Journal of Oral Science & Rehabilitation No. 3, 2016

Journal of Oral Science & Rehabilitation No. 3, 2016

Cover / Editorial / Contents / About the Journal of Oral Science & Rehabilitation / Benefits of publishing in the journal for authors / Minimally invasive hydraulic elevation of the Schneiderian membrane and insertion of bone graft material using a novel self-tapping implant system: Radiographic and prosthetic aspects / Impact of argon plasma treatment on microbiological surface receptivity of titanium implants: An in vitro study / Comparison of hard- and softtissue changes using a superimposition technique: A prospective case series study / Influence of fatigue on resistance and deformation of implant abutments used for provisional prosthetic restoration / Human pulps capped with PDGF: A pilot study / Importance of the axial reference plane in computed tomography for dental implant surgery: A cadaveric study / Immediate loading of variable-thread expanding tapered-body implants placed into maxillary post-extraction or healed sites using a guided surgery approach: An up-to-five-year retrospective analysis / An in vitro study on viscosity using an electromagnetically spinning sphere viscometer / Authors must adhere to the following guidelines / Imprint / Subscription form

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Journal of

Oral Science
&
Rehabilitation
Volume 2 — Issue 3/2016

ISSN 2365-6891

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

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[3] => JOSR_A4_Editorial_03.qxp_Layout 1

Editorial

Journal of

Oral Science
&
Rehabilitation
What is the most severe
early complication concerning dental implants?

The placement of dental implants, although not without early
complications—which are usually self-limited—has become a
scheduled, routine and standardized surgical procedure. However,
it is important that education in oral implantology adequately
cover the immediate bleeding complications, especially in the floor
of the mouth, that may arise and that, although infrequent, may be
severe, sometimes even life-threatening, and require hospitalization for emergency treatment.
The interforaminal area in the mandible is quite often considered
as the easiest region in which to insert dental implants, such as
placing two implants to support an overdenture. However, the
most serious bleeding accidents occur in this region owing to injury
of the terminal branches of the sublingual or submental arteries if
the lingual cortical plate is perforated during drilling or implant
placement. This vascular injury can trigger massive internal bleeding in the mouth floor, which expands, causing protrusion and displacement of the tongue and sometimes subsequent obstruction
of the airways, which may necessitate an emergency tracheotomy
or even be fatal. Thus, the clinician should not treat placement of
anterior mandibular implants lightly in the belief that placement in
this region is easy.
In order to minimize the possibility of perforating the lingual cortical plate, some authors recommend placing implants that are not
very long (10–12 mm) in the anterior region of the mandible. Tilting
implants in a buccolingual direction, tipping the implant apex
toward the vestibule, is another option. Perhaps the most important
factor concerning minimization of the risk of these complications
is that the surgeon carrying out the implant therapy should have
extensive anatomical knowledge of this area, including the important anatomical structures located in the sublingual space.
Dr. Miguel Peñarrocha Diago
Co-Editor
Journal of
Oral Science & Rehabilitation

Volume 2 | Issue 3/2016

03

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Contents

03
Editorial
Dr. Miguel Peñarrocha Diago
06
About the Journal of Oral Science & Rehabilitation
08
Marco Tallarico et al.
Minimally invasive hydraulic elevation of the Schneiderian membrane and
insertion of bone graft material using a novel self-tapping implant system:
Radiographic and prosthetic aspects
16
Marco Annunziata et al.
Impact of argon plasma treatment on microbiological surface receptivity of
titanium implants: An in vitro study
20
Erta Xhanari and Milena Pisano
Comparison of hard- and soft-tissue changes using a superimposition
technique: A prospective case series study
26
Rubén Agustín Panadero et al.
Inﬂuence of fatique on resistance and deformation of implant abutments
used for provisional prosthetic restoration
34
Gaia Pellegrini et al.
Human pulps capped with PDGF: A pilot study
42
Fabio Camacho Alonso et al.
Importance of the axial reference plane in computed tomography for dental
implant surgery: A cadaveric study
50
Giovanni Polizzi et al.
Immediate loading of variable-thread expanding tapered-body implants
placed into maxillary post-extraction or healed sites using a guided surgery
approach: An up-to-5 year restrospective analysis
62
Atsuko Imai et al.
An in vitro study on viscosity using an electromagnetically spinning sphere
viscometer
68
Guidelines for authors
70
Imprint — about the publisher

04 Volume 2 | Issue 3/2016

Journal of
Oral Science & Rehabilitation

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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 2 | Issue 3/2016

Journal of
Oral Science & Rehabilitation

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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
increased impact of their research through open-access publishing on
www.dtscience.com.
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www.dtscience.com and www.dental-tribune.com.
– Authors can also post videos relating to their research, present
a webinar and blog on www.dtscience.com.

Subscription price
€50.00 per issue, including VAT and shipping costs.

Information for subscribers
The journal is published quarterly. Each issue is published as both a print
version and an e-paper on www.dtscience.com.

Terms of delivery
The subscription price includes delivery of print journals to the recipient’s
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Copyright © 2016 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
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Minimally invasive sinus lift implant system

Minimally invasive hydraulic elevation
of the Schneiderian membrane and
insertion of bone graft material using
a novel self-tapping implant system:
Radiographic and prosthetic aspects

Abstract
Objective
Marco Tallarico,a, b Erta Xhanari,c Paolo Pagliad & Silvio
Mario Melonib
a

Private practice, Rome, Italy
Dentistry Unit, University Hospital of Sassari,
Sassari, Italy
c
Private practice, Tirana, Albania
d
Private dental laboratory, Rome, Italy

The objective of this article was to report the clinical and radiographic
performance of a novel implant system that allows for hydraulic Schneiderian membrane elevation and simultaneous bone graft augmentation.

Corresponding author:
Dr. Marco Tallarico
Via di Val Tellina 116
00151 Rome
Italy

Case description

A 63-year-old female patient presenting with compromised ﬁxed dental
prostheses supported by failing teeth in her posterior maxilla underwent
transcrestal sinus ﬂoor elevation using a novel implant system. Implant
failure, any complications and bone gain measured using cone beam computed tomography (CBCT) were assessed.
Results

T +39 328 075 8769
me@studiomarcotallarico.it
How to cite this article:
Tallarico M, Xhanari E, Paglia P, Meloni SM. Minimally invasive hydraulic elevation of the Schneiderian membrane and
insertion of bone graft material using a novel self-tapping
implant system: radiographic and prosthetic aspects.
J Oral Science Rehabilitation.
2016 Sep;2(3):8–14.

The residual alveolar ridge height was 3.2 mm. A 14.5 mm length implant
was placed and followed for 20 months. Bone gain was 18.5 mm after a
healing period of eight months. One year after implant loading, CBCT scans
showed the stability of the grafted material.
Conclusion

Hydraulic elevation of the Schneiderian membrane using the iRaise sinus
lift system (Maxillent, Herzliya, Israel) can be considered a valuable treatment option for the rehabilitation of atrophic edentulous posterior maxillae.
Keywords

Dental implant, sinus lift, Schneiderian membrane, atrophic maxilla, bone
augmentation.
08 Volume 2 | Issue 3/2016

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Minimally invasive sinus lift implant system

Figs. 1 & 2

Introduction

Case presentation

In the posterior sextants of the maxilla, tooth loss
is generally associated with alveolar bone loss
and sinus pneumatization.1 In addition, poor bone
quality may have a negative inﬂuence on the survival rate of implants.2 There is no consensus on
treatment for the atrophic posterior maxilla, with
the dilemma of whether to place short implants3, 4
or tilted implants5, 6 or to augment the ﬂoor of the
maxillary sinus.7, 8 In a recent review of the literature, Pjetursson et al. reported that the placement of dental implants in combination with
maxillary sinus ﬂoor elevation using a lateral approach is a predictable treatment option showing
high medium-term implant survival rates and low
incidences of complications.7 However, the lateral approach to the sinus entails elevation of a
large mucoperiosteal ﬂap that affects postoperative recovery of the patient and the additional
expense of the augmentation procedure.9 Schneiderian membrane perforations, nose bleeding,
postoperative pain and swelling could be considered major risks.10 The elevation of the maxillary
sinus ﬂoor through the alveolar crest (transalveolar) was ﬁrst described by Tatum11 and modiﬁed
by Summers.12 Subsequently, various modiﬁcations to the original technique have been reported, in order to improve the predictability and
safety, such as the use of atraumatic lifting
drills,13 membrane elevation via inﬂation of a balloon catheter,14 and the use of hydraulic15 or negative pressure.16
The aim of this clinical report was to present
a novel self-tapping endosseous implant system
(iRaise, Maxillent, Herzliya, Israel) developed for
sinus augmentation. The advantage of this system is the ability to perform major sinus lift augmentation via a minimally invasive transcrestal
approach and to simultaneously place an implant, with minimal patient discomfort and shortened treatment time.

A 63-year-old female patient presented with compromised ﬁxed dental prostheses supported by
failing teeth in her posterior maxilla (Figs. 1 & 2).
The patient reported esthetic concerns and impairment of her masticatory function; consequently, she desired replacement of the prostheses. A cone beam computed tomography (CBCT)
scan was performed to evaluate the amount of
residual bone. On the right side, conventional
implant placement was planned. However, on the
left side, the distance from the maxillary crest to
the sinus ﬂoor was 3.2 mm, requiring a bone augmentation procedure. After detailed consultation,
various treatment options were discussed with
the patient. Closed major sinus ﬂoor augmentation with a transcrestal approach using the iRaise
implant system was planned for the maxillary left
ﬁrst molar position to support a screw-retained
ﬁxed dental prosthesis. An adjunctive implant
was planned for the maxillary left ﬁrst premolar
position.
The day before the implant placement, the
patient underwent intranasal spray therapy
(thiamphenicol glycinate acetylcysteinate,
810 mg/4 mL) b.i.d. One hour before surgery, a
single dose of antibiotic (2 g of amoxicillin and
clavulanic acid) was administered prophylactically. A 0.2% chlorhexidine mouthwash was
administered for 1 min prior to the implantation
procedure.
Local anesthesia was administered (articaine
with 1:100,000 epinephrine) and a small
full-thickness mucoperiosteal ﬂap was elevated.
A 2 mm diameter round bur was used to mark
the implant site. The osteotomy was prepared
with a 2 mm twist drill 1 mm below the sinus
ﬂoor. A periapical radiograph with a depth guide
was performed in order to verify the drilling
angle and depth, as well as the distance to the
sinus ﬂoor. The implant recipient site was wide-

Journal of
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Volume 2 | Issue 3/2016 09

Fig. 1
Preoperative panoramic
radiograph.
Fig. 2
Alveolar ridge before implant
placement (occlusal view).

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Minimally invasive sinus lift implant system

Fig. 3

Figs. 3 & 4

Preoperative CBCT scan.
Fig. 4
The iRaise sinus-lift system
(Maxillent, Herzliya, Israel).
Fig. 5
CBCT scan immediately after
implant placement.
Figs. 5 & 6

Fig. 6
CBCT scan six months after
implant placement.

Figs. 7 & 8

Fig. 7
Deﬁnitive prostheses
on the cast (occlusal view).
Fig. 8
Deﬁnitive prostheses
on the cast (frontal view).

ned to allow the placement of a 5 mm diameter
implant, according to the drilling protocol suggested by the manufacturer and reported in a previously published paper.17 The length of the implant was selected beforehand based on the
residual bone height, measured using the preoperative CBCT scan, from the bone crest to the sinus
ﬂoor, along the implant’s planned axis. A 14.50 mm
length implant (iRaise, Maxillent, Herzliya, Israel)
was used according to a residual bone height of
3.21 mm (Fig. 3). The implant was ﬁrst inserted
into the osteotomy until it reached the end of the
prepared site. The implant was then slowly advanced until the sinus ﬂoor was penetrated for
approximately 1 mm. A periapical radiograph was
performed in order to determine whether the implant had penetrated the sinus ﬂoor. A saline syringe with 2–3 cm3 of a 0.9% sterile saline solu10 Volume 2 | Issue 3/2016

tion was connected to the implant through the
tubing port. With this system, the tube connector
is easily assembled on the implant, allowing injection of ﬂuids with a standard Luer lock connector.
Saline solution was gently injected through the
implant and into the sinus and slight bleeding was
noted in the retracted saline solution upon stopping the injection. A syringe containing 2 cm3 of a
ﬂowable bone graft material (MBCP Gel, Biomatlante, Vigneux-de-Bretagne, France) was subsequently connected to the same port. The material
was slowly injected through the implant into the
sinus (Fig. 4). After the grafting procedure had
been completed, the hydraulic system was disconnected from the implant, and the implant was
inserted to its entire length into the osteotomy and
the grafted sinus cavity and left to heal according
to a submerged protocol. An additional implant

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Minimally invasive sinus lift implant system

Figs. 9 & 10

Figs. 11 & 12

was placed after completing the iRaise surgical sequence. A postoperative CBCT scan was taken with
reduced voxel size, ﬁeld of view and milliampere
settings (Fig. 5). After surgery, intranasal spray therapy (thiamphenicol glycinate acetylcysteinate,
810 mg/4 mL) was continued for ten days, an antibiotic (1 g of amoxicillin and clavulanic acid b.i.d.)
for six days and a 0.2% chlorhexidine mouthwash
(1 min b.i.d.) for two weeks. A soft diet was recommended for one week, while 1 g of paracetamol was
prescribed in case of pain. The sutures were removed after one week, and oral hygiene instructions
were emphasized.
Six months after implant placement, a CBCT
scan was taken with the same parameters used for
the postoperative scan, and the healing abutments
were connected. The bone gain was 18.5 mm
(Fig. 6). Deﬁnitive screw-retained metal-free restorations were delivered eight months after implant
placement (Figs. 7–9). The occlusion was carefully
checked. Recall appointments for oral hygiene
maintenance and oral hygiene instructions were set
for every four months after loading. The occlusion
was evaluated at each visit. CBCT scans were performed one year after implant loading (20 months
after implant placement) and compared with the
previously taken CBCT scans (Figs. 10–16).

