication of the permanent restorations, instead of having the ﬁnal
restorations created without any veriﬁcation process, which can potentially lead to minor or major
adjustments and possible defects of the ceramic
restorations. The wax prototype can easily be
modiﬁed and used as a template for fabrication.
The advances in computer-aided design/
computer-aided manufacturing (CAD/CAM) technology over the recent years have led to an evolution in restorative dentistry. Digital dentistry can
be useful in full-mouth rehabilitation, as it has
increased the ability of the dental team to efficiently create, communicate and digitally store
smile designs6 and wax-ups. The ﬁnal restorations
can be designed and milled based on the digital
smile design, or the same smile design can be used
to create prototypes of the ﬁnal restorations for
veriﬁcation purposes. While scanning and milling
CAD/CAM restorations have been shown to produce restorations of acceptable marginal ﬁt below
100 μm,7 recent studies have shown that the combination of a conventional polyvinylsiloxane
impression method and the pressed fabrication
technique produces the most accurate 3-D and
2-D marginal ﬁt.8
The purpose of this article is to describe a technique of the creation of a virtual wax-up and
design of a wax prototype used as a pattern for
the fabrication of posterior metal–ceramic and
anterior pressed lithium disilicate restorations for
a patient with a severely worn dentition.
Clinical report
A 66-year-old woman presented to the Department of Prosthodontics at the University of

North Carolina at Chapel Hill School of Dentistry,
Chapel Hill, N.C., U.S., with the chief complaints
of missing teeth and worn dentition (Fig. 1). Clinical examination found multiple teeth with moderate to severe attrition and erosion. The patient
stated that she drank lemonade daily and had
been without posterior teeth for over 5 years
(Figs. 2 & 3). Previous dental history established
replacement of missing teeth with a mandibular
removable partial denture, which the patient had
never tolerated owing to movement and food
accumulation. The patient presented with excellent periodontal status and hygiene, and no endodontic lesions or pathologies. After evaluation
of the patient records, a digital smile design was
created to evaluate the possible esthetic outcome of the treatment to include the midline,
occlusal plane and ideal proportions, position,
symmetry and shape of the anterior teeth.
Incisal edge position was determined ﬁrst9 by
adding composite to the maxillary central incisors and evaluating the lips at rest and during
smiling following the Vig and Brundo parameters of lip display.10 After the length had been
established, a digital smile design protocol was
created and width was determined using a proportion close to 80% of the length.11 The maxillary lateral incisors, canines and premolars were
designed following the curvature of the lower
lip and with relative tooth sizes close to the
golden percentage (Fig. 4).12
The articulated casts were scanned using a
3-D scanner (3Shape D700, 3Shape, Copenhagen, Denmark). The 3-D image of the smile
design was imported into the design software
(Smile Composer, 3Shape) to follow the same
design during the virtual diagnostic wax-up. The
virtual diagnostic wax-up was created at an
increased VDO (Fig. 5).
The occlusion was veriﬁed in the CAD software, and stereolithographic ﬁles were sent to
the Microdental laboratory, Raleigh, N.C., U.S.,
to mill replicas in wax and in polymethyl methacrylate (PMMA) to be used as shell provisionals
with a dry milling machine (Zenotec mini,
Wieland Dental, Pforzheim, Germany).
Upon completion of the diagnostic wax-up,
the dental team developed a treatment plan that
included implant-supported ﬁxed partial dentures for the missing mandibular left second
premolar through ﬁrst molar and mandibular
right second premolar through second molar,
full-coverage crowns for the mandibular left
canine and right ﬁrst premolar, full-coverage
crowns for the maxillary anterior teeth, and a

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Digital wax prototypes: A clinical report

Fig. 1

Fig. 2

Fig. 4

Fig.3

Fig. 5

Fig. 1
Preoperative smile view. Note
attrition on incisal edges.
Fig. 2
Preoperative occlusal view of
maxillary teeth. Note attrition
on incisal edges and erosion
on lingual surfaces of anterior
teeth.
Fig. 3
Preoperative occlusal view of
mandibular teeth.
Fig. 4
Digital smile design,
establishing maxillary incisal
edge position.
Fig. 5
Completed virtual diagnostic
wax-up at increased VDO after
digital smile design.

ﬁxed partial denture from the maxillary right
second molar to second premolar.
Based on the diagnostic wax-up, a radiographic stent was fabricated and used to perform a cone beam computed tomography scan
for implant placement planning. A surgical guide
based on the milled wax-up was used to place 2
4.1 × 10.0 mm implants (Tapered Screw-Vent
Implants, Zimmer Biomet, Warsaw, Ind., U.S.)
44 Volume 3 | Issue 4/2017

in the position of teeth #3.4 and 4.5 and two
4.75 × 10.0 mm Tapered Screw-Vent implants in
the positions of teeth #3.6 and 4.7. Three months
later, a second-stage surgery was performed to
uncover the implants and healing abutments
were placed for a period of 2 weeks.
At the preparation appointment, teeth #1.7
through 2.4 and teeth #3.3 and 4.4 were prepared for full-coverage anterior lithium disilicate

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Digital wax prototypes: A clinical report

Fig. 7

Fig. 6

Fig. 6
Milled wax prototype try-in,
smile view.
Fig. 7
Milled wax prototype try-in,
maxillary occlusal view.
Fig. 8
Milled wax prototype try-in,
mandibular occlusal view.
Fig. 9
Final restorations cemented.

Fig. 9

Fig. 8

Fig. 10
Final restorations, maxillary
occlusal view.
Fig. 11
Final restorations, mandibular
occlusal view.

Fig. 10

Fig. 11

crowns (IPS e.max Press, Ivoclar Vivadent, Ellwangen, Germany) and posterior metal–ceramic
crowns. A double-cord impression technique for
prepared teeth and a closed-tray impression
technique with the impression abutments in
position for the implants were performed to produce ﬁnal impressions using a silicone impression material (Aquasil Ultra, Dentsply Sirona,
York, Pa., U.S.). The milled PMMA provisionals,
sectioned into sextants, were relined with
self-curing acrylic resin (Jet Acrylic, Lang Dental,
Wheeling, Ill., U.S.). Casts made from the ﬁnal
impressions were cross mounted with casts of
the provisional restorations. All of the dies and
casts were scanned with the 3Shape D700 for
custom titanium abutments (Atlantis, Dentsply
Sirona, York, Pa., U.S.) to be designed based on
a copy of the virtual wax-up.

The custom abutments were manufactured, and
the CADs of the ﬁnal restorations were then
copy-milled into wax prototypes by the dental
laboratory with the purpose of using them as
templates for the ﬁnal restorations. The milled
wax prototype was tried in for an occlusal and
esthetic evaluation (Figs. 7 & 8). Both arches
were evaluated and no occlusal adjustments
were necessary in centric relation and during
excursive movements. Minimal reduction of the
incisal edges was performed to make the esthetics more age-appropriate.13 The case was sent
to the dental laboratory for the fabrication of
the ﬁnal restorations. Final characterization was
done, followed by glazing and polishing (Table 1).
At delivery, the posterior metal–ceramic restorations and anterior IPS e.max pressed
restorations were approved by the patient for

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Digital wax prototypes: A clinical report

Table 1
Summary of the steps in the
wax prototype technique.