Discussion

Fig. 9
Metal-free framework.

The present case report is one of the ﬁrst aimed
at evaluating a novel implant system that allows
for minimally invasive major sinus ﬂoor elevation at the time of implant placement. According
to a recent Cochrane systematic review, if the
residual alveolar bone height is 3–6 mm, a transcrestal approach to lifting the Schneiderian
membrane and placing 8 mm implants may lead
to fewer complications than would a lateral window approach and placing implants at least
10 mm long.19
In the case presented, the patient experienced minimal discomfort and was functionally restored in a shorter period than are patients
treated with a two-stage sinus grafting
technique. In investigating the transcrestal osteotome technique for sinus ﬂoor augmentation,
some researchers have recorded high rates of
patient satisfaction.7, 20, 21 Maxillary sinus ﬂoor
elevation with a transcrestal approach is advocated as a minimally invasive procedure,
owing to the minimal surgical ﬂap required.
Moreover, the lateral sinus wall remains intact,
reducing postoperative morbidity.22, 23 This
technique is widely documented in the literature

Journal of
Oral Science & Rehabilitation

Volume 2 | Issue 3/2016 11

Fig. 10
Right lateral view of the
deﬁnitive prosthesis taken
one year after loading.
Fig. 11
Frontal view of the deﬁnitive
prosthesis taken one year
after loading.
Fig. 12
Left lateral view of the
deﬁnitive prosthesis taken
one year after loading.

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Minimally invasive sinus lift implant system

Fig. 13

Figs. 14 & 15

Fig. 13
Panoramic radiograph taken
one year after loading.
Fig. 14
CBCT scan one year after
loading (sagittal view).
Fig. 15
CBCT scan one year after
loading (coronal view).

and supported by several longitudinal studies
that attest to an average implant survival rate
close to 92% in the medium term.7, 8, 24 Recent
publications have shown that transalveolar
sinus ﬂoor elevation is a reliable method for implant placement in the posterior maxilla, even
at sites with ≤ 4 mm of residual alveolar bone
height.17, 25–27 Nevertheless, implant survival
rates may decrease with reduced residual bone
height.18, 28
The main concerns related to the transcrestal
approach, compared with the lateral surgical
approach, are the absence of direct visualization
12 Volume 2 | Issue 3/2016

of the sinus cavity and Schneiderian membrane,
the limited amount of bone augmentation achieved and the high risk of inadvertent perforation
of the Schneiderian membrane during fracture
of the sinus ﬂoor with osteotomes, or burs, with
or without stop drills, without the possibility of
repairing the torn membrane. Nevertheless, in
an eight-year retrospective study on 1,100 participants with 1–5 mm of residual bone height
who received 1,557 implants with minimally
invasive hydraulic elevation of the Schneiderian
membrane, an incidence of membrane perforation of less than 0.5 % was reported.15

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Minimally invasive sinus lift implant system

Fig. 16

Fig. 16
Superimposition of the CBCT
scans taken six months after
implant placement (red) and
one year after loading (gray)
showing stability of the
grafted material over time.

The iRaise implant system is a uniquely designed
implant housing an L-shaped channel separate
from the prosthetic connection and the oral
cavity, thereby eliminating the possibility of bacteria migrating into the bone. Through this channel, saline is introduced to elevate the Schneiderian membrane. The iRaise system allows the
clinician to perform a minimally invasive sinus
augmentation procedure immediately. The hydraulic elevation of the Schneiderian membrane
and the insertion of bone graft material are performed through the implant itself, resulting in
fewer complications, shorter treatment time and
greater comfort for patients, compared with the
open sinus lift procedure.
Closed major sinus ﬂoor augmentation with
a transcrestal approach can be accomplished
using a novel system that allows for hydraulic
elevation of the Schneiderian membrane, injection of a flowable bone graft material and
simultaneous dental implant placement, with
minimal patient discomfort. Long-term clinical
studies on larger cohorts of patients are needed
to conﬁrm these preliminary results.

Competing interests
This was an investigator-initiated trial. The trial
was supported partially by Maxillent.

Acknowledgments
The authors wish to thank Maxillent (Herzliya,
Israel) for its partial support of this trial and
provision of the implants and prosthetic components. The authors also wish to thank the
staff of the dental laboratory (Odontotecnica
Paglia & Moretti, Rome, Italy) who manufactured the deﬁnitive prostheses.

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25.
Ahn SH, Park EJ, Kim ES. Reamer-mediated
transalveolar sinus ﬂoor elevation without
osteotome and simultaneous implant
placement in the maxillary molar area: clinical
outcomes of 391 implants in 380 patients.
→ Clin Oral Implants Res.
2012 Jul;23(7):866–72.

19.
Esposito M, Felice P, Worthington HV.
Interventions for replacing missing teeth:
augmentation procedures of the maxillary
sinus.
→ Cochrane Database Syst Rev.
2014;5:CD008397.

26.
Stavropoulos A, Karring T, Kostopoulos L.
Fully vs. partially rough implants in maxillary
sinus ﬂoor augmentation: a randomized-controlled clinical trial.
→ Clin Oral Implants Res.
2007 Feb;18(1):95–102.

20.
Pjetursson BE, Ignjatovic D, Matuliene G,
Brägger U, Schmidlin K, Lang NP.
Transalveolar maxillary sinus ﬂoor elevation
using osteotomes with or without grafting
material. Part II: radiographic tissue
remodeling.
→ Clin Oral Implants Res.
2009 Jul;20(7):677–83.

27.
Tallarico M, Meloni SM, Xhanari E, Pisano M,
Cochran DL. Minimally Invasive Sinus
Augmentation Procedure
Using a Dedicated Hydraulic Sinus Lift
Implant Device: A Prospective Case Series
Study on Clinical, Radiologic,
and Patient-Centered Outcomes.
→ Int J Periodontics Restorative Dent.
2016. doi:10.11607/prd.2914.

21.
Del Fabbro M, Corbella S, Weinstein T,
Ceresoli V, Taschieri S. Implant survival rates
after osteotome-mediated maxillary sinus
augmentation: a systematic review.
→ Clin Implant Dent Relat Res.
2012 May;14 Suppl 1:e159–68.
22.
Chan HL, Oh TJ, Fu JH, Benavides E,
Avila-Ortiz G, Wang HL. Sinus augmentation
via transcrestal approach: a comparison
between the balloon and osteotome
technique in a cadaver study.
→ Clin Oral Implants Res.
2013 Sep;24(9):985–90.
23.
Bruschi GB, Crespi R, Capparè P, Gherlone E.
Transcrestal sinus ﬂoor elevation: a
retrospective study of 46 patients up to 16
years.
→ Clin Implant Dent Relat Res.
2010 Oct;14(5):759–67.

16.
Suguimoto RM, Trindade IK, Carvalho RM.
The use of negative pressure for the sinus lift
procedure: a technical note.
→ Int J Oral Maxillofac Implants.
2006 May-Jun;21(3):455–8.

14 Volume 2 | Issue 3/2016

24.
Nkenke E, Stelzle F. Clinical outcomes of sinus
ﬂoor augmentation for implant placement
using autogenous bone or bone substitutes: a
systematic review.
→ Clin Oral Implants Res.
2009 Sep;20 Suppl 4:124–33.

Journal of
Oral Science & Rehabilitation

28.
Rosen PS, Summers R, Mellado JR, Salkin LM,
Shanaman RH, Marks MH, Fugazzotto PA.
The bone-added osteotome sinus ﬂoor
elevation technique: multicenter retrospective
report of consecutively treated patients.
→ Int J Oral Maxillofac Implants.
1999 Nov/Dec;14(6):853–8.

[15] => JOSR_A4_Editorial_03.qxp_Layout 1

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[16] => JOSR_A4_Editorial_03.qxp_Layout 1

Argon plasma treatment of titanium implants

Impact of argon plasma
treatment on microbiological
surface receptivity of titanium
implants: An in vitro study

Abstract
Objective
Marco Annunziata,a Pablo Galindo Moreno,b
Giovanna Donnarumma,c Pina Caputo,c
Livia Nastria & Luigi Guidaa
a

Multidisciplinary Department of Medical-Surgical and
Dental Specialties, Second University of Naples,
Naples, Italy
b
Department of Oral Surgery and Implant Dentistry,
School of Dentistry, University of Granada,
Granada, Spain
c
Department of Experimental Medicine, Microbiology
Section, Second University of Naples, Naples, Italy
Corresponding author:
Dr. Marco Annunziata
Multidisciplinary Department of Medical-Surgical and
Dental Specialties, Second University of Naples
Via L. De Crecchio 6
80138 Naples
Italy

Pretreatment of dental implants by argon plasma has been suggested to
increase their surface energy and enhance integration of both hard and
soft periimplant tissue. However, no data are available on the risk of implant sterility loss after this process. This study aimed to test whether the
treatment of implant ﬁxtures by argon plasma in conditions compatible
with clinical use produced an increased risk of microbiological contamination.
Materials and methods

Thirty (15 control and 15 test) sterile Grade 4 titanium implants were used.
Test implants were removed from their original packages, pretreated in
an argon plasma chamber for 12 min, and then immersed in a bacterial
culture medium (Luria-Bertani broth) at 37°C for 72 h. Control implants
were directly transferred to Luria-Bertani broth.
Results

T + 39 081566 5514
marco.annunziata@unina2.it
How to cite this article:
Annunziata M, Galindo Moreno P, Donnarumma G,
Caputo P, Nastri L, Guida L. Impact of argon plasma
treatment on microbiological surface receptivity of titanium
implants: an in vitro study.
J Oral Science Rehabilitation.
2016 Sep;2(3):16–8.

When the culture broths were examined after the 72 h incubation, no
traces of bacterial contamination were found for either controls or test
implants.
Conclusion

Within the limits of this study, the data reported suggest that argon plasma
technology could be used to pretreat implant ﬁxtures immediately before
their surgical placement without increasing the risk of microbiological contamination.
Keywords

Argon plasma, dental implant, microbiological contamination.
16 Volume 2 | Issue 3/2016

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Argon plasma treatment of titanium implants

Introduction
Argon plasma is widely employed as the ﬁnal step
of the manufacturing process of titanium implant
ﬁxtures before their sterilization by gamma rays.
With this treatment, a spray of argon under pressure at room temperature is used to clean implants and remove microbiological and organic
contaminants from the metal surface. At the
same time, however, the atomic bombardment
to which the titanium surface is subjected, causes its activation, that is, a state of excitation of
the electronic mantle and the modiﬁcation of its
physicochemical and biological features.1
The activation obtained during the manufacturing phase is temporary and will have ceased
once the implant ﬁxture is used clinically. It has
been suggested that the reactivation of the titanium surface by argon plasma immediately
before the implant positioning in the oral cavity
could be advantageous in terms of the integration of both hard and soft periimplant tissue.
In vitro and animal studies performed in sterile environments have shown an increased surface energy and an enhanced early biomechanical ﬁxation of dental implants pretreated by
argon plasma.2–4 Furthermore, preliminary results have suggested that treatment of titanium
abutments by argon plasma may enhance cell
adhesion at the early stage of periimplant
soft-tissue healing5 and marginal bone preservation over time.6 However, no data are available about the possible effect of this treatment
on the implant surface receptivity toward environmental bacteria and on the risk of sterility

loss of the ﬁxture just before its surgical placement. The aim of the present study was to test
whether the treatment of implant ﬁxtures by
argon plasma in conditions compatible with clinical use produced an increased risk of microbiological contamination.

Materials and methods
Thirty (15 control and 15 test) sterile Grade 4 titanium implant fixtures with a sandblasted and
acid-etched surface (ZirTi, average surface roughness of 1.3 μm; Sweden & Martina, Due Carrare,
Padua, Italy) were used for this study. Control
implants were directly transferred with sterile
tweezers from their original packaging into test
tubes containing 5 ml of Luria-Bertani broth
(Oxoid, Basingstoke, UK) and incubated at 37 °C
for 72 h. Test implants were inserted into a metallic holder (Fig. 1) and pretreated in an argon plasma chamber (Plasma R, Diener electronic, Ebhausen, Germany) for 12 min at room temperature and
then transferred to culture broth. In order to simulate the clinical practice and environment, the
time between the removal of each ﬁxture from its
sterile package, or from the argon plasma chamber, and its immersion in the culture broth was
standardized at 60 s and the transfer was performed in a nonprotective environment. Three
independent experiments were carried out under
the same conditions.

Fig. 1

Fig. 1

Test implants inserted into
a metallic holder before
pretreatment in the argon
plasma chamber.