Table 1

Clinical step

Procedure

Preliminary impressions are taken and a traditional or digital diagnostic wax-up is made.

Teeth are prepared and provisionalized based on the diagnostic wax-up and following
the guidelines for the type of material chosen.

A ﬁnal traditional polyvinylsiloxane impression or digital impression is taken and used
to design the ﬁnal restorations.

A traditional digital bite record in centric relation is taken to mount the case.

The case is digitally designed and wax patterns are milled for veriﬁcation purposes.

The wax patterns are modiﬁed if needed by selective grinding or wax addition.

Restorations are used to press or scan-copy-mill the ﬁnal restorations.

Restorations are delivered with no expected modiﬁcations required.

esthetics, and the restorations were veriﬁed for
marginal ﬁt, proximal contacts and occlusion.
No adjustments were needed. Implant abutments were torqued to the manufacturer-recommended values, and the posterior restorations were cemented with resin cement (RelyX
Unicem, 3M ESPE, Seefeld, Germany). The anterior crowns were bonded using resin cement
(Variolink Esthetic, Ivoclar Vivadent; Figs. 9–11).
The patient was very satisﬁed with the treatment outcome and was followed for a period of
6 months, during which time she reported no
complications or complaints.

Discussion
This clinical situation illustrated a patient with a
severely worn dentition who sought dental treatment after the maxillary anterior incisal edges
had become compromised, thereby affecting
esthetics. Owing to the loss of clinical crown
height of the maxillary incisors subsequent to
erosion and attrition, the decision was made to
increase the VDO in order to provide adequate
space for esthetically pleasing restorations. The
patient was amenable to comprehensive ﬁxed
prosthodontic rehabilitation because of missing
teeth and her inability to tolerate a removable
prosthesis. The diagnostic wax-up had revealed
very minor issues that the patient was not interested in addressing at the time of the treatment;
thus, she did not desire whitening or direct restorations on the mandibular incisors.
46 Volume 3 | Issue 4/2017

Traditionally, diagnostic wax-ups done by hand,
by the clinician or technician, have been known
to be a time-consuming step in the treatment
planning process. The advantage of incorporating digital dentistry into the workﬂow of pressed
restorations is that it provides a more consistent
result in diagnostic wax-ups obtained through
the use of CAD libraries, instead of relying on
freehand wax-ups. Additionally, the time needed
for the creation of a diagnostic wax-up is signiﬁcantly reduced; in this situation, the virtual
wax-up was created in less than 60 min.
The employment of CAD/CAM to create a
milled wax prototype of the ﬁnal restorations is
a revolutionary use of the technology for both
dentists and dental technicians. Not only can it
be used as an esthetic and functional try-in tool
by the clinician to verify marginal adaptation,
occlusion and esthetics prior to delivery of the
ﬁnal restorations, but it also can serve as essentially a wax pattern for the fabrication of pressed
or metal–ceramic restorations or a scan copy
for milled restorations if any modiﬁcations are
made. The wax used in CAD/CAM milling discs
is very different than traditional dental wax. In
order to resist the heat produced by the burs
during milling, these waxes are developed as a
hard hybrid plasticized wax blend, with a melting
point between 101.667 and 121.111 °C.14 During
try-in, the shape, marginal ﬁt, occlusion and
proximal contacts of the restorations can be
veriﬁed, because the rigidity of the wax allows
for this. If adjustments are needed, the wax can
be modified accordingly with heat or rotary

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Digital wax prototypes: A clinical report

instrumentation. One limitation is that the wax
prototypes do not have enough retention, a
problem with restoration try-ins. Denture adhesive or ﬁt checker (GC America, Tokyo, Japan)
can be used to minimize this issue. The wax prototype can then be sent to the laboratory technician, who can then invest it as he or she would
a wax pattern created through the traditional
waxing process.
This wax prototype technique presents a
unique melding of traditional and digital dental
processes. CAD/CAM technology is used for
designing and milling the wax prototype, which
is then used as a traditional wax pattern to create
the pressed, metal–ceramic or milled ﬁnal restorations. Using this method in this clinical situation allowed for all of the restorations to be
made in the same method, even though different
materials (lithium disilicate for the anterior and
metal–ceramic for the posterior) were used,
making for a more streamlined production process. When used to create the ﬁnal restoration,
the wax prototype works as a template, to avoid
modifying the ﬁnal restoration during the delivery. In many cases, clinicians need to modify the
restoration by grinding and polishing. Depending
on the modiﬁcation process, the ﬁnal restoration
can end up with internals fracture lines developed as a consequence of grinding the ceramic
material that are not recognized by the clinician

and can jeopardize the treatment plan and the
life span of the restoration.

Conclusion
CAD/CAM has brought many advantages to
restorative dentistry, including producing predictable restorations in less time compared with traditional methods of fabrication. In this comprehensive prosthodontic rehabilitation of a severely
worn dentition, the virtual diagnostic wax-up and
ﬁnal restoration CAD took less than 60 min for
each procedure. Additionally, the wax prototype
is a multipurpose restorative tool, as it serves as
both an esthetic and functional try-in device and
as a wax pattern for the ﬁnal restoration.

Competing interests
The authors declare that they have no conﬂict
of interest regarding the materials used in the
present study.

Acknowledgments
The authors thank Dr. William Bracket for his
assistance in reviewing this article.

References
1.
Johansson A, Johansson AK, Omar R,
Carlsson GE. Rehabilitation of the worn
dentition.
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5.
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and how.
→ Br Dent J.
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2.
Al-Omiri MK, Lamey PJ, Clifford T.
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6.
Ferencz JL. Increasing VDO and the
use of CAD/CAM: prosthodontic
principles and the full-mouth reconstruction.
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2013 Summer;29(2):86–96.

3.
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monolithic restorations and full-mouth
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patient with a past history of bulimia:
the modiﬁed three-step technique.
→ Int J Esthet Dent.
2016 Spring;11(1):36–56.
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Wassell RW, Steele JG, Welsh G.
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1998 Dec;48(6):571–81.

7.
Reich S, Trentzsch L, Gozdowski S, Krey
KF. In vitro analysis of laboratoryprocessed and CAD/CAM-generated
occlusal onlay surfaces.
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2009 Nov–Dec;22(6):620–2.

8.
Anadioti E, Aquilino SA, Gratton DG,
Holloway JA, Denry I, Thomas GW,
Qian F. 3D and 2D marginal ﬁt of pressed
and CAD/CAM lithium disilicate crowns
made from digital and conventional
impressions.
→ J Prosthodont.
2014 Dec;23(8):610–7.
9.
Chiche GJ, Aoshima H. Functional
versus aesthetic articulation of maxillary
anterior restorations.
→ Pract Periodontics Aesthet Dent.
1997 Apr;9(3):335–42; quiz 343.

12.
Murthy BV, Ramani N. Evaluation of
natural smile: Golden proportion, RED
or Golden percentage.
→ J Conserv Dent.
2008 Jan;11(1):16–21.
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Freedman GA. Contemporary Esthetic
Dentistry. 1st ed.
→ St. Louis: Mosby/Elsevier; 2012. 461 p.
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Denry I, Holloway JA. Ceramics
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→ Materials (Basel).
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10.
Vig RG, Brundo GC. The kinetics of
anterior tooth display.
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Wolfart S, Thormann H, Freitag S, Kern
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[48] =>

Proximity of mandibular first and second molars to IAC

Is there a justification for cone beam
computed tomography for assessment
of proximity of mandibular first
and second molars to the inferior
alveolar canal: A systematic review

Abstract
Objective
Shahnawaz Khijmatgar,a Chitta Chowdhury,a Kumuda Rao,b
Sanal Thankappan Swarnadhaic & Nayak Krishnad
a

Department of Oral Biology and Genomic Studies, A.B.
Shetty Memorial Institute of Dental Sciences, Nitte
University, Deralakatte, India
b
Department of Oral Medicine and Radiology, A.B. Shetty
Memorial Institute of Dental Sciences, Nitte University,
Deralakatte, India
c
Department of Statistics, K.S. Hegde Medical College and
Hospital, Nitte University, Deralakatte, India
d
Department of Orthodontics and Dentofacial Orthopaedics, A.B. Shetty Memorial Institute of Dental Sciences,
Nitte University, Deralakatte, India

Corresponding author:
Dr. Shahnawaz Khijmatgar
Department of Oral Biology and Genomic Studies
A.B. Shetty Memorial Institute of Dental Sciences
Nitte University
Deralakatte—575018
Mangalore, Karnataka
India
khijmatgar.s@gmail.com
How to cite this article:
Khijmatgar S, Chowdhury C, Rao K, Thankappan
Swarnadhai S, Krishna N. Is there a justiﬁcation for
cone beam computed tomography for assessment
of proximity of mandibular ﬁrst and second molars to
the inferior alveolar canal: A systematic review.
J Oral Science Rehabilitation. 2017 Dec;3(4):48–56.

The objective of this review was to determine the distance from the apices
of mandibular ﬁrst and second molars to the inferior alveolar canal (IAC)
using cone beam computed tomography (CBCT).
Data sources and study selection

Articles published between the period of 1988 to 2016 were included.
This review included mandibular ﬁrst and second molar studies that
sought to observe proximity to the IAC using 3-D imaging modalities.
The authors developed speciﬁc search strategies for PubMed, Scopus
and Web of Science and evaluated the methodological quality of the
included studies using criteria from the PICO protocol. Articles that aimed
at determining the distance of the apices of mandibular ﬁrst or second
molars or both from the IAC and that used CBCT as an imaging modality
were included in the study.
Results

This review identified an average mean distance of 7.3 mm (range:
0.00–14.71 mm) from the apices of mandibular ﬁrst and second molars
from the IAC. The mean difference (IV, ﬁxed, 95% CI) for ﬁrst molars in
women was 0.29 (95% CI: 0.11, 0.48) and for second molars was 0.50
(95% CI: -0.00, 1.01) compared with 0.31 (95% CI: 0.08, 0.54) for ﬁrst
molars in men and 0.23 (95% CI: -0.51, 0.98) for second molars on both
sides of the mandible.
Conclusion

We can conclude that an approximate average mean distance of 7.3 mm
is present between the IAC and the apices of mandibular molars.
Keywords

Radiology, CT imaging, imaging, surgical techniques, occlusion, stomatognathic physiology.
48 Volume 3 | Issue 4/2017

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[49] =>

Proximity of mandibular first and second molars to IAC

Introduction
The inferior alveolar canal (IAC) runs in an
S-shaped pattern in the mandible. Factors like
age, race, sex and the anatomy of the mandible
inﬂuence its location. The IAC contains a nerve
that, along with the inferior alveolar artery and
vein, innervates the posterior teeth through the
IAC before splitting into incisive and mental
components that innervate the mandibular
anterior teeth, lower lip and gingiva. All of these
factors have clinical signiﬁcance with reference
to the distance from the ﬁrst and second molars
to the IAC, more so than the distance from the
third mandibular molar. These facts are well
documented with regard to the proximity of the
IAC to the apices of the mandibular ﬁrst molars.
The inferior alveolar nerve (IAN) is the most
commonly injured nerve—about 64.4% of injuries occur from trauma due to implant placement.1 While evaluating the beneﬁts and outcomes of dental treatment, the dentist should
be aware of the position of the IAN/IAC with
respect to the apices of the mandibular molars.2
Injuries to the IAC are mostly iatrogenic. 3
Dental clinical procedures such as endodontics,
tooth extraction, implant placement and other
surgical procedures in the area of the ﬁrst and
second molars are the major causes of iatrogenic
injury to the branches of the trigeminal nerve
within the IAC. 4 In 40% of the cases, injury is
due to dental implants,1 followed by 1–10% due
to endodontic procedures (Fig. 1). Other types
of injury to the IAN occur through mechanical
trauma caused by overinstrumentation, extrusion of chemical agents such as irrigants,
intracanal medicaments, root ﬁlling materials,
the presence of foreign material or thermal
injury during endodontic procedures.1, 5 The consequence of injury to the nerve is postoperative
paresthesia or anesthesia that may be transient
or permanent. The mandibular second molar
apices have been reported to be the closest to
the IAN compared with the premolars and ﬁrst
molar1 and hence more prone to injury.
In order to interpret these problems, clinicians rely on various methods of radiographic
examination. Information regarding teeth and
their associated anatomy, including root canal
morphology, is commonly obtained from conventional imaging modalities such as intraoral
radiographs, cephalograms, dental panoramic
tomograms and cone beam computed tomography (CBCT). The conventional signs of proximity of the IAN to molars include root

narrowing, root deﬂection and biﬁd apices, as
well as root canals that show diversion, narrowing or loss of lamina dura. 4 Hence, the newer
method of 3-D imaging is considered to be the
most reliable aid in assessing the relationship of
roots to the IAN because of its accuracy, efficiency and effectiveness.5
The objective of this review was to determine
the proximity of mandibular ﬁrst and second
molar apices to the IAC and to determine the
justiﬁcation of the use of CBCT of mandibular
ﬁrst and second molars to assess treatment
outcome. The results of this review will enable
clinicians to estimate the distance between the
IAN/IAC and the apices of mandibular ﬁrst and
second molars on the basis of various published
studies. The information obtained can be applied
during various dental procedures to estimate
the potential risk of any injury to the IAN/IAC
due to varying dental procedures in the mandibular posterior areas.