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Argon plasma treatment of titanium implants

Fig. 2

Fig. 2
Culture broths examined after
the 72 h incubation. No traces
of bacterial contamination
were found for either controls
or test implants.

Results

Competing interests

When the culture broths were examined after the The authors declare that they have no competing
72 h incubation, no traces of bacterial contamina- interests.
tion were found for either controls or test implants
(Fig. 2).

Conclusion
Within the limits of this study, the data reported
suggest that argon plasma technology could be
used to pretreat implant fixtures immediately
before their surgical placement without increasing the risk of microbiological contamination.
However, additional microbiological and preclinical studies should be performed to test the clinical
applicability of this procedure.

References

1.
Aronsson BO, Lausmaa J, Kasemo B. Glow
discharge plasma treatment for surface
cleaning and modiﬁcation of metallic
biomaterials.
→ J Biomed Mater Res.
1997 Apr;35(1):49–73.

3.
Giro G, Tovar N, Witek L, Marin C, Silva NR,
Bonfante EA, Coelho PG. Osseointegration
assessment of chairside argon-based
nonthermal plasma-treated Ca-P coated
dental implants.
→ J Biomed Mater Res A.
2013 Jan;101A(1):98–103.

2.
Coelho PG, Giro G, Teixeira HS, Marin C, Witek
L, Thompson VP, Tovar N, Silva NR.
Argon-based atmospheric pressure plasma
enhances early bone response to rough
titanium surfaces.
→ J Biomed Mater Res A.
2012 Jul;100A(7):1901–6.

5.
Canullo L, Peñarrocha-Oltra D, Marchionni S,
Bagán L, Peñarrocha-Diago MA, Micarelli C.
Soft tissue cell adhesion to titanium
abutments after different cleaning
procedures: preliminary results of a
randomized clinical trial.
→ Med Oral Patol Oral Cir Bucal.
2014 Mar;19(2):e177–83.

4.
Teixeira HS, Marin C, Witek L, Freitas A Jr,
Silva NR, Lilin T, Tovar N, Janal MN, Coelho
PG. Assessment of a chair-side argon-based
non-thermal plasma treatment on the surface
characteristics and integration of dental
implants with textured surfaces.
→ J Mech Behav Biomed Mater.
2012 May;9:45–9.

18 Volume 2 | Issue 3/2016

Journal of
Oral Science & Rehabilitation

6.
Canullo L, Peñarrocha D, Clementini M,
Iannello G, Micarelli C. Impact of plasma
of argon cleaning treatment on implant
abutments in patients with a history of
periodontal disease and thin biotype:
radiographic results at 24-month follow-up
of a RCT.
→ Clin Oral Implants Res.
2015 Jan;26(1):8–14.

[19] => JOSR_A4_Editorial_03.qxp_Layout 1

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[20] => JOSR_A4_Editorial_03.qxp_Layout 1

Hard- and soft-tissue changes with a superimposition technique

Comparison of hard- and softtissue changes using a
superimposition technique:
A prospective case series study

Abstract
Objective
Erta Xhanaria & Milena Pisanob
a
b

Independent researcher, Tirana, Albania
Independent researcher, Arzachena, Italy

This prospective case series study reports on a novel comprehensive
method using digitized model casts and a superimposition technique to
allow an objective evaluation of the hard- and soft-tissue parameters.
Materials and methods

Corresponding author:

Any patients requiring all-ceramic restoration of the anterior maxillary
teeth were recruited and treated between January 2014 and December
2014. No inclusion or exclusion criteria were considered. Soft-tissue
level changes were measured on the casts taken before and after treatment, using a novel digital technique.

Dr. Erta Xhanari
Sulejman Delvina, 19
1001 Tirana
Albania
info@ertaxhanari.com

Results
How to cite this article:
Xhanari E, Pisano M. Comparison of hard- and soft-tissue
changes using a superimposition technique: a prospective
case series study.
J Oral Science Rehabilitation.
2016 Sep;2(3):20–5.

Eight patients with a total of 34 all-ceramic veneer restorations were
treated. One year after delivery of the deﬁnitive restorations, no complications were observed (fracture, wear, chipping or debonding). Mean
soft-tissue levels improved between bonding and the one-year follow-up
examination. The mean height of the mesial and distal papillary changes
was 0.64 ± 0.31 and 0.47 ± 0.28, respectively.
Conclusion

The technique presented offers an objective evaluation of the hard- and
soft-tissue changes, and it could complement previously established
methods.
Keywords

Esthetic score, porcelain veneer, soft tissue, superimposition, CAD/CAM.
20 Volume 2 | Issue 3/2016

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Hard- and soft-tissue changes with a superimposition technique

Introduction
Esthetic outcomes and patient satisfaction have
become the main focus of interest in esthetically sensitive areas.1, 2 The level and thickness of the
soft tissue, as well as its color and texture, are
decisive for the natural appearance of an
implant-supported restoration.3
Over the last 20 years, the evaluation of the
success of tooth- and implant-supported restorations has shifted from judging only the survival rate of the restoration itself to additionally
assessing whether an esthetic appearance similar to the adjacent teeth has been achieved.
Today, the main concern is whether the surrounding bone architecture and soft-tissue texture and
color can precisely and biomimetically emulate
nature.4 Assessment of esthetically successful
treatment outcomes is validated clinically by
several objective periodontal and esthetic parameters.5–7 However, there is still a lack of clinical
comparative studies in the current literature
regarding objective outcome evaluation from an
esthetic perspective.8–13
In 2004, the International Team for Implantology presented a treatment guide to provide
clinicians with practical and evidence-based
clinical instructions for implant restorations in
the esthetic zone.14 Successful tissue integration
and pleasing esthetic outcomes after the application of this treatment protocol have been reported in retrospective15 and prospective16 case
series studies. Jemt proposed an index, termed
the Papilla Index, to assess the size and volume
of the interproximal papillae adjacent to a
single tooth. The index defines five distinct
levels, ranging from the complete absence of
papillary tissue (index score of 0) to hyperplastic
papillae (index score of 4).17 Meijer et al. published the Implant Crown Aesthetic Index, which
stipulates criteria related to the implant restoration itself and those associated with the surrounding soft tissue.5 Fürhauser et al. proposed
an index, termed the Pink Esthetic Score (PES),
focusing essentially on the soft-tissue aspects
associated with an anterior single implantsupported restoration.6 Seven distinct softtissue parameters are considered: the presence
or absence of mesial and distal papillae, the level
and curvature of the line of emergence of the
implant restoration from the mucosa at the
facial aspect, the facial soft-tissue convexity (in
analogy to a root eminence), and the color and
texture of the facial marginal periimplant

mucosa. Each parameter score can range from
0 to 2, which results in a maximum score of 14.
Finally, Belser et al. proposed a ﬁve-variable index, termed the White Esthetic Score (WES),
focusing on the visible part of the implant restoration itself and usable in combination with the
previously reported PES.15
The aim of this prospective case series study
was to propose a novel comprehensive method
using digitized model casts and a superimposition technique to allow an objective evaluation
of the hard- and soft-tissue parameters for both
tooth- and implant-supported restorations.

Materials and methods
Any patients requiring all-ceramic restoration
of the anterior maxillary teeth were recruited
and treated between January 2014 and December 2014. All of the patients were treated in a
private dental center in Rome, Italy, by the same
clinician (EX). No inclusion or exclusion criteria
were considered. Initial photographs and radiographs were taken (Fig. 1). Diagnostic casts
were obtained from polyvinyl siloxane impressions (Aquasil Putty DECA and Aquasil Ultra LV/
XLV Regular Set, DENTSPLY International, Milford, Del., U.S.) taken with customized lightcuring acrylic impression trays (Elite LC Tray,
Zhermack, Badia Polesine, Italy) fabricated from
preliminary casts. A diagnostic wax-up was
performed (Fig. 2) and used to fabricate a silicone guide. Acrylic duplication of the wax-up
was performed directly in the patient’s mouth,
using the silicone guide (direct mock-up; Fig. 3)
in order to test the function and esthetics of the
envisioned restorations. Dental preparation was
carried out according to a minimally invasive
approach (Fig. 4) based on the silicone guide, to
avoid over-reducing areas of the teeth. A new
cast was obtained for the fabrication of the
all-ceramic veneer restorations. The allceramic veneer restorations were bonded according to a previously published technique.18
One year after delivery of the deﬁnitive restorations (Fig. 5), a new polyvinyl siloxane impression was taken for each patient to allow direct
comparison with the pre-treatment scenario.
Pre- and post-treatment model casts were
poured using a conventional single-pouring
technique. Vacuum-mixed, low-expansion
(0.09%) Type IV dental stone was vibrated into
the impression (CAM-base, Dentona, Dortmund,

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Hard- and soft-tissue changes with a superimposition technique

Figs. 1 & 2

Fig. 1
Preoperative views revealing
worn maxillary anterior teeth.
Fig. 2
Diagnostic wax-up.
Fig. 3
Direct acrylic mock-up.

Figs. 3 & 4

Fig. 4
Minimally invasive tooth
preparation.
Fig. 5
One-year postoperative
intra-oral view.

Fig. 5

Germany). The stone casts were allowed to set
for 2 h before separation from the impressions.
The model casts were then scanned using both
a cone beam computed tomography (CBCT) scanner (CRANEX 3D, SOREDEX, Tuusula, Finland)
with a 1 mm copper ﬁlter and a dental scanner
based on conoscopic holography technology
(NobelProcera Scanner, Nobel Biocare, Kloten,
Switzerland), coupled with dedicated software
(NobelProcera).
The DICOM and STL ﬁles were imported into
NobelClinician Software (Nobel Biocare) to perform the superimposition of the two data sets. The
DICOM and STL data were automatically matched
based on the adjacent teeth and manually checked
for a complete match using SmartFusion technology (Figs. 6a & b). The hard- and soft-tissue dif22 Volume 2 | Issue 3/2016

ferences between the two digitized model casts
were calculated on 2-D sections taken along the
long axes of the restored teeth and along the papillae (Figs. 7a–d).9 An independent assessor, not
previously involved in the study, scanned and
measured all of the model casts.

Results
Overall, eight patients (two men and six women)
with a total of 34 all-ceramic veneer restorations
placed in the esthetically sensitive area of the
maxilla (between the canines) were followed for
at least one year after delivery of the ﬁnal restorations. Of these, 16 replaced the central incisors,
14 the lateral incisors, and four the canines. One

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Hard- and soft-tissue changes with a superimposition technique

Figs. 6a & b

year after delivery of the deﬁnitive restorations,
no complications were observed (fracture, wear,
chipping or debonding). Mean soft-tissue levels
improved between bonding and the one-year
follow-up examination. The mean height of
the mesial and distal papillary changes was
0.64 ± 0.31 and 0.47 ± 0.28, respectively.

Discussion
The present clinical study examined a new objective technique to assess the hard- and softtissue changes in natural and artiﬁcial dentition.
The present technique is not intended to replace
previously established methods developed to
evaluate the esthetic success of a dental treatment. Conversely, the superimposition of CAD
model casts may complement techniques that
use subjective methods, such as standardized
clinical photographs.
The main limitation of the present technique
is the spatial resolution of the scanners and that
it does not evaluate color. Nevertheless, the
study cast evaluation involved a PES/WES
evaluation, facilitating the objective appreciation
of crown outline, as well as hard- and soft-tissue
changes. Esthetics are subjective and linked to
the patient, but this technique aims to evaluate
the thickness and level of the hard and soft tissue,
which is also useful in pre- and postoperative
comparison (e.g., bone reconstruction and socket
preservation).
The results of the present study showed a
mean soft-tissue increase at the level of both the
mesial and distal papillae between the pre- and
post-treatment situations. A possible explan-

ation could be the re-establishment of the correct
contact points and the renewed instructions on
proper oral hygiene.
All of the reference studies5–7 use subjective
indexes and require the capture of a series of
photographs to compare the differences between
follow-up examinations. If clinical photographs
are to provide an accurate record of pre- and
postoperative patient appearance, the relative
positions of the patient and camera must be kept
constant. Perspective distortion may be an unacceptable drawback, especially in comparison
of pre- and post-treatment clinical photographs.19
CBCT scanning ensures a comprehensive,
high-precision scan of both impressions and
plaster casts, delivering accurate 3-D models,
which can be used immediately or stored for
later use. The scanned 3-D model can be exported as a DICOM set or superimposed onto CBCT
data to provide an artifact-free model of the
patient’s dentition, including the bone, crowns
and soft tissue. The DICOM and STL ﬁles can be
superimposed too, helping the clinician with
clinical and treatment planning, as well as allowing for pre- and post-treatment comparison. A
straightforward DICOM to STL conversion is
easily possible.
Conoscopic holography scanning technology
is a valid option for the laboratory digitization of
model casts.20 This technology projects and reﬂects light beams from the shape of a complex
scanned object along the same linear pathway.
This collinearity measures steep angles and deep
cavities for precision scanning. Furthermore, it
allows, in a few minutes, a full simultaneous
digitization of a model cast in a single work
session without any manual user intervention.

Journal of
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Volume 2 | Issue 3/2016 23

Figs. 6a & b
Corresponding points in the
DICOM (a) and STL (b) data
during superimposition.