Materials and methods
We used secondary data and included studies
that considered mandibular ﬁrst and second
molar apices in determining proximity to the IAC
using 3-D imaging. We did not include the studies for analysis from 2-D imaging, but considered
them to determine the difference between 3-D
and 2-D imaging in distances recorded.
Search methods and identification
and selection of studies

We carried out a search of the literature using
the PubMed, Web of Science and Scopus databases. A total of three independent searches
were carried out. The study used reports of
CBCT scans from 1986 to 2016 that included
ﬁrst and second mandibular molars and their
distance to the IAC in different populations and
considering age, sex and various other factors.
The key terms used for extracting the relevant
articles were “cone beam computed tomography” or “cbct” or “CBCT dental” or “cone beam
CT dental” or “cone beam dental” and “inferior
alveolar canal” or “IAN canal” or “IAN” and “lower
molar” or “lower ﬁrst molar” or “lower second
molar” or “mandibular molar”. The process of
article inclusion and exclusion was according to
the PRISMA protocol (Fig. 2).
The initial search of all three databases
yielded 94 articles. Later, after reviewing the

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Proximity of mandibular first and second molars to IAC

Fig. 1

Fig. 1
Prevalence of causes of
inferior alveolar nerve injury.

titles and abstracts, 74 articles found to be duplicates and not to meet the criteria were eliminated. Ten articles were included for full-text
reading and one study was eliminated. The 3-D
studies Hiremath et al., 6 Kawashima et al.,1
Chong et al.,2 Bürklein et al.,7 Adigüzel et al.8 and
Simonton et al.9 were included for further data
analysis. The 2-D studies Tilotta-Yasukawa et
al.10 and Littner et al.11 were included for the sake
of comparison. A summary of the included
articles found in the search of the databases is
provided in Table 1.

Assessment of risk of
bias in included studies

Based on the design and content of the selected
studies, their quality was evaluated independently by two reviewers (SK and STS). The
risk of bias assessment was not possible owing
to nonavailability of clinical trials and the nature
of the study. It was only possible to extract data
from secondary data.

Results
Data collection and analysis

The data were the year of publication, author,
country of study, type of imaging modality,
model of CBCT machine, technical speciﬁcations
and the distances in millimeters measured from
the apices of mandibular ﬁrst and second molars
to the IAC. Meta-analyses were planned only
when sufficient similarities were found among
the included studies with regard to the side of
mandible, that is, right or left; mesial or distal
root; ﬁrst or second molar; male or female. Subgroup analyses were conducted for different
quadrants of the mandible, sex and tooth. Mean
differences and standard deviations were used
to summarize the data in the studies with continuous outcomes. Heterogeneity was assessed
using the I 2 statistic. A forest plot was constructed using Review Manager (Version 5.3,
Nordic Cochrane Centre, Cochrane Collaboration, Copenhagen, Denmark).
50 Volume 3 | Issue 4/2017

Among 94 articles, the authors selected 9 articles, including 7studies that used a 3-D imaging
modality, for further analysis. Since the review
made use of secondary data, it was not possible
to comment on risk of bias. The sample size
ranged from 216 to 999 adults. This review
identiﬁed an average mean distance of 7.3 mm
(range: 0.00–14.71 mm) from the apices of mandibular ﬁrst and second molars to the IAC. The
mean difference (IV, ﬁxed, 95% CI) on both sides
of the mandible for ﬁrst molars in women was
0.29 (95% CI: 0.11, 0.48) and for second molars
was 0.50 (95% CI: -0.00, 1.01) compared with
0.31 (95% CI: 0.08, 0.54) for ﬁrst molars in men
and 0. 23 (95 % CI: - 0. 51 , 0. 98) for second
molars. The proportion of women to men whose
ﬁrst or second molars were closely located to
the IAC was 3 to 1. According to some studies,
the distance was smaller in young individuals.
The meta-analysis of the articles that had

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Fig. 2

Fig. 2
Schematic representation of
the article selection process.

Titles and abstracts obtained from electronic database
(PubMed = 75; Scopus = 5; Web of Science = 14)

Excluded studies, not
relevant (n = 74)
Relevant studies after assessment
of titles and abstracts (n = 20)

Excluded studies after scrutiny
of full texts (n = 10)
Suitable studies after scrutiny of full
texts (n = 10)
Articles excluded based on ambiguity
of content and inadequate information
(n = 1)

Full-text articles included for
systematic review (n = 9)

similar characteristics and data is illustrated in the average distance was 1.31–14.71 mm in men
Figures 3 to 11 .
and 0.00 – 6.90 mm in women. 6 A study by
Adigüzel et al. on a Turkish population found that
the distance from the IAN to ﬁrst molars in men
Discussion
was 5.1 mm mesially and 4.8 mm distally and for
women was 4.4 mm mesially and approximately
According to the studies in Table 1, the distance 4.1 mm distally. 8 The difference in distance
of the IAN from the apices of ﬁrst and second between men and women may be due to men
molars ranged from 0.00 to 14.71 mm. The aver- generally having a larger bone structure and
age mean distance was found to be 7.3 mm. consequently a greater distance between apices
These findings were from both 2-D and 3-D and ﬁrst and second molars.7 Hence, clinically,
imaging techniques (Fig. 12). The distance varied there will be a greater possibility of iatrogenic
according to factors such as sex, age and race nerve damage in women compared with men.1
(Table 2).
Sex

Age

Recent studies Hiremath et al. and Adigüzel et
al. considered sex as one of the factors in their
studies that may inﬂuence proximity of the IAN
to the apices of ﬁrst and second molars.6, 8 These
studies found that the distance from the IAN to
the apices of ﬁrst and second molars was smaller
in women than in men. 6, 7 Studying an Indian
population, Hiremath et al. found that the distance of the mesial apices of ﬁrst molars from
the IAN was 1 . 46 –13 . 2 mm in men and
0.93–8.03 mm in women, and for second molar,

Bürklein et al. and Adigüzel et al. considered age
also as a factor in their studies to determine
proximity of the IAN to the apices of ﬁrst, second
and third molars.7, 8 In a study conducted on a
German population, Bürklein et al. sought to
determine the proximity of the IAN to the apices
of mandibular ﬁrst and second molars.7 They
found that the distance from the IAN to the mandibular first, second and third molars was
smaller in patients younger than 35 years when
compared with older age groups. Adigüzel et al.

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Proximity of mandibular first and second molars to IAC

No.

1

Author

Country

Hiremath et al.6

India

Imaging modality

3-D (CS 9300, Kodak CBCT)

Method

CBCT scans of 40 men
and 40 women

Result
(distance in mm)
Distance from IAN
to mesial apex of 1st molar:
1.46–3.23 mm (men);
0.93–8.03 mm (women)
Average distance for 2nd molar:
1.31–14.7 mm (men);
0.00–6.91 mm (women)

2

3

4

5

6

7

Kawashima et al.1

Chong et al.2

Bürklein et al.7

Tilotta-Yasukawa et al.

8

Adigüzel et al.

68 men, 87 women aged
20 years and older

See Table 1 in study

U.K.

3-D (PaX-Reve3D, VATECH,
Ewoo Technology) operating at
3.5 mA and 85 kV; ﬁeld of view
for mandibular molar region
was 5 × 9 × 5 cm and voxel size
was 0.08 mm.

272 mandibular 2nd molar roots
evaluated from 134 CBCT
scans

Distance between anatomical
apex and IAN was < 3 mm

3-D (Planmeca ProMax 3D,
Planmeca)

627 CBCT scans of a German
population (58.2% women,
41.8% men);
mean age of 51 years

Distance from IAN/IAC
to 1st molar was 4.9 mm,
to 2nd molar was 3.1 mm and
to 3rd molar was 2.6 mm

2-D

2-D radiographic study
of 35 out of 40 cases

Distance of 2nd and 3rd molars
from mandibular canal
was < 1 mm

CBCT scans of hemimandibles

Horizontal distance at level of
apex and IAC area at 2nd molar:
4 mm; greater than that
of 1st molar

3-D (i-CAT Next Generation,
Imaging Sciences International)

CBCT scans of 100 male
and female patients aged
15–65 years

Distance from IAN to 1st molar:
men: 5.1 mm (mesial),
4.8 mm (distal);
women: 4.4 mm (mesial),
approx. 4.1 mm (distal)

See Table 1 in study

Germany

10

Al-Jandan et al.14

U.S.

3-D (i-CAT, Imaging Sciences
International) at 120 kVp and
4–7 mA with 14-bit gray scale
resolution and voxel size of
0.125–0.300 mm

France

Saudi Arabia

Turkey

3-D

8

Simonton et al.9

U.S.

3-D (Accuitomo 3DX Morita
CBCT, J. Morita)

200 patients
(1) Known age: 30–69 years;
(2) Known sex: 25 men and 25
women were collected for each
10-year age bin
(3) CBCT scans covered
mandibular
st
1 molar and IAN

9

Littner et al.11

Israel

2-D

2-D radiographic study of
46 dry mandibles

Mandibular canal was located
3.5–5.4 mm below apices
of both 1st and 2nd molars

10

Chrcanovic et al.13

Sweden

3-D

CBCT scans of 118 subjects

1st and 2nd molar distance
was < 6 mm

52 Volume 3 | Issue 4/2017

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Proximity of mandibular first and second molars to IAC

Fig. 3

Table 1
Summary of the articles that
were included in the review.
Fig. 3
Forest plot for the comparison
of the distance of the inferior
alveolar canal from the apices
of ﬁrst molars in men.

Fig. 4

Fig. 4
Forest plot for the comparison
of the distance from the apices
of ﬁrst molars in women.
Fig. 5

Fig. 5
Forest plot for the comparison
of the distance of the inferior
alveolar canal from the apices
of left ﬁrst molars in men and
women.
Fig. 6

Fig. 6
Forest plot for the comparison
of the distance of the inferior
alveolar canal from the apices
of right ﬁrst molars in men
and women.
Fig. 7

Fig. 7
Forest plot for the comparison
of the distance of the inferior
alveolar canal from the apices
of second molars in men.
Fig. 8
Forest plot for the comparison
of the distance of the inferior
alveolar canal from the apices
of second molars in women.

Fig. 8

Fig. 9
Forest plot for right and left
side.

Fig. 9

Fig. 10
Forest plot for second molar
distal root.
Fig. 11
Forest plot for comparison of
differences in the distance of
the inferior alveolar canal
from second molars in relation
to sex.

Fig. 10

Fig. 11

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Proximity of mandibular first and second molars to IAC

Fig. 12
Schematic representation of
differences in distance
estimated with the respective
2-D and 3-D imaging modality.

Fig. 12

Table 2
Overview of the distance
between the apices of
mandibular ﬁrst and second
molars (data considered for
meta-analysis).

concluded that the distance was smaller in the
groups aged 16–25 years and 56–65 years compared with other age groups.8 Previous studies
have conﬁrmed that the distance between the
apices and the mandibular canal increased with
eruption of mandibular teeth.11 Kawashima et al.
showed that there was increased bone growth
after eruption of teeth and/or inferior migration
of the IAC with age in both sexes.1
Race

Levine studied an American population and
found that white patients on average had a
lower distance between the buccal aspect of
the canal and the outer buccal and superior cortical plates of the mandible.12 They concluded
that, in order to minimize the risk of IAN injury,
these variables should be considered when planning mandibular osteotomies or using monocortical plates.
Hiremath et al. found that the distance from
the IAN to the apices of ﬁrst and second molars
ranged from 0.00 to 14.71 mm in general, 6 and
Adigüzel et al. found it to be 4.1 –5 .1 mm. 8
Chrcanovic found the distance from the IAN to
ﬁrst and second molars to be less than 6 mm.13
Bürklein et al. showed that the distance from
the IAN to ﬁrst molars to be 4.9 mm, to second
molars to be 3.1 mm and to third molars to be
2 .6 mm.7 Chong et al. demonstrated that the
distance between the anatomical apex and the
IAN was less than 3 mm. 2 Al-Jandan et al.
54 Volume 3 | Issue 4/2017

showed that the horizontal distance at the level
of the apex and the IAC area at the second molar
was 4 mm greater than at the ﬁrst molar.14 Alves
et al. found that the distance of second and third
molars from the mandibular canal was less than
1 mm.15 Littner et al. suggested that the mandibular canal was located 3.5–5.4 mm.11 Denio
et al.’s study of dry mandibles concluded that
the distance from second molars to the IAN was
3.7 mm and from ﬁrst molars was 6.9 mm on
2-D radiographs. 8, 16–18
Basically, there are three important processes that inﬂuence the development of the
craniofacial bones: size increase, remodeling and
displacement. The ﬁrst two processes occur
simultaneously by a combination of bone
resorption and displacement. The last one
results in the displacement of all the bones away
from each other to undergo a size increase. The
remodeling and displacement processes change
and vary according to age, sex and race. These
changes will have impact on the location of the
IAC/IAN with respect to the apices of mandibular ﬁrst and second molars.
Quality of evidence

The data in the ﬁrst instance were derived from
secondary data and the studies used varying
methodologies to estimate the distance from
the apices of the mandibular ﬁrst and second
molars to the IAC. Hence, the results obtained
should be interpreted with caution.

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Table 2

Type of tooth

Study

Variables
Left side

Right side

Left side
Bürklein et al.7
Right side
Male
Female
Left side

First molar

Right side
–
Left side
Hiremath et al.6
Right side
Mesial
Adigüzel et al.8
Distal
Male
9

Simonton et al.