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Hard- and soft-tissue changes with a superimposition technique

Figs. 7a–d

Figs. 7a–d
Hard- and soft-tissue
measurements of the
differences between the two
digitized model casts,
calculated on 2-D sections
(a) taken along the long axes
of the restored teeth (b & c)
and along the papillae (d).

a

b

c

d

Superimposition of digitized data using a voxelCompeting interests
based registration method has already been explored in the literature.21–25 The main advantage is The authors declare that they have no competing
the generation of digital archive of patients for interests related to this study.
several purposes, including esthetic analysis.

Conclusion
The technique presented offers an objective evaluation of the hard- and soft-tissue changes over
time. This technique could complement previously established methods.

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Hard- and soft-tissue changes with a superimposition technique

References
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Chen ST, Buser D. Clinical and esthetic
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2.
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Raghoebar GM. Treatment outcome of
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Chang M, Wennström JL, Ödman P,
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Kois JC. Predictable single tooth peri-implant
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Buser D, Halbritter S, Hart C, Bornstein MM,
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Jemt T. Regeneration of gingival papillae after
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Pozzi A, Tallarico M, Barlattani A. Monolithic
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12.
Chen ST, Darby IB, Reynolds EC. A prospective
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Ahmad I. Digital dental photography. Part 1:
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13.
Evans CD, Chen ST. Esthetic outcomes of
immediate implant placements.
→ Clin Oral Implants Res.
2008 Jan;19(1):73–80.

20.
Holst S, Persson A, Wichmann M, Karl M.
Digitizing implant position locators on master
casts: comparison of a noncontact scanner
and a contact-probe scanner.
→ Int J Oral Maxillofac Implants.
2012 Jan-Feb;27(1):29–35.

14.
Buser D, Belser U, Higginbottom F. Consensus
statements and recommended clinical
procedures regarding esthetics in implant
dentistry.
→ In: Buser D, Belser U, Wismeijer D, editors.
ITI treatment guide. Vol. 1, Implant therapy in
the esthetic zone for single-tooth
replacements.
Berlin: Quintessence;
2004. p. 73–4.
15.
Belser UC, Grütter L, Vailati F, Bornstein MM,
Weber HP, Buser D. Outcome evaluation of
early placed maxillary anterior single-tooth
implants using objective esthetic criteria: a
cross-sectional, retrospective study in 45
patients with a 2- to 4-year follow-up using
pink and white esthetic scores.
→ J Periodontol.
2009 Jan;80(1):140–51.

24.
Szathvary I, Caneva M, Caneva M, Bressan E,
Botticelli D, Meneghello R. A volumetric 3-D
digital analysis of dimensional changes to the
alveolar process at implants placed
immediately into extraction sockets.
→ J Oral Science Rehabilitation.
2015 Sep;1(1):62–9.
25.
Caneva M, Botticelli D, Morelli F, Cesaretti G,
Beolchini M, Lang NP. Alveolar process
preservation at implants installed
immediately into extraction sockets using
deproteinized bovine bone mineral—an
experimental study in dogs.
→ Clin Oral Implants Res.
2012 Jul;23(7):789–96.

21.
Maes F, Collignon A, Vandermeulen D,
Marchal G, Suetens P. Multimodality image
registration by maximization of mutual
information.
→ IEEE Trans Med Imaging.
1997 Apr;16(2):187–98.
22.
Kim ES, Moon SY, Kim SG, Park HC, Oh JS.
Three-dimensional volumetric analysis after
sinus grafts.
→ Implant Dent.
2013 Apr;22(2):170–4.
23.
Meloni SM, Tallarico M, Lolli FM, Deledda A,
Pisano M, Jovanovic SA. Postextraction
socket preservation using epithelial
connective tissue graft vs porcine collagen
matrix. 1-year results of a randomised
controlled trial.
→ Eur J Oral Implantol.
2015 Spring;8(1):39–48.

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Fracture resistance of provisional implant-prosthetic abutments

Influence of fatigue on
resistance and deformation
of implant abutments
used for provisional prosthetic
restoration
Abstract
Objective
Rubén Agustín Panadero,a Antonio Fons Font,a
David Peñarrocha Oltraa & María Fernanda Solá Ruíza
a

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

Corresponding author:
Dr. Rubén Agustín Panadero
C/ Gascó Oliag, 1
46021 Valencia
Spain

One of the most difficult challenges for implant-supported prosthetic
restorations is the management and maintenance of periimplant softtissue esthetics, especially in the anterior region. In order to do this effectively, there are diverse techniques for tissue management, the most signiﬁcant being ﬁxed provisionalization, which can be immediate or delayed.
The aim of this study was to analyze fracture resistance of provisional
implant-prosthetic abutments (titanium, PEEK and methacrylate) and to
determine whether previously fatiguing the abutments inﬂuenced fracture
resistance.
Materials and methods

T +34 963 864 144
rubenagustinpanadero@gmail.com
How to cite this article:
Agustín Panadero R, Fons Font A, Peñarrocha Oltra D,
Solá Ruíz MF. Inﬂuence of fatigue on resistance and
deformation of implant abutments used for provisional
prosthetic restoration.
J Oral Science Rehabilitation.
2016 Sep;2(3):26–33.

Forty implant-prosthetic abutments underwent static load testing; 20 of
these were subjected to fatiguing before load testing. Forty internal hex
connection implants supported the 40 abutments: ten titanium provisional
abutments, ten castable methacrylate provisional abutments, ten PEEK
resin provisional abutments and ten titanium deﬁnitive abutments.
Results

The group that showed the greatest fracture resistance was the nonfatigued
deﬁnitive titanium abutments, with values over 1,000 N. The abutments
that showed the lowest fracture resistance were the fatigued castable methacrylate provisional abutments, with a mean value of 192.8 N.
Conclusion

Fatiguing the abutments did not signiﬁcantly inﬂuence their fracture resistance or elastic behavior. All of the abutments studied fulﬁlled the mechanical requirements for survival in the mouth.
Keywords

Dental implant, provisional/deﬁnitive implant abutment, fatiguing, immediate loading.
26 Volume 2 | Issue 3/2016

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Fracture resistance of provisional implant-prosthetic abutments

Introduction
In the ﬁeld of dentistry, implant dentistry is one
area that has undergone extensive development
in recent years, owing to the high demand for this
treatment and constant innovation and research
into new materials and attachments. Implant
placement has become the ﬁrst treatment choice
for replacing missing teeth, particularly single
teeth, because of the excellent clinical results
conﬁrmed by long-term research.1 Nowadays,
esthetics is an important factor in judging the
ﬁnal outcome of dental treatment. In the case of
implant dentistry, various factors inﬂuence esthetics. It is not enough to place a natural-looking
restoration with correct proportions and adequate color, for a successful outcome will also
depend on management of the periimplant soft
tissue.2 This is not always straightforward, as the
soft tissue is governed by multiple factors: the
periodontal biotype, alveolar bone crest level,
angle of implant insertion, depth of implant platform and level of the first point of bone-toimplant contact.3 Given this scenario, achieving
optimal esthetic results is a complicated process.
A diverse range of techniques are available for
soft-tissue management. From the prosthodontic perspective, provisional prostheses are useful
to help model the surrounding tissue and create
a harmonious proﬁle before placing the deﬁnitive
restoration.4 Furthermore, provisional restorations help improve communication with the
patient, as they offer the opportunity to view
future outcomes.2
For all these reasons, dental professionals
need to be aware of the different materials available on the market, as well as their physical and
chemical properties, for the correct fabrication
of both provisional and deﬁnitive prostheses that
will achieve optimal esthetics and good peri-

implant health.3–11 Provisional restoration can be
useful as a diagnostic tool too, as it allows the
dentist to assess the ﬁnal outcome in advance
and provides an opportunity to obtain the patient’s feedback and opinion. Its main function
is to guide and shape the soft tissue during healing and maturation, allowing the tissue to develop more quickly and suggest the deﬁnitive
gingival shape.12–29
This study was designed with the following objectives:
– to analyze the deformation and fracture resistance of implant-supported provisional abutments made of different materials (titanium,
PEEK and methacrylate)
– to determine whether fatiguing prior to static
load testing inﬂuenced fracture resistance and
deformation of the abutments.

Materials and methods
Materials

Forty Kohno internal hex connection implants
(Sweden & Martina, Due Carrare, Italy) were used
(4.25 mm in diameter and 11.5 mm in length).
Forty abutments were screwed on to the implants, 30 of which were provisional and ten
deﬁnitive (n = 40). The abutments were divided
into four groups (Table 1): castable methacrylate
provisional (CMP) abutments with a titanium
base; PEEK (polyether ether ketone) provisional
(PP) abutments with a machined titanium base;
Grade III titanium provisional (TP) abutments;
and Grade IV titanium deﬁnitive (TD) abutments.
Forty specimens were fabricated, each consisting of an implant set in a 5 cm diameter nylon
cylinder with epoxy resin (Exakto-Form, bredent,
Senden, Germany). In order to simulate implant

Table 1

Table 1

Group

Abutment type

Connection

CMP

Castable methacrylate provisional abutments
with a machined titanium base

Anti-rotational

PP

PEEK provisional abutments

Anti-rotational

TP

Grade III titanium provisional abutments

Anti-rotational

TD

Grade IV titanium deﬁnitive abutments

Anti-rotational

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Specimen distribution
by abutment type

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Fracture resistance of provisional implant-prosthetic abutments

Figs. 1 & 2

Fig. 1
Cyclic loading of implantsupported abutments.
Fig. 2
Static load testing
of implant-supported
abutments.

position conditions in the alveolar ridge in the
premaxilla, specimens were placed in the cylinder
at an angle of 30° to the direction of the load. The
abutments were screwed on to the implant–
cylinder complex using a dynamometric torque
wrench, applying a torque of 30 N, as recommended by the manufacturer.
Method

Before specimens underwent static load testing,
they were subjected to dynamic loading. This
fatiguing process was performed using a chewing simulator (CS-4, SD Mechatronik. Rosenheim, Germany; Fig. 1). Loading was applied to
the upper part of the abutment (angled at 30°)
with an impact force of 80 N and a frequency of
2 Hz. Each specimen was subjected to 60,000
cycles at an application speed of 40 mm/s. They
then underwent thermocycling (Thermocycler
2000, Heto-Holten A/S, Allerod, Denmark) for
6000 cycles with temperature changes between
5°C and 55°C every 30 seconds.
Static compression load testing was used to
evaluate the abutments’ fracture resistance. The
testing was performed using a static load testing machine (AG-X plus, Shimadzu, Kyoto,
Japan). A load cell of 5,000 N was used at a
crosshead speed of 0.5 mm/min (Fig. 2).
Statistical analysis consisted of preliminary
descriptive analysis of the force (fracture resistance) and deformation variables (mean,
standard deviation, range and median). Comparisons were made adopting a nonparametric
approach. Signiﬁcance was set at 5% (p = 0.05).
28 Volume 2 | Issue 3/2016

Results
The results obtained registered the force in Newtons (N) required to produce the fracture of each
specimen (Tables 2 & 3). Fracture of the prosthesis was understood as the ﬁrst mechanical failure
that the specimen underwent, whether this was
the maximum load that produced a clearly observed fracture or the maximum load before the
test machine registered a decrease in load even
if the fracture was not visibly obvious. Fracture
resistance values for two specimens (not subjected to fatiguing) were discarded owing to failure to fulﬁll the study procedure. The same also
occurred with two specimens subjected to fatiguing.
Table 4 shows the descriptive data by group
for fracture resistance in specimens not subjected
to fatiguing. The group that presented the highest
resistance to fracture was the TD group and the
group that showed the least resistance was the
PP group, with mean values of 1,106.7 N and
329.4 N, respectively. The groups that presented
the lowest resistance to fracture were CMP and
PP, obtaining values of between 300 N and
400 N. Fracture resistance levels were heterogeneous, as the Kruskal–Wallis test conﬁrmed
that there was no homogeneity in the distribution of resistance across the four groups (p = 0.006).
When the Mann–Whitney test was applied
to identify differences between pairs of groups,
CMP showed lower resistance than TP (p = 0.032)
and TD (p = 0.016), with the differences being
statistically signiﬁcant. PP restorations obtained
lower resistance than the TP (p = 0.016) and TD

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Fracture resistance of provisional implant-prosthetic abutments

Table 2

Specimen

CMP

PP

TP

TD

1

370.0

355.0

878.7

937.2

2

359.3

198.0

1089.0

No data

3

192.0

382.0

1403.0

1022.0

4

579.5

254.0

571.0

854.5

5

352.9

485.0

No data

1613.0

Specimen

CMP

PP

TP

TD

1

No data

304.8

675.3

1289.0

2

173.6

340.9

904.9

1578.0

3

194.5

282.6

810.3

1521.7

4

No data

432.8

566.5

1397.7

5

210.3

340.8

485.9

1086.3

CMP

PP

TP

TD

N

5

5

4

4

Mean

370.7

329.4

985.4

1106.7

Standard
deviation

137.8

103.6

350.3

344.4

Minimum

192.0

198.0

571.0

845.5

Maximum

579.5

458.0

1403.0

1613.0

Median

359.3

355.0

983.9

979.6

CMP

PP

TP

TD

N

3

5

5

5

Mean

192.8

340.4

688.6

1373.5

Standard
deviation

18.4

57.3

171.7

196.2

Minimum

173.6

282.6

485.9

1086.3

Maximum

210.3

432.8

904.9

1578.0

Median

194.5

340.8

675.3

1397.7

Specimen

CMP

PP

TP

TD

1

1.509

0.977

3.937

1.599

2

2.362

1.463

1.899

No data

3

3.991

2.349

3.530

1.379

4

1.811

2.313

1.349

0.733

5

2.645

2.694

No data

1.316

Table 3

Table 4

Table 5

Table 6

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Table 2
Fracture resistance (N) for
implant-prosthetic abutments
not subjected to fatiguing.