Female
Left side
Mesial
Right side
Mesial
Left side
Distal

Bürklein et al.7

Right side

Mesial

Distal
Second molar
Total
Male
Female
Male
Female
Kawashima et al.1

Male
Female
Mesial

Chong et al.2
Distal
Male
Hiremath et al.6
Female

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Mesial
Male
Female
Mesial
Male
Female
Distal
Male
Female
Distal
Male
Female
–
–
Male
Female
Male
Female
–
Male
Female
Male
Female
Male
Female
Male
Female
Mesial
Distal
Mesial
Distal
Mesial
Male
Female
Mesial
Male
Female
Distal
Male
Female
Distal
Male
Female
–
Male
Female
–
Male
Female
–
–
–
–
–
Right side
Left side
Right side
Left side
Right side
Left side
Right side
Left side
Left side
Right side
Left side
Right side

Sample size (n)

Mean ± SD

298
138
160
299
132
167
298
138
160
299
132
167
270
327
138
160
132
167
597
40
40
40
40
317
317
317
317
100
100
100
100
218
79
139
290
109
181
218
79
139
290
109
181
508
188
320
508
188
320
508
188
320
68
87
68
68
87
87
49
57
59
61
40
40
40
40

5.1 ± 2.5
5.8 ± 2.4
4.5 ± 2.4
5.1 ± 2.5
5.7 ± 2.7
4.6 ± 2.2
4.6 ± 2.4
5.3 ± 2.4
4.0 ± 2.2
4.6 ± 2.4
5.2 ± 2.7
4.1 ± 2.1
5.6 ± 2.4
4.3 ± 2.3
5.3 ± 2.4
4.0 ± 2.2
5.2 ± 2.7
4.1 ± 2.1
4.85 ± 2.5
5.82 ± 3.26
3.82 ± 2.22
6.20 ± 2.89
4.36 ± 1.82
5.1 ± 1.6
4.4 ± 1.3
4. ± 1.5
4.1 ± 1.2
6.2 ± 2.6
5.8 ± 2.5
4.9 ± 2.2
4.7 ± 2.2
3.5 ± 2.3
4.1 ± 2.3
3.1 ± 2.3
3.4 ± 2.3
3.9 ± 2.6
2.9 ± 2.0
2.7 ± 2.2
3.7 ± 2.2
2.7 ± 2.2
2.9 ± 2.3
3.5 ± 2.6
2.5 ± 1.9
3.4 ± 2.3
4.0 ± 2.4
3.0 ± 2.2
2.8 ± 2.3
3.6 ± 2.4
2.6 ± 2.1
3.13 ± 2.3
3.8 ± 2.3
2.8 ± 2.1
3.21 ± 2.61
2.51 ± 2.51
3.16 ± 2.56
3.02 ± 2.66
2.62 ± 2.65
2.41 ± 2.36
3.25 ± 1.88
2.59 ± 1.38
2.73 ± 1.77
2.49 ± 1.47
5.01 ± 3.37
5.49 ± 3.07
3.03 ± 1.66
3.7 ± 1.51

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Proximity of mandibular first and second molars to IAC

Conclusion

Agreements and disagreements
between studies included in the review

We can conclude that the average mean distance
between the IAC and the apices of mandibular
molars is approximately 7.3 mm. In addition to
this, certain factors, such as age, sex, race, position of tooth and bone thickness, play a key role
in determining the distance between the IAC and
the apex. The values found are mean values and
the clinical decision should be made on a caseby-case basis and the type of imaging modality
used. There is signiﬁcant application of CBCT in
clinical outcome while treatment planning in the
ﬁrst and second mandibular molar region.

Adigüzel et al. and Simonton et al. used a similar
methodology in determining the distance
between the apices of mandibular first and
second molars and the IAC.8, 9 These two studies
used sagittal scans and intervariability tests and
considered various factors that inﬂuence IAC
location with respect to ﬁrst and second molars.
Bürklein et al. stated the inclusion and exclusion
criteria.7 The above-mentioned studies lack a
scientiﬁc approach in determining the distance
and hence, this might be a source of potential
bias. Chong et al. tried to follow the principle of
the Pythagoras theorem to determine the disAcknowledgment
tance, which is the scientiﬁc method of determining the distance between two points.2 The We would like to thank Drs. Namitha Thomas,
investigators should have considered an inter- Natasha Shetty and Neethu for their initial partiobserver reliability between two dental radiolo- cipation in the review.
gists. The study should also have considered sex
Competing interests
and age as factors in determining the distance.

The authors declare that they have no conﬂict
of interest regarding the materials used in the
present study. No funding was given to conduct
this review.

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BUENOS AIRES 2018

Buenos Aires

World Dental Congress

Argentina

5-8 September 2018
A PASSION

MIT
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C
FOR MANY, A

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ME

30 March 2018

1 June 2018

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DEADLINE

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[58] =>

Interview

Bringing science to the surface
An interview with Prof. Matthias Karl

Prof. Matthias Karl
of Saarland University
in Germany
answers questions on the
signiﬁcance of a newly
published meta-analysis
evaluating Nobel Biocare’s
TiUnite implant surface1
for researchers, clinicians
and patients.

Prof. Karl, what was your rationale for con- What did you set out to discover in all this data?
ducting a meta-analysis to investigate the
clinical performance of implants with the We did not have any predetermined expectaTiUnite surface?
tions—that is another strong point of this review
in my opinion. Our aim was not to cherry-pick
The TiUnite surface was launched over 15 years data, but to conduct an unbiased review of the
ago and in that time certainly has set the stan- literature.
dard in implant dentistry. It’s one of the major
implant surfaces on the market. We felt that it Another unique feature of the study is that we
was time to evaluate TiUnite implants in a com- used implant placement as a baseline. Bone
prehensive meta-analysis of prospective clinical remodeling takes place predominantly between
studies—not with preclinical data, not with ret- implant placement and abutment connection.
rospective data, not with case reports, but the In many studies, it’s only at the prosthetic reshighest possible quality of evidence.
toration that the clock starts to run, but by then
a certain amount of remodeling has already
How did you decide which studies to include in taken place. It’s more honest to go back and
the analysis?
report the implant surgery as the baseline and
assess the bone levels from then on.
We had strict inclusion criteria. We looked only We were able to really look at marginal bone
at prospective clinical studies with at least 20 level changes from the beginning, from the surpatients who had received TiUnite implants at gery, for many, many studies, and also looked
the beginning of the study. A minimum of a into biological complications if they had been
1-year postloading follow-up was also required. reported. Of course, we also looked at periimIn terms of reporting, we had to be able to either plantitis and periimplant pathology.
derive the cumulative survival rate from the
paper or calculate the survival rate based on the The deﬁnition of “periimplantitis” is presently
data given in the paper.
a much-debated topic in dental implantology.
How did you deﬁne it for the purposes of this
Despite the strict inclusion criteria, the study is paper?
thought to be the largest analysis of this kind
on a single brand of implants. What was the The deﬁnition of “periimplantitis” is indeed a hot
scale of the data examined?
topic right now. What we did in the paper is not
to over- or underestimate periimplantitis. If the
It’s certainly the largest such study I’ve seen. primary author referred to “periimplantitis” or if
We reviewed 106 well-documented prospective there was periimplant inﬂammation or periimclinical studies. To have such a high number of plant pathology, we counted this as periimplanprimary studies in a single review is something titis no matter what. We are well aware that
really unique. In total, over 12 ,000 TiUnite these authors were acting on different scales,
implants were part of the evaluation. This rep- but if they used the term “periimplantitis” or
resents a huge database and should be regarded similar, we did not question it.
as a real strength for Nobel Biocare, as well as
the clinicians using Nobel Biocare implants and What were the key ﬁndings of your analysis?
their patients. I think it’s really the highest level
of evidence we have right now documenting the For me, the key ﬁnding was that TiUnite is a
clinical success of a single implant surface.
highly reliable implant surface even in very
58 Volume 3 | Issue 4/2017

Journal of
Oral Science & Rehabilitation

[59] =>

Interview

challenging situations. Nobel Biocare has a full
range of implant designs with the TiUnite surface, and we could not differentiate implant
performance between different implant geometries. In the end, the study results demonstrated that it’s a really great surface. It keeps
the implant in place, and the longevity is proven.
The prevalence of periimplantitis was extremely
low. There were no major biological complications and the marginal bone level changes were
well within the accepted thresholds for a successful implant.
How can the ﬁndings of your analysis now be
used to optimize clinical practice?
Clinicians can use the values presented in the
paper as a reference. This is the real beneﬁt of
such an extensive review. In our own practices,
we can only see a limited number of patients.
What we have here is an analysis of over 12,000
implants spanning a 15 -year period. I would
advise clinicians to look at these values and compare them with what they have seen in their
practices. Then they can ask themselves where
they are in relation to the data and why that
might be. If they are not seeing the same success, why is that? The ﬁndings are a helpful
benchmark for modern practice.

Reference
1.
Karl M, Albrektsson T. Clinical performance of dental implants with a
moderately rough (TiUnite) surface:
a meta-analysis of prospective
clinical studies.
→ Int J Oral Maxillofac Implants.
2017 Jul–Aug;32(4):717–34.
Image: © Schüpbach Ltd.

For more information about the TiUnite
surface and its supporting clinical evidence,
visit nobelbiocare.com/tiunite.
Journal of
Oral Science & Rehabilitation

Volume 3 | Issue 4/2017 59

[60] =>

Guidelines for authors

Authors must adhere
to the following guidelines
Informed consent

It is preferred that there be no more than six authors.
If more authors have participated in the study, the
Patients have a right to privacy that should not be violated without informed consent. contribution of each author must be disclosed at the
Identifying information, including patients’ names, initials or hospital numbers, should end of the document.
not be provided in the manuscript or visual material unless the information is essential
Title
for scientiﬁc purposes and the patient (or parent or guardian) has given written informed
consent for publication. Informed consent for this purpose requires that an identifiable
patient be shown the manuscript to be published. Authors should disclose to these The title should not exceed 35 characters. Capitalize
patients whether any potential identifiable material might be available via the Internet only the ﬁrst word and proper nouns in the title. Please
as well as in print after publication. Nonessential identifying details should be omitted. include a running title as well.
Informed consent should be obtained if there is any doubt that anonymity can be mainAuthor information
tained. For example, masking the eye region in photographs of patients is inadequate
protection of anonymity. If identifying characteristics are altered to protect anonymity,
authors should provide assurance that alterations do not distort scientiﬁc meaning. The following information must be included for each
When informed consent has been obtained, it should be indicated in the manuscript. author:
– Full author name(s)
– Full afﬁliation (department, faculty, institution,
town, country).

Human and animal rights
When reporting experiments on human subjects, authors should indicate whether the
procedures followed were in accordance with the ethical standards of the responsible
committee on human experimentation (institutional and national) and with the Declaration of Helsinki of 1975, as revised in 2013 (www.wma.net/en/30publications/ 10policies/b3/index.html). If doubt exists whether the research was conducted in accordance
with the Declaration of Helsinki, the authors must explain the rationale for their approach, and demonstrate that the institutional review body explicitly approved the
doubtful aspects of the study. When reporting experiments on animals, authors should
indicate whether institutional and national standards for the care and use of laboratory
animals were followed. Further guidance on animal research ethics is available from the
International Association of Veterinary Editors’ Consensus Author Guidelines on Animal
Ethics and Welfare (www.veteditors.org/consensus-author-guidelines-onanimalethics-and-welfare-for-editors).

For the corresponding author, the following information should be included in addition:
– Full mailing address
– Email address.
Abstract and keywords

The manuscript must contain an abstract and a minimum of 3, maximum of 6 keywords. The abstract
should be self-contained, not cite any other work and
not exceed 250 words. It should be structured into the
following separate sections: objective, materials and
methods, results, conclusion and keywords. For case
reports, the sections should be background, case
presentation, conclusion and keywords.
Structure of the main text

Preparing the manuscript text

The body of the manuscript must be structured
as follows:

– Introduction (no subheadings)
– Materials and methods
– Results
The manuscript must be written in U.S. English. The – Discussion
main body of the text, excluding the title page, ab- – Conclusion
stract and list of captions, but including the references, may be a maximum of 4,000 words. ExcepCompeting interests
tions may be allowed with prior approval from the
publisher.
Authors are required to declare any competing ﬁnancial
or other interests regarding the article submitted. Such
Authors will have the opportunity to add more infor- competing interests are to be stated at the end of manmation regarding their article, as well as post videos, uscript before the references. If no competing interests
present a webinar and blog on the DT Science web- are declared, the following will be stated: “The authors
site.
declare that they have no competing interests.”
General

60 Volume 3 | Issue 4/2017

Journal of
Oral Science & Rehabilitation

[61] =>

Guidelines for authors

gether, then use lowercase letters to designate these
in a group (e.g., “Figs. 2a–c”).

Acknowledgments

Acknowledgments (if any) should be brief and included at the end of the manuscript before the refer- Place the references to the images in your article
wherever they are appropriate, whether in the midences, and may include supporting grants.
dle or at the end of a sentence. Provide a caption for
each image at the end of your article.
References
Authors are responsible for ensuring that the information for each reference is complete and accurate.
All references must be cited within the manuscript.
References appearing in the list but not in the manuscript will be removed. In-text citation should follow
the citation–sequence format (e.g., “as discussed by
Haywood et al.15”) using superscript numbers placed
after the punctuation in the relevant sentence. The
references must be numbered consecutively.

Requirements for tables

Each table should be supplied separately and in Microsoft Word format. Tables may not be embedded as
images and no shading or color is to be used.