Table 3
Fracture resistance (N) for
implant-prosthetic abutments
subjected to fatiguing.

Table 4
Descriptive data by group
for abutments not subjected
to fatiguing (N).

Table 5
Descriptive data by group
for abutments subjected to
fatiguing (N).

Table 6
Deformation data (mm).

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Fracture resistance of provisional implant-prosthetic abutments

Table 7
Deformation data (mm).

Table 7

Specimen

CMP

PP

TP

TD

1

No data

2.330

0.867

0.825

2

0.794

2.222

3.796

0.845

3

1.449

2.006

2.258

0.978

4

No data

2.345

3.978

0.921

5

1.897

1.476

1.967

0.978

CMP

PP

TP

TD

N

5

5

4

4

Mean

1.3

1.6

1.9

1.3

Standard
deviation

0.3

0.7

1.1

0.4

Minimum

0.9

0.6

1.2

0.7

Maximum

1.6

2.3

3.5

1.6

Median

1.4

1.4

1.6

1.3

CMP

PP

TP

TD

N

3

5

5

5

Mean

1.4

2.1

2.6

0.9

Standard
deviation

0.6

0.4

1.3

0.1

Minimum

0.8

1.5

0.9

0.8

Maximum

1.9

2.3

4.0

1.0

Median

1.4

2.2

2.3

0.9

Table 8

Table 8
Descriptive deformation data
by group for abutments not
subjected to fatiguing (mm).

Table 9

Table 9
Descriptive deformation data
by group for abutments
subjected to fatiguing (mm).

groups (p = 0.016), with the differences being
statistically signiﬁcant. The performance of the
TP group was similar to that of the TD group
(p = 0.886). CMP and PP were also homogenous,
but with a signiﬁcantly lower resistance than the
other two groups (p = 1.000).
In a comparison of the statistical data for fracture resistance of restorations subjected to fatiguing (Table 5), the group that showed the
highest resistance was the TD group (1,373.5 N).
The groups with the lowest resistance were PP
and CMP; both groups obtained values of between 200 N and 350 N. Fracture resistance
levels were heterogeneous, and the Kruskal–
Wallis test conﬁrmed that there was no heterogeneity in the distribution of resistance across
the four groups (p < 0.001).
When resistance distribution was compared between pairs of groups of fatigued specimens,
30 Volume 2 | Issue 3/2016

statistically signiﬁcant differences were identiﬁed for all comparisons. Unlike the groups not
subjected to fatiguing, no group of fatigued specimens presented a homogenous distribution of
resistance when paired comparisons were made.
CMP restorations showed lower fracture
resistance than the rest of the groups, with the
differences being statistically significant
(PP: p = 0.036; TP: p = 0.036; TD: p = 0.036).
The PP group also showed lower resistance than
TP (p = 0.008) and TD specimens (p = 0.008),
with the differences being statistically signiﬁcant.
In making a comparative analysis between the
specimens subjected to fatiguing and those that
were not fatigued, a slight decrease in fracture
resistance was observed among all of the provisional restorations subjected to fatiguing (CMP,
PP and TP). However, the TD group showed

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stable performance despite cyclic loading, such
that its performance was not affected by fatiguing. The Mann–Whitney test was applied to
evaluate differences between fatigued and nonfatigued specimens and a p-value of 0.401 was
obtained, indicating that resistance to fracture
was similar between the two groups (fatigued/
nonfatigued). Likewise, within the individual
groups, no signiﬁcant differences were found
between fatigued or nonfatigued subgroups
(CMP: p = 0.143; PP: p 1.000; TP: p = 0.190;
TD: p 0.286), although the CMP and TP groups
did show a certain tendency toward difference,
but this did not reach statistical signiﬁcance.
In data analysis of the deformation that the
restorations suffered up to the point of fracture
or mechanical failure (in mm; Tables 6 & 7), deformation values for specimen 2 in the TD group
and specimen 5 in the TP group (not fatigued)
were discarded from analysis owing to various
technical failures in the study procedure. The
same occurred with two specimens (1 and 4) in
the CMP group (subjected to fatiguing).
In deformation data analysis of groups not subjected to fatiguing (Table 8), it was found that the
group that presented the highest deformation
values was the TP group. The group with the least
deformation was the TD group. The PP and CMP
groups showed similar median values, but a dispersed range of values. The Kruskal–Wallis test
showed that there were no overall signiﬁcant
differences (p = 0.187). The Mann–Whitney test
found that the only significant difference
occurred between the CMP and TD groups, the
TD group showing the lowest deformation values
(CMP–PP: p = 0.421; CMP–TP: p = 1.000; PP–TP:
p = 0.556; CMP–TD: p = 0.032; PP–TD: p = 0.190;
TP–TD: p = 0.114).
As for deformation data analysis of specimens
subjected to fatiguing (Table 9), the TD and CMP
groups underwent the least deformation. The PP
and TP groups showed similar median values, but
the range of values was more widely dispersed in
the TP group. The group that underwent the
greatest deformation was the TP group. When
homogeneity was analyzed between groups, the
Kruskal–Wallis test found a p-value of 0.022,
indicating homogeneity between the groups. The
Mann–Whitney test for paired groups only identiﬁed statistically signiﬁcant differences between
the TD and PP groups, with the TD group obtaining
lower deformation values (CMP–PP: p = 0.071;
CMP–TP: p = 0.143; PP–TP: p = 0.841; CMP–TD:
p = 0.571; PP–TD: p = 0.008; TP–TD: p = 0.056).

In order to determine whether fatigue inﬂuenced
deformation, specimens subjected to fatiguing
were compared with those not subjected to fatiguing, but no signiﬁcant differences were found
(CMP: p = 0.143; PP: p = 1.000; TP: p = 0.905;
TD: p = 0.286).

Discussion
Nowadays, many patients regard dental esthetics as one of the principal requirements of dental
treatment. In the case of implant dentistry, a
range of factors inﬂuence esthetic outcomes,
including color, contour, the natural appearance
of the deﬁnitive prosthesis, and most importantly, the topography and appearance of the periimplant soft tissue.2 Soft-tissue management is
not straightforward, as multiple factors affect
the ﬁnal outcome, in which the provisional prosthesis plays a key role.2, 4 Given the importance
of provisionalization as a part of dental implant
treatment, the present study set out to evaluate
the resistance to fracture of implant-supported
provisional prostheses of different materials (titanium, PEEK resin and methacrylate) subjected
to fatiguing. While deﬁnitive prostheses have
been extensively studied, little research has investigated fracture resistance and the inﬂuence
of fatigue on provisional abutments in vitro.
The present study protocol was designed
to fulfill the test geometry specified in
ISO 14801:2007 for testing single-post endosseous dental implants, in that the implant made
a 30° angle with the test machine’s load cell.30–39
This geometry has been used in most other
studies of similar characteristics to the present
one.34–37 The material used to set the implant in
the cylinder—epoxy resin—was chosen for its
elastic modulus > 3 GPa, also required by
ISO 14801:2007, and because this material has
been used in similar studies too.30–37 All of the
abutments were tested without placing restorations on them, as was the case in Truninger et
al., in which the abutments were subjected to
load testing without bearing restorations.35 Likewise, Rack et al. tested abutments without placing restorations on them, but soldered a steel
sphere of 10 mm in diameter to the coronal part
of the abutment so that the force applied would
be evenly distributed throughout the abutment
structure.33
The choice of test design was based on
Agustín-Panadero et al., who studied provision-

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al abutments subjected to static loading.5 Various
authors have proposed similar variables to the
present test design in terms of specimen design
and distribution, as well as crosshead speed and
movement.30–35 The crosshead speed in compression testing in this study was 0.5 mm/min, a
speed established from the literature review conducted in preparation for the study to ensure use
of the same speed used in the majority of other
similar studies (standardization being important
when it comes to comparison of studies).30–36
However, pure compression studies do appear to
be adequate for researching the fracture resistance of implant-prosthetic structures. The
ideal procedure in a study of these characteristics
is to subject specimens to dynamic loading–
artiﬁcial aging of the specimens–before performing the static load testing. For this reason, the
present study divided the specimens (n = 40) into
two subgroups and subjected half to a prior fatiguing process to simulate the aging of the
abutments. Like compression testing, the fatiguing process must meet criteria established
in ISO 14801:2007.39
The literature contains several studies that
have subjected specimens to aging prior to testing. 27, 28, 30, 34–39 Stimmelmayr et al. used the
same test machine (Mechatronic), the same
specimen distribution and frequency parameters (1.2 Hz), as well as impact speed (10
mm/s), as the present work36 to determine the
fracture resistance of fatigued zirconia abutments. Artiﬁcial aging or dynamic loading reproduces conditions in the mouth to which the
implant-prosthetic abutments are exposed,
reducing their fracture resistance evaluated
by static load compression testing.27, 28, 30, 34–39
Several studies have observed that the use of
substances that simulate saliva, creating a
moist environment, generates environmental
conditions that negatively affect the fatigued
implant abutment. 27, 28 Steinebrunner et al.
carried out fatigue testing of implant-prosthetic
abutments submerged in artiﬁcial saliva, imitating intra-oral conditions in order to evaluate
the inﬂuence of the ﬂuid medium.28 A control
group was made up of specimens subjected to
fatiguing in ambient air. The results showed
that the artiﬁcial saliva acted as an aggressive
environment, affecting the implants’ fracture
resistance.28 The oral environment is clearly an
important factor to consider when evaluating
dental implants’ mechanical properties and that
the present study did not simulate oral condi32 Volume 2 | Issue 3/2016

tions by exposing specimens to artiﬁcial saliva
can be considered a signiﬁcant limitation.
To date, few studies have provided scientific evidence in relation to provisional abutments, while deﬁnitive abutments have been
extensively studied. The range of fracture resistance values obtained in similar studies is
714–906 N.28, 34, 35 The data obtained in the
present study for the deﬁnitive abutments (TD),
whether subjected to fatiguing or not, and the
TP abutments not subjected to fatiguing fall
within this range and even exceed them. Sannino and Barlattani obtained values of 906 N
in static load testing of deﬁnitive titanium abutments.34 Truninger et al. evaluated the fracture
resistance of zirconia abutments, using titanium abutments as a control group, and obtained
a mean value of 714 N.35 It is important to consider the fracture resistance levels cited in the
literature that implant-prosthetic abutments
must support in the oral environment under
normal conditions. Ferrario et al. affirmed that
the occlusal load that a single tooth must support in the anterior region is 150 N; this study
included 52 patients who used a bite force
transducer to register occlusal force.38 In this
scenario, the present results conﬁrm that all of
the abutments analyzed, whether subjected to
fatiguing or not, fulﬁlled the requirements for
survival in the anterior region.

Conclusion
The Grade IV titanium deﬁnitive abutments
obtained the highest fracture resistance and
deformation values. The nonfatigued PEEK
resin provisional abutments and fatigued
castable methacrylate provisional abutments
obtained the lowest fracture resistance values.
The Grade III titanium provisional abutments
showed the highest deformation values. Fatiguing did not inﬂuence fracture resistance
signiﬁcantly or the abutments’ elastic performance. All of the abutments tested fulﬁlled the
mechanical requirements for survival in the oral
environment.

Competing interests
The authors declare that they have no competing interests related to this study. No ﬁnancial
support was received for this study.

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Silko-Sessak O, Rattanamongkolgul S.
Factors affecting soft tissue level around
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→ Clin Oral Implants Res.
2010 Jun;21(6):662–70.
4.
Manicone PF, Raffaelli L, Ghassemian M,
D’Addona A. Soft and hard tissue
management in implant therapy—Part II:
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2012 Jul 3.
5.
Agustín-Panadero R, Serra-Pastor B,
Roig-Vanaclocha A, Román-Rodriguez JL,
Fons-Font A. Mechanical behavior of
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Misch CE, Wang HL, Misch CM, Sharawy M,
Lemons J, Judy KW. Rationale for the
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Odin G, Misch CE, Binderman I, Scortecci G.
Fixed rehabilitation of severely atrophic jaws
using immediately loaded basal disk implants
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→ J Oral Implantol.
2012 Oct;38(5):611–6.
8.
Chung DM, Oh TJ, Lee J, Misch CE, Wang HL.
Factors affecting late implant bone loss:
a retrospective analysis.
→ Int J Oral Maxillofac Implants.
2007 Jan-Feb;22(1):117–26.

11.
Schropp L, Wenzel A, Kostopoulos L, Karring
T. Bone healing and soft tissue contour
changes following single-tooth extraction:
a clinical and radiographic 12-month
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→ Int J Periodontics Restorative Dent.
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12.
Araújo MG, Lindhe J. Dimensional ridge
alterations following tooth extraction.
An experimental study in the dog.
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2005 Feb;32(2):212–8.
13.
Von Wowern N, Gotfredsen K. Implant-supported overdentures, a prevention of bone
loss in edentulous mandibles? A 5-year
follow-up study.
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2001 Feb;12(1):19–25.
14.
Herrera Briones FJ, Romero Oild MN,
Vallecillo Capilla M. Puesta al día sobre
implantes de carga inmediata. Revisión
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2004 Feb;9(1):74–81. Spanish.
15.
Maló P, Rangert B, Nobre M. “All-on-Four”
immediate-function concept with Brånemark
System implants for completely edentulous
mandibles: a retrospective clinical study.
→ Clin Implant Dent Relat Res.
2003 Mar;5 Suppl 1:2–9.
16.
Maló P, Friberg B, Polizzi G, Gualini F,
Vighagen T, Rangert B. Immediate and early
function of Brånemark System implants
placed in the esthetic zone: a 1-year
prospective clinical multicenter study.
→ Clin Implant Dent Relat Res.
2003 Mar;5 Suppl 1:37–46.
17.
Cooper LF, Rahman A, Moriarty J, Chaffee N,
Sacco D. Immediate mandibular rehabilitation
with endosseous implants: simultaneous
extraction, implant placement, and loading.
→ Int J Oral Maxillofac Implants.
2002 Jul-Aug;17(4):517–25.
18.
Santosa RE. Provisional restoration options in
implant dentistry.
→ Aust Dent J.
2007 Sep;52(3):234–42; quiz 254.

9.
Misch CE. Consideration of biomechanical
stress in treatment with dental implants.
→ Dent Today.
2006 May;25(5):80, 82, 84–5; quiz 85.

19.
Canullo L, Peñarrocha-Oltra D, Soldini C,
Mazzocco F, Peñarrocha M, Covani U.
Microbiological assessment of the
implant-abutment interface in different
connections: cross-sectional study after 5
years of functional loading.
→ Clin Oral Implants Res.
2015 Apr;26(4):426–34.

10.
Van der Weijden F, Dell’Acqua F, Slot DE.
Alveolar bone dimensional changes of
post-extraction sockets in humans: a
systematic review.
→ J Clin Periodontol.
2009 Dec;36(12):1048–58.

20.
Uribe R, Peñarrocha M, Balaguer J, Fulgueiras
N. Carga inmediata en implantología oral.
Situación actual [Immediate loading in oral
implants. Present situation].
→ Med Oral Patol Oral Cir Bucal.
2005 Jul;10 Suppl 2:E143–53. Spanish.

21.
Binon PP. Implants and components: entering
the new millennium.
→ Int J Oral Maxillofac Implants.
2000 Jan-Feb;15(1):76–94.
22.
Peñarrocha-Diago MA, Flichy-Fernandez AJ,
Alonso-González R, Peñarrocha-Oltra D,
Balaguer-Martínez J, Peñarrocha-Diago M.
Inﬂuence of implant neck design and
implant-abutment connection type on
peri-implant health. Radiological study.
→ Clin Oral Implants Res.
2013 Nov;24(11):1192–200.
23.
Canullo L, Pace F, Coelho P, Sciubba E, Vozza I.
The inﬂuence of platform switching on the
biomechanical aspects of the implant-abutment system. A three dimensional ﬁnite
element study.
→ Med Oral Patol Oral Cir Bucal.
2011 Sep;16(6):e852–6.
24.
Sailer I, Mühlemann S, Zwahlen M, Hämmerle
CH, Schneider D. Cemented and screw-retained implant reconstructions: a systematic
review of the survival and complication rates.
→ Clin Oral Implants Res.
2012 Oct;23 Suppl 6:163–201.
25.
Priest G. Esthetic potential of single-implant
provisional restorations: selection criteria of
available alternatives.
→ J Esthet Restor Dent.
2006 Nov-Dec;18(6):326–38; discussion
339.
26.
Lewis MB, Klineberg I. Prosthodontic
considerations designed to optimize
outcomes for single-tooth implants. A review
of the literature.
→ Aust Dent J.
2011 Jun;56(2):181–92.
27.
Shemtov-Yona K, Rittel D, Levin L, Matchetei
EE. The effect of oral-like environment on
dental implants’ fatigue performance.
→ Clin Oral Implants Res.
2014 Feb;25(2):e166–70.
28.
Steinebrunner L, Wolfart S, Ludwig K, Kern M.
Implant abutment interface design affects
fatigue and fracture strength of implants.
→ Clin Oral Implants Res.
2008 Dec;19(12):1276–84.
29.
Peñarrocha-Oltra D, Covani U, Peñarrocha M,
Peñarrocha-Diago M. Immediate versus
conventional loading with ﬁxed full-arch
prostheses in mandibles with failing dentition:
a prospective controlled study.
→ Int J Oral Maxillofac Implants.
2015 Mar-Apr;30(2):427–34.
30.
Martínez-Rus F, Ferreiroa A, Özcan M,
Bartolomé JF, Pradíes G. Fracture resistance
of crowns cemented on titanium and zirconia
implant abutments: a comparison of
monolithic versus manually veneered
all-ceramic systems.
→ Int J Oral Maxillofac Implants.
2012 Nov-Dec;27(6):1448–55.

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31.
Nothdurf FP, Doppler KE, Erdelt KJ, Knauber
AW, Pospiech PR. Fracture behavior of
straight or angulated zirconia implant
abutments supporting anterior single crowns.
→ Clin Oral Investig.
2011 Apr;15(2):157–63.
32.
Nothdurf FP, Doppler KE, Erdelt KJ, Knauber
AW, Pospiech PR. Inﬂuence of artiﬁcial aging
on the load-bearing capability of straight or
angulated zirconia abutments in implant/
tooth-supported ﬁxed partial dentures.
→ Int J Oral Maxillofac Implants.
2010 Sep;25(5):991–8.
33.
Rack T, Zabler S, Rack A, Riesemeier H, Nelson
K. An in vitro pilot study of abutment stability
during loading in new and fatigue-loaded
conical dental implants using synchrotronbase radiography.
→ Int J Oral Maxillofac Implants.
2013 Jan-Feb;28(1):44–50.
34.
Sannino G, Barlattani A. Mechanical
evaluation of an implant-abutment
self-locking connection: ﬁnite element
analysis and experimental test.
→ Int J Oral Maxillofac Implants.
2013 Jan-Feb;28(1):e17–26.
35.
Truninger TC, Stawarczyk B, Leutert CR, Sailer
TR, Hämmerle CH, Sailer I. Bending moments
of zirconia and titanium abutments with
internal and external implant-abutment
connections after aging and chewing
simulation.
→ Clin Oral Implants Res.
2012 Jan;23(1):12–8.
36.
Stimmelmayr M, Sagerer S, Erdelt K, Beuer F.
In vitro fatigue and fracture strength testing
of one piece zirconia implant abutment and
zirconia implant abutments connected to
titanium cores.
→ Int J Oral Maxillofac Implants.
2013 Mar-Apr;28(2):488–93.
37.
Simsiriwong J, Shrestha R, Shamsaei N, Lugo
M, Moser RD. Effects of microstructural
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2015 Nov;51:388–97.
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Ferrario VF, Sforza C, Serrao G, Dellavia C,
Tartaglia GM. Single tooth bite forces in
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→ J Oral Rehabil.
2004 Jan;31(1):18–22.
39.
International Organization for Standardization. International standard ISO 14801:2007:
dentistry—implants—dynamic fatigue test for
endosseous dental implants.
→ Geneva: International Organization
for Standardization,
2007. 9 p.

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Pulp response after capping with PDGF

Human pulps capped with
PDGF: A pilot study

Abstract
Objective
Gaia Pellegrini,a Claudia Dellavia,a Paolo Generali,b
Cristina Allievi,a Dino Rec & Giulio Rasperinia, d
a

Department of Biomedical, Surgical and Dental Sciences,
Università degli Studi di Milano, Milan, Italy
b
Private practice
c
Department of Oral Rehabilitation, Istituto Stomatologico
Italiano, Università degli Studi di Milano, Italy
d
Fondazione IRCCS Policlinico Ca’ Granda, Milan, Italy

Corresponding author:
Dr. Gaia Pellegrini
Via Mangiagalli, 31
20133 Milan
Italy

Growth factors have shown the potential to promote odontoblast-like cell
differentiation and induce the formation of reparative dentin. The aims of
this pilot study were to develop a regenerative approach to pulp capping
using platelet-derived growth factor (PDGF) BB and to describe histologically the pulp tissue response.
Materials and methods

Two third molars (Site A and Site B) were treated. Class I cavities were
prepared and the exposed pulps were capped with cotton pellets embedded in a PDGF solution. Teeth were extracted after 40 days and processed
for routine histological examination. The hard bridge formation and the
pulp reaction were evaluated.

T +39 347 5923198
gaiapellegrini.perio@gmail.com

Results

How to cite this article:
Pellegrini G, Dellavia C,
Generali P, Allievi C, Re D, Rasperini G.
Human pulps capped with PDGF: a pilot study.
J Oral Science Rehabilitation.
2016 Sep;2(3):34–41.

In Site A, incomplete and thick dentin bridge formation was observed. The
pulp tissue close to the remaining exposed pulp was moderately disorganized, with many ﬁbroblasts and few inﬂammatory cells. In Site B, an incomplete dentin bridge covered part of the defect. The pulp was overall
normal, but a limited area showing a clot-like tissue with many ﬁbroblasts
and few inﬂammatory cells close to the dentin bridge interruption was observed.
Conclusion

PDGF-BB did not elicit an inﬂammatory response and did not induce extensive dentin matrix deposition. It thus appears to be a safe pulp capping
agent.
Keywords

Histology, human platelet-derived growth factor, pulp capping, wound
healing.
34 Volume 2 | Issue 3/2016

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Introduction
The dental pulp provides nutrition and sensory
properties to dentin and has reparative capacity
to react to injury. When the injury results in odontoblast death, a new generation of odontoblast-like cells may differentiate from progenitor
cells within the pulp and secrete a reparative
dentin matrix.1 Pulp capping is a common procedure that induces reparative dentin formation
after pulp exposure due to cavity preparation,
caries removal or trauma. Calcium hydroxide, zinc
oxide eugenol cements, composite resins, mineral trioxide aggregate (MTA) and glass ionomer
cements are used in clinical daily practice.2, 3
However, several concerns have been listed regarding the use of these materials for pulp capping, including cytotoxic effects,4 the lack of
adequate bleeding control after acid etching5 and
the new hard-tissue formation at the expense of
pulp chamber width, causing narrowing of root
canals.6 Although calcium hydroxide is the most
widely used pulp capping agent to encourage
hard-tissue bridging, the material is not able to
effectively induce new tissue formation.7 Bridge
formation remains unpredictable, with varying
thickness and numerous tunnel defects,8 suggesting that it may be of insufficient quality to
protect the pulp against bacterial microleakage
along the restoration margins. Several articles
have addressed the use of MTA for pulp capping
and demonstrated a hard-tissue barrier beneath
the MTA; however, pulpal soft tissue enclosed
within the hard-tissue barrier and unpredictable
dentin bridge formation were observed.9, 10
Recently, a growth factor delivery approach
has been introduced to induce reparative dentin
formation in noninﬂamed mechanically exposed
pulps.11, 12 Rutherford et al. examined histologically the reparative dentin formation of pulp treated with osteogenic protein-1 (bone morphogenetic protein [BMP] 7) in monkeys.13 They
reported that BMP-7 has the potential to induce
the formation of reparative dentin and related
the amount of newly formed dentin to the amount
of implanted protein. Nakashima observed histologically the induction of tubular dentin formation in teeth capped with BMP-2 and -4 in monkeys.11 An in vivo study has demonstrated with
histomorphometric analysis the role of transforming growth factor-ʹ in promoting odontoblast-like cell differentiation and the secretion of
extracellular matrix.14 The effects of enamel
matrix protein on pulp capping have been evaluated histologically and immunohistochemically in

animal13 and human studies.15, 16 After application
of enamel matrix protein, the damaged pulp showed at ﬁrst a reparative process with formation
of a scar and moderate inﬂammatory inﬁltrate.
Subsequently, neogenesis of normal dental pulp
occurred and odontoblast-like cells produced
reparative dentin.17 In the literature, there is converging evidence that reparative processes recapitulate early developmental events that lead to
dental tissue formation.18 However, the effects of
platelet-derived growth factor (PDGF) on reparative processes after pulp capping have not been
deﬁned. PDGF is a potent mitogenic, chemotactic
agent. It stimulates cells of mesenchymal origin
to produce protein19 and promotes angiogenesis
and the regeneration process of several tissues,
such as bone, cementum and periodontal ligament.20 PDGF also regulates cell proliferation and
dentin matrix protein production in dental pulp
culture.21, 22 In their histochemical and immunohistochemical study, Yokose et al. evaluated the
effects of three PDGF dimers (PDGF-AA, -BB and
-AB) on odontoblast differentiation of dental pulp
cells.23 The authors reported the different effects
of the PDGF dimers on dentin formation during
the repair process in damaged dental pulp. They
observed that PDGF-AB and -BB stimulated the
differentiation of odontoblastic cells, increasing
the number of mature odontoblastic cells. In contrast, PDGF-AA exerted inhibitory effects on
odontoblast differentiation.23 These ﬁndings suggest a role of PDGF-BB in dentinogenesis in the
dental pulp and in differentiation of odontoblasts
during repair processes after injury to the mature
pulp. The aims of this preliminary human study
were to develop a regenerative approach to pulp
capping using PDGF-BB and to describe histologically the pulp tissue response.