Tables should be cited consecutively in the manuscript. Place the references to the tables in your article
wherever they are appropriate, whether in the middle
or at the end of a sentence. Every table must have a
The reference list must be numbered and the refer- descriptive caption, and if numerical measurements
ences provided in order of appearance. For the refer- are given the units should be included in the column
ence list, the journal follows the citation style stipu- headings.
lated in Citing medicine: the NLM style guide for auSupplements/supporting material
thors, editors, and publishers. The guidelines may be
viewed and downloaded free of charge at
DT Science allows an unlimited amount of supporting material (such as datasets, videos or other addiwww.ncbi.nlm.nih.gov/books/NBK7256/
tional information) to be uploaded. This material
The reference list may not exceed 50 references.
should be presented succinctly (in English). The author bears full responsibility for the content. Color,
List of captions
animated multimedia presentations, videos and so
Please provide the captions for all visual material at on are welcome and published at no additional cost
to the author or reader. Please refer briefly to such
the end of the manuscript.
material in the manuscript where appropriate (e.g.,
as an endnote).
Abbreviations
Abbreviations should be used sparingly and deﬁned
when ﬁrst used. The abstract and the main manuscript text should be regarded as separate documents
in this regard.
Typography

– Use Times New Roman regular with a font size of 12 pt.
– Use double line spacing with blank lines separating sections and paragraphs.
– Type the text unjustiﬁed and do not apply
hyphenation at line breaks.
– Number all of the pages.
– Use endnotes if necessary, but not footnotes.
– Greek and other special characters may be
included.

Submit your research and
clinical articles to
Dr. Daniele Botticelli at
daniele.botticelli@gmail.com

For all other requests,
contact

Preparing the visual material
Requirements for images

Each image should be supplied separately and the
following formats are accepted: PSD, TIFF, GIF and
JPEG. The image must have a resolution of 300 dpi
and must be no smaller than 6 cm × 6 cm.
Please number the images consecutively throughout
the article by using a new number for each image. If
it is imperative that certain images be grouped to-

Journal of
Oral Science & Rehabilitation

Nathalie Schüller at
n.schueller@dental-tribune.com
T +49 341 4847 4136
Dental Tribune International Publishing Group
Holbeinstr. 29
04229 Leipzig
Germany
www.dtscience.com
www.dental-tribune.com

Volume 3 | Issue 4/2017

61

[62] =>

Imprint: About the publisher

Publishing team

Editorial board

Publisher/President/CEO

Editor-in-Chief

Torsten R. Oemus
t.oemus@dental-tribune.com

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62 Volume 3 | Issue 4/2017

Journal of
Oral Science & Rehabilitation

Daniele Botticelli, Rimini, Italy
Luigi Canullo, Rome, Italy
Torsten R. Oemus, Leipzig, Germany
Board of reviewers
Marcus Abboud, Stony Brook, N.Y., U.S.
Marco Álvarez, Mexico City, Mexico
Conrado Aparicio, Minneapolis, Minn., U.S.
Shunsuke Baba, Osaka, Japan
Franco Bengazi, Brescia, Italy
Andrea Edoardo Bianchi, Milan, Italy
Manuel Bravo Pérez, Granada, Spain
Eriberto Bressan, Padua, Italy
Marco Caneva, Trieste, Italy
Juan Carlos De Vicente Rodríguez, Oviedo, Spain
Stefan Fickl, Würzburg, Germany
Joseph Fiorellini, Philadelphia, Pa., U.S.
Carlo Fornaini, Fiorenzuola d'Arda, Italy
Abel García García, Santiago de Compostela, Spain
Gerardo Gómez Moreno, Granada, Spain
Federico Hernández Alfaro, Barcelona, Spain
Carlos Larrucea Verdugo, Talca, Chile
Baek-Soo Lee, Seoul, South Korea
Dehua Li, Xi’an, China
Francesco Guido Mangano, Milan, Italy
Aleksa Markovic, Belgrade, Serbia
José Eduardo Maté Sánchez de Val, Murcia, Spain
Silvio Meloni, Sassari, Italy
Eitan Mijiritsky, Tel Aviv, Israel
Alberto Monje, Ann Arbor, Mich., U.S.
Yasushi Nakajima, Osaka, Japan
Ulf Nannmark, Gothenburg, Sweden
Wilson Roberto Poi, Araçatuba, Brazil
Rosario Prisco, Foggia, Italy
Alessandro Quaranta, Dunedin, New Zealand
Maria Piedad Ramírez Fernández, Murcia, Spain
Idelmo Rangel García, Araçatuba, Brazil
Fabio Rossi, Bologna, Italy
Hector Sarmiento, Philadelphia, Pa., U.S.
Nikola Saulacic, Bern, Switzerland
Alessandro Scala, Pesaro, Italy
Carlos Alberto Serrano Méndez, Bogotá, Colombia
Andrew Tawse-Smith, Dunedin, New Zealand
Cemal Ucer, Manchester, U.K.
Joaquín Urbizo Velez, La Habana, Cuba

[63] =>

[64] =>

5GVVKPIVJGUEKGPVKƂE
standard. Again.
The evidence points to TiUnite®
The largest meta-analysis of a single implant brand unequivocally shows that
the TiUnite implant surface supports peri-implant health, bone maintenance and
overall treatment success, long term.1
TiUnite is proven to perform – is your implant surface?
Largest meta-analysis of a single implant brand

106

4,694

12,803

prospective
studies

patients

TiUnite
implants

=
*KIJGUVNGXGNGXKFGPEGEQPƂTOUENKPKECNUWEEGUU

95.1%

1.36 %

– 0.9 mm

10-year survival rate
at implant level 1

Prevalence of
peri-implantitis 1, 2

5-year bone level change
at implant level 1

1 Karl, M. and Albrektsson, T. Clinical performance of dental implants with a moderately rough (TiUnite) surface: a
meta-analysis of prospective clinical studies. Int J Oral Maxillofac Implants. 2017;32(4):717-734.
2 Of 106 studies, 47 reported biological complications. Of these 47 papers, 19 reported cases of peri-implantitis in 5.2 %
of patients (64/1229). The authors postulated that, if peri-implantitis did not occur in studies where it was not explicitly
reported, its prevalence would be 1.36 %.
Details of regression analysis can be found in the full publication.

Visit nobelbiocare.com/tiunite
GMT 52723 © Nobel Biocare Services AG, 2017. All rights reserved. Distributed by: Nobel Biocare. Nobel Biocare, the Nobel Biocare logotype and
all other trademarks are, if nothing else is stated or is evident from the context in a certain case, trademarks of Nobel Biocare. Please refer to
nobelbiocare.com/trademarks for more information. Product images are not necessarily to scale. Disclaimer: Some products may not be regulatory
ENGCTGFTGNGCUGFHQTUCNGKPCNNOCTMGVU2NGCUGEQPVCEVVJGNQECN0QDGN$KQECTGUCNGUQHƂEGHQTEWTTGPVRTQFWEVCUUQTVOGPVCPFCXCKNCDKNKV[
For prescription use only. Caution: Federal (United States) law restricts this device to sale by or on the order of a licensed dentist. See Instructions
for Use for full prescribing information, including indications, contraindications, warnings and precautions.

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Table of contents

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