Materials and methods
After a through explanation of the experimental
rationale, clinical procedure and possible risks,
written informed consent was obtained from
both subjects to be entered in the study. The
study conformed to the principles outlined in the
Declaration of Helsinki of 1975, as revised in 2013,
on experimentation involving human subjects
and was approved by the Ethics Committee of
the Department of Human Morphology and Biomedical Sciences "Città Studi", Milan, Italy. Before
treatment, all patients gave written informed
consent. Two completely erupted third molars
that needed to be extracted for orthodontic treat-

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Pulp response after capping with PDGF

ment were selected from two patients (one tooth
from each patient) with the following inclusion
criteria: (a) no systemic diseases or metabolic
bone disorders; (b) not pregnant; and (c) no history of malignancy, radiotherapy or chemotherapy for a malignancy in the past ﬁve years. Furthermore, in order to standardize the
age-related prognostic factor, subjects aged
between 18 and 39 were enrolled.24 The experimental teeth were clinically and radiographically examined and presented superﬁcial enamel
decay; however, the teeth were asymptomatic,
without periapical lesions and responded positively to the cold stimulus test performed by
applying HYGENIC ENDO-ICE F frozen gas
(Coltène/Whaledent, Mahwah, N.J., U.S.) for 5 s
to the buccal surfaces.
Procedures employed

Forty days before the extraction, after local and
intraligament anesthesia with lidocaine containing 1:80,000 epinephrine to control pain and
bleeding from the exposed pulp, the selected
molars were isolated with a rubber dam and disinfected with topical antiseptic. Class I cavities
on the occlusal surfaces of the experimental teeth
were prepared by means of diamond burs (1 mm
in diameter) and the pulps were exposed. On one
tooth (Site A), a perforation of 1 mm × 1 mm (evaluated at the level of the pulp chamber) was performed; and on the other tooth (Site B), the perforation was 3 mm × 3 mm.
After rising with sterile water to remove the
debris, establishing hemostasis with a sterile
cotton pellet soaked in saline solution and
drying with a sterile cotton pellet, the pulp was
capped with sterile cotton embedded in a PDGFBB solution and covered with zinc oxide cement
(CAVIT, 3M ESPE, Seefeld, Germany). During
the days after capping, the patients completed
a questionnaire on pain occurrence. After 40
days, the experimental teeth were tested for
pulp vitality by applying HYGENIC ENDO-ICE F
and were carefully extracted without root
separation or crown fracture.
Histological analysis

Immediately after extraction, the teeth were immersion ﬁxed in a 10% formalin/0.1 M phosphate-buffered saline (pH 7.4) for 24 h at room
temperature. The dental crown was separated
from the roots using a round bur in a low-speed

36 Volume 2 | Issue 3/2016

handpiece and then decalciﬁed for 30 days in a
solution containing formic acid (625 cm3 in
625 cm3 of distilled/puriﬁed water) and sodium
citrate (250 g in 125 cm3 of distilled/puriﬁed water). Decalciﬁcation of dental tissue was veriﬁed
by radiograph. After rinsing under running water
for 48 h, the sample was routinely dehydrated in
increasing concentrations of ethanol (from 50 to
100%), immersed in xylol for 12 h and then embedded in paraffin. Serial buccolingual sections
were obtained from 4 to 5 mm and then hydrated in xylol and decreasing concentrations of ethanol (from 100 to 70%) and ﬁnally immersed in
distilled water. Sections were stained with hematoxylin and eosin (H&E) to evaluate the tissue
morphology and with Masson’s trichrome stain
to distinguish the connective matrix from cells.
The sections were viewed and photographed
under a light microscope (Eclipse E600, Nikon,
Tokyo, Japan) equipped with a calibrated digital
camera (DXM 1200, Nikon). Multiple central sections were used to perform an overall assessment
for each tooth. The hard-tissue bridge formation
(continuity, morphology, localization and thickness) and the dental pulp reaction (inﬂammatory cell response and tissue disorganization) were
described.

Results
Both patients (A and B) who completed the study
were female, nonsmokers, and 23 and 26 years
old, respectively. A total of two teeth were analyzed. After the experimental pulp capping, the
patients did not report any symptoms or analgesic intake. At the extraction appointment, both
teeth were vital and both cavities still closed with
CAVIT. At the histological evaluation, the thickness (mm) of the newly formed hard tissue was
measured at three different points of the bridge:
alongside the dentinal wall (on the mesial side
and distal side) and in the center. Table 1 shows
the mean thickness of the newly formed bridge.
Site A

In all of the sections, the drill-created cavity contained debris and bacteria along all of the cavity
walls (Fig. 1). An incomplete dentin bridge lined
the pulp exposure site and was formed by
well-organized tubular reparative dentin, with a
clear predentin layer and odontoblastic-like cells
(Fig. 2). No extensive dentin matrix deposition

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Table 1

†
‡

M†

Center

D‡

Site A

209

190

–

Site B

–

338

92

M = mesial side.
D = distal side.

Fig. 1

Table 1
Thickness (mm) of the newly
formed bridge measured at
three different points. The
thickness was not evaluated
in sites where the bridge was
absent.
Fig. 1
Photomicrograph of Site A.
Buccolingual section.
The drill-created cavity (C)
containing much debris is
separated from the pulp (P)
by a thick and incomplete
dentin bridge (DB). The newly
formed hard tissue starting
from the original dentin tissue
covers only half of the
exposed pulp. H&E staining
(at original 20× magniﬁcation).

Figs. 2 & 3

Fig. 2

Fig. 3

Detail of Figure 1. The dentin
bridge (DB) is formed by
tubular and well-oriented
reparative dentin. The
pulp (P) appears slightly
disorganized with few
scattered inﬂammatory cells.
C = cavity. H&E staining (at
original 100× magniﬁcation).

Detail of Figure 1. The pulp
tissue (P) close to the newly
formed dentin (DB) and
surrounding the remaining
defect appears disorganized, with many ﬁbroblasts
and few scattered inﬂammatory cells. H&E staining
(at original 200× magniﬁcation).

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Pulp response after capping with PDGF

Figs. 4 & 5

Discussion

Fig. 4
Detail of Figure 1. The pulp
tissue (P) adjacent to the
reactive area and under the
original dentin (D) appears
healthy and well organized,
with no signs of necrosis or
abscess. H&E staining (at
original 100× magniﬁcation).
Fig. 5
Detail of Figure 1. Photomicrograph of the pulp in the area
adjacent to the reactive tissue.
No extravasated red blood
cells, suffering pulp or inﬂammatory cells are detectable.
H&E staining (at original 400×
magniﬁcation).

obliterating the pulp chamber was observed. The
general state of the pulp close to the remaining
defect was moderately disorganized. This area
contained many ﬁbroblasts, some extravasated
red blood cells and few inflammatory cells
(Fig. 3). No signs of abscess were observed. The
pulp tissue adjacent to the reactive area appeared
normal, with no signs of inﬂammation or necrosis (Figs. 4 & 5).
Site B

Debris occurred along and over the cavity walls,
but without touching the pulp tissue (Fig. 6). The
hard bridge formation was moderate and incomplete, leaving a small area of communication
between the capping material and the dental
pulp. The reparative dentin was tubular and well
oriented (Fig. 7), without invading the pulp space.
The general state of the pulp was normally organized without inﬂammatory cells beneath the
dentin bridge formation. Only a limited area of
tissue disorganization and pulp reaction similar
to that observed in Site A was adjacent to the
hard-barrier interruption and separated the normal pulp tissue from the contaminated drillcreated cavity (Fig. 8). No tunnel-like defect appeared in any section. The hard-tissue thickness
was greater in the central portion, and the thickness at the distal side was not calculated because
of the interruptions (Table 1).
38 Volume 2 | Issue 3/2016

The present pilot study was designed to evaluate
the response of noninﬂamed mechanically exposed human pulps after capping performed
using PDGF-BB. In Site A, an area of moderate
disorganization was evident below the remaining
pulp exposure site. In Site B, only a limited area
of slight reaction was observed at the lateral side
of the defect, close to the dentin bridge interruption. No signs of abscess or inﬂammatory inﬁltrate in the connective tissue were detected in
either sample. The pulp was overall normal and
asymptomatic, despite the use of nonsealing
cement. Tubular reparative dentin and an adjacent
well-organized odontoblast-like cell layer were
detected in both samples. No extensive dentin
matrix deposition obliterating the pulp chamber
was found. In the literature, tunnel defects are
often described throughout the newly formed
dentin bridges of teeth capped with calcium hydroxide.8 In the present study, in both samples,
the reparative dentin was compact and without
defects. Since the aim of the present study was
to assess the response of noninﬂamed pulp tissue
after PDGF-BB treatment, no control samples
were evaluated to compare the amount of newly formed dentin matrix. Also, the experiment was
conducted on a limited number of cases and thus
did not allow for statistical analysis. In the treated teeth, access to the pulp chamber was of two
different sizes to assess the response of capped
pulp tissue to varying extents of such a traumatic event.

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Fig. 6

Fig. 6
Photomicrograph of Site B.
Buccolingual section.
Within the cavity (C), debris
is visible. Between the cavity
and the pulp (P), the dentin
bridge (DB) runs horizontally
from the cut surfaces,
covering most of the exposed
dental pulp. This hard tissue
is very thin on the right side
close to the original dentin
tissue, is the thickest in the
central area of the defect and
is incomplete on the left side
(black arrow). The dental pulp
presents no inﬂammatory
response and has an organized structure, but for the
area close to the dentin bridge
interruption, where a disorganized and ﬁbrous clot-like
tissue is observed. H&E staining
(at original 20× magniﬁcation).
Fig. 7
Detail of Figure 6. The reparative dentin (DB) is tubular
and well organized. Odontoblast-like cells (O) are
between the dental pulp (P)
and the predentin (PD) tissue.
The pulp is well organized and
without inﬂammatory cells.
H&E staining (at original 400×
magniﬁcation).

Figs. 7 & 8

Fig. 8
Detail of Figure 6. In correspondence with the dentin
bridge interruption, the pulp
is not in direct contact with
the cavity. A disorganized clotlike tissue (Cl) with many
ﬁbroblasts (F) and few inﬂammatory cells is apparent
between the cavity and the
pulp in close contact with
bacteria and debris. Masson’s
trichrome staining (original
600× magniﬁcation).

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These preliminary ﬁndings indicate that PDGFBB does not elicit pulpal inﬂammatory response,
nor induce extensive dentin matrix deposition,
suggesting that this growth factor could be
safely applied in human pulp capping. According
to previous human models that proved the efficacy of growth factors in noninﬂamed exposed
pulp,15 this study was performed on healthy and
freshly exposed pulps. However, Rutherford and
Gu demonstrated the failure of a treatment strategy utilizing BMP-7 proteins for management of
inﬂamed pulpal wounds.25 Despite this, it may be
supposed that the therapeutic activity of PDGFBB is mainly due to the promotion of tissue regeneration than to the resolution of the inﬂammatory process. Further studies should thus
investigate the efficacy of PDGF in promoting
newly formed dentin bridges in inﬂamed pulps
and compare this treatment with a biological
agent to the gold standard pulp capping agent
(MTA).9 The role and mechanism of action of
PDGF in healing of damaged dental pulp and
dentin bridge formation are not completely understood. PDGF plays a role in cell chemotaxis,
proliferation and differentiation at each stage of
wound healing.19, 20 In periodontics, clinical studies have been conducted since PDGF demonstrated an important role in regeneration of cementum, periodontal ligament and alveolar
bone.26 In a clinical trial, Nevins et al. evaluated
the healing and regeneration of infrabony periodontal defects treated with highly puriﬁed recombinant human PDGF-BB and a ʹ-tricalcium
phosphate scaffold and demonstrated the efficacy of PDGF-BB in accelerating and improving
periodontal soft-tissue healing and bone regeneration.27 In addition, clinical trials have suggested the promotion of bone turnover during the
repair process of tooth-supporting osseous defects.28
A histochemical and immunohistochemical
study has evaluated the effects of three PDGF
dimers (PDGF-AA, -BB and -AB) on odontoblast
differentiation of dental pulp cells.23 The authors observed dentin formation during the
repair process in damaged dental pulp. They also
observed that PDGF-AB and -BB stimulated the
differentiation of odontoblast cells, increasing
the number of mature odontoblast cells. In contrast, PDGF-AA exerted inhibitory effects on
odontoblast differentiation. 23 These ﬁndings
suggest a role of PDGF-BB in dentinogenesis in
the dental pulp and in differentiation of odontoblasts during repair processes after injury to
the mature pulp. The importance of PDGF in the
40 Volume 2 | Issue 3/2016

dental pulp regenerative process is due to the
role that this growth factor plays during embryonic development. PDGFs and plateletderived growth factor receptors (PDGFRs) play
a role in gastrulation,29 development of the cranial and cardiac neural crests,30 and formation
of the palate.31 Studies have shown that PDGF-ʸ
and PDGFR-ʸ are expressed in developing
mouse molars, regulate epithelial–mesenchymal interaction during mammalian tooth morphogenesis, and have a critical function in differentiation of dental pulp cells and in the
development of dental cusps.31, 32

Conclusion
Within its limitations, this study suggests that
PDGF-BB appears to be a safe pulp capping
agent. PDGF-BB may stimulate dentinogenesis,
promoting differentiation of odontoblasts after
dental pulp injury. It appears that differentiated
odontoblasts produce tubular and compact reparative dentin, without tunnel defects, and do
not obliterate the pulp chamber.

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

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Pulp response after capping with PDGF

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Xu X, Bringas P, Soriano P, Chai Y.
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Volume 2 | Issue 3/2016 41

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Axial plane in computed tomography

Importance of the axial
reference plane in computed
tomography for dental
implant surgery: A cadaveric
study
Abstract
Objectives
Carlos Vilaplana Vivo,a Jaime Vilaplana Vivo,a
Alfonso Miguel Sánchez,a Juan Ángel Vilaplana Gómeza
& Fabio Camacho Alonsoa
a

School of Dentistry, University of Murcia, Murcia, Spain

The aims of the study were to assess the accuracy of dental computed
tomography (CT) scans and to compare the discrepancies obtained when
either the occlusal plane or the basal plane was used as the axial reference
plane.
Materials and methods

Corresponding author:
Dr. Fabio Camacho Alonso
Clínica Odontológica Universitaria
Unidad Docente de Cirugía Bucal
Hospital Morales Meseguer (2ª planta)
Avda. Marqués de los Vélez s/n
C.P. 30008
Murcia
Spain
T +34 868 88 8589
F +34 868 88 8576
fcamacho@um.es

How to cite this article:
Vilaplana Vivo C, Vilaplana Vivo J, Miguel Sánchez A,
Vilaplana Gómez JA, Camacho Alonso F. Importance
of the axial reference plane in computed tomography
for dental implant surgery: a cadaveric study.
J Oral Science Rehabilitation.
2016 Sep;2(3):42–9.

Thirty-nine mandibles from adult cadavers were examined. Eighteen
tomographic slices were performed for each mandible, using the occlusal
and the basal planes as axial reference planes. The radiographic measurements obtained using the two reference planes were compared with bone
measurements taken using a digital calibrator.
Results

Discrepancies, which varied between 0.03 mm and 1.47 mm, were found
between measurements taken from CT scans and measurements taken
directly from the bone. When the distribution of discrepancies was considered in relation to the axial reference plane used, it was found that when
the basal plane was used, a higher percentage of discrepancies of over
0.5 mm occurred (99.44%) than when the occlusal plane was used
(44.44%), with the difference being statistically signiﬁcant (p = 0.001).
Conclusion

The discrepancies between CT radiographic measurements and direct bone
measurements should be taken into consideration in order to achieve satisfactory dental implant treatments. With regard to positioning the patient
when CT scans are taken, use of the occlusal plane as axial reference will
produce the most accurate measurements.
Keywords

Axial reference plane, occlusal plane, basal plane, computed tomography,
dental implantology.
42 Volume 2 | Issue 3/2016

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Axial plane in computed tomography

The aims of the present ex vivo study were to
assess the accuracy of dental CT scans and to
Edentulous patients seeking dental treatment compare the discrepancies obtained when either
to restore function and esthetics have tradition- the occlusal plane or the basal plane was used as
ally received removable complete or partial den- the axial reference plane.
tures. However, the use of removable dentures
may give the patient a sense of insecurity, reduced masticatory function and taste capacity,
Materials and methods
1
as well as low self-esteem. For these reasons,
approaches to treatment have turned toward
Mandibles
dental implants, which produce marked improvements in patients’ quality of life and high A total of 39 normal and dry mandibles from adult
treatment success rates.2, 3
cadavers aged 35–83 (mean age of 50) were
An adequate radiographic technique that will examined following state regulations, the study
provide a sufficiently accurate assessment of the protocol having been approved by the Murcia
bone dimensions is of great help when planning (Spain) City Hall Health Service. Thirty of these
the surgical intervention. Intra-oral and pano- mandibles were edentulous and the other nine
ramic radiographs give information in two dimen- retained teeth. In order to homogenize the study,
sions, visualizing bone morphology in a bucco- multiple exodontias were performed on the nine
lingual direction, but lack the third dimension. mandibles that retained teeth.
Both techniques are only useful for a primary
preoperative evaluation to obtain preliminary
Marking the occlusal plane
4
information about the available bone height.
Three-dimensional information is obtained using The occlusal plane was marked on the nine mandibles that retained teeth before the exodontias
computed tomography (CT).
In edentulous mandibles, the location and were performed. This was done by marking a line
course of the mandibular canal remain relatively parallel to the teeth from the incisal edge of the
unchanged in the cranial and caudal borders of central incisor to the vestibular cusps of the secthe mandible, although some atrophy at the lin- ond molar (Fig. 1a). Once the occlusal plane had
gual and buccal external borders may occur.5 been marked, the teeth were extracted.
Recently, some anatomical structures in the jawFor the 30 edentulous mandibles, the occlubone, which are difficult to detect using conven- sal plane was established in the anterior region
tional radiography, have been explored using by measuring a height of 1 cm (the usual height
CT.6–9 Investigations of mandibular accessory of the mandibular incisal crowns) and in the posforamina and canals have drawn attention to terior region by dividing the retromolar trigone
anatomical variations of perimandibular neuro- into three parts: upper, middle and lower. Therevascularization.10–13
after, a meeting point between the upper third
Although there is a wide range of dental CT and the middle part was chosen; this point usualequipment marketed as providing exact bone ly measured 1 cm in height (Fig. 1b).20
Once the occlusal planes of the mandibles
data at a 1:1 scale, several studies have shown
discrepancies between radiographic CT meas- had been established, a Moyco wax piece
urements and clinical measurements taken di- (Thompson Dental Manufacturing, Montgomeryrectly from the bone.4, 14–16 Furthermore, depen- ville, Pa., U.S.) was molded to follow the previding on the positioning of the patient when the CT ously established plane. After placing the wax
measurements are taken, these discrepancies simulation of the occlusal plane (Fig. 1c), this was
between radiographic measurement and measu- divided into 18 parts using 2 mm lead strips.
rements taken from real bone can increase even These strips were placed 6 mm apart so that they
further.17, 18 In 2008, Cucchiarelli et al. compared corresponded to the 18 tomographic slices perthe discrepancies between radiographic measu- formed for each mandible (Fig. 1d).
rements with CT and measurements taken direcLastly, Fox planes were attached to the wax
tly from 15 edentulous maxillae, using two diffe- on each of the 39 mandibles (to be used as a
rent axial reference planes.19 The study showed guide for delimiting the occlusal plane radiographdistortions with regard to the real bone measu- ically) and each assembly was placed into a porements, and these discrepancies were different lymethyl methacrylate (PMMA) box for radiografor each of the two axial reference planes used. phic study.
Introduction

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Axial plane in computed tomography

Figs. 1a & b

Figs. 1a–d
Marking the occlusal plane:
(a) marking mandibles with
teeth intact before multiple
exodontias were performed;
(b) marking edentulous
mandibles; (c) placing the wax
piece to simulate the occlusal
plane; (d) wax piece divided
into 18 parts with lead strips
corresponding to the 18
tomographic slices taken
of each mandible).

a

b
Figs. 1c & d

c

d
Figs. 2a–c

a

Figs. 2a–c
Basal plane: (a) positioning
of mandibles in PMMA boxes
to support the lower edge
against the container’s
anterior wall; (b) use of the
occlusal plane as the axial
reference plane; (c) use of
the basal plane as the axial
reference plane.

b

c

Basal plane

In order to establish a good axial reference from
the basal plane, all of the mandibles were positioned in PMMA boxes to support the lower edge
(basal plane) against the container’s anterior wall
(Fig. 2a).
Dental CT

The CT equipment used was a Toshiba Multi CT
scan Aquilion 16 TSX-101A/6A (Toshiba America
44 Volume 2 | Issue 3/2016

Medical Systems, Tustin, Calif., U.S.). Thirty-six
sagittal tomographic slices were performed for
each mandible, 18 taking the occlusal plane as
the axial reference plane (Fig. 2b) and 18 using
the basal plane (Fig. 2c). The exposure parameters were set at 57 Kv, 56 s and 1.0–3.2 mA, and
a rectangular collimator was used. The radiographic images were processed using SIMPLANT
software (Materialise Dental, Madrid, Spain). All
of the measurements were scored independently by two oral surgeons. When measuring the
sagittal tomographic slices, the observers were

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Axial plane in computed tomography

Figs. 3a–c

blinded as to which axial reference plane, occlusal (Fig. 3a) or basal (Fig. 3b), had been used.
Lastly, the observers’ mean scores were calculated.
Direct mandibular measurements

These measurements were taken using a digital
calibrator (AMIG T304B.W-1220, AMIG, Amorebieta-Etxano, Spain). The interedges (apicalcoronal distance in mm) were measured perpendicularly from the base of the mandibular body
to the alveolar ridge, along each of the lines
corresponding to the tomographic slices (Fig. 3c).
Statistical analysis

The data were analyzed using SPSS statistical
software (Version 12.0; SPSS, Chicago, Ill., U.S.).
Descriptive statistics were obtained for each variable. The associations between the different
qualitative variables were studied using Pearson’s
chi-squared test. Student’s t-test for two independent samples was applied to quantitative
variables, in each case determining whether variances were homogeneous. Statistical signiﬁcance was set at p ≤ 0.05.

cies were positive in nine (50%) of the slices,
while in the remaining nine (50%), the measurements taken from the CT scans were lower than
the measurements taken from the bone. In six of
the 18 slices analyzed (33.33%), the discrepancies observed showed statistically signiﬁcant
differences (p ≤ 0.05; Table 1).
When the basal plane was used as the axial
reference plane, discrepancies were also found
between measurements taken from tomographic
slices and clinical measurements of the mandibles in all 18 slices analyzed. These discrepancies were negative in all cases. In 17 of the slices
(94.44%), the discrepancies showed statistically signiﬁcant differences (p ≤ 0.05; Table 2).
In this sense, with regard to positioning the
patient when the CT scans were taken, use of the
occlusal plane as axial reference produced the
most accurate measurements (Fig. 4).
When the distribution of discrepancies in
millimeters found in each of the 18 tomographic
slices was compared in relation to the axial reference plane, a higher percentage (99.44%) of
discrepancies greater than 0.5 mm were produced when the basal plane was used than when
the occlusal plane was used (44.44%), with the
difference being statistically significant
(p = 0.001; Table 3).

Results
Discussion
In comparing measurements taken from the 18
tomographic slices of each mandible with measurements taken directly from the bone when the
occlusal plane was used as the axial reference
plane, discrepancies were found in all of the
tomographic slices assessed. These discrepan-

Ever since the ﬁrst dental implants were introduced by Brånemark et al. in 1969, dental practitioners and researchers have sought methods that
might improve the accuracy of surgical implant
placement.21 CT has been widely used for preop-

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Volume 2 | Issue 3/2016 45

Figs. 3a–c
Measurements taken from
the mandibles: (a) radiographic measurement of a
sagittal tomographic slice
using the occlusal plane as
the axial reference plane;
(b) radiographic measurement
of a sagittal tomographic slice
using the basal plane as the
axial reference plane;
(c) bone measurement taken
using a digital calibrator.

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Axial plane in computed tomography

†

Table 1

Sagittal
tomographic
slices

Radiographic
measurements
(n = 39)
Mean ± SD†

Bone measurements
(n = 39)
Mean ± SD

Discrepancies
Mean ± SD

p-value

Cut 1

25.04 ± 4.03

24.96 ± 3.93

0.16 ± 1.33

0.250

Cut 2

25.03 ± 4.11

25.16 ± 3.98

-0.13 ± 1.33

0.085

Cut 3

25.74 ± 4.24

25.98 ± 4.19

-0.24 ± 1.37

0.106

Cut 4

26.82 ± 4.17

27.31 ± 4.05

-0.48 ± 1.45

0.498

Cut 5

28.41 ± 4.35

29.17 ± 4.35

-0.76 ± 1.75

0.389

Cut 6

30.64 ± 4.39

30.61 ± 4.31

0.03 ± 1.39

0.611

Cut 7

31.31 ± 4.31

30.29 ± 4.36

1.02 ± 1.48

< 0.001

Cut 8

31.34 ± 4.57

30.09 ± 4.43

1.24 ± 1.76

< 0.001

Cut 9

31.59 ± 4.77

30.11 ± 4.74

1.47 ± 1.81

< 0.001

Cut 10

31.55 ± 4.84

30.24 ± 4.62

1.31 ± 1.71

< 0.001

Cut 11

31.32 ± 4.64

30.17 ± 4.45

1.15 ± 1.61

< 0.001

Cut 12

30.87 ± 4.53

29.83 ± 4.55

1.03 ± 1.43

< 0.001

Cut 13

29.78 ± 4.63

29.51 ± 4.65

0.27 ± 1.77

0.330

Cut 14

28.13 ± 4.82

28.29 ± 4.91

-0.31 ± 1.87

0.524

Cut 15

26.61 ± 4.75

27.02 ± 4.75

-0.41 ± 1.75

0.345

Cut 16

25.64 ± 4.49

25.94 ± 4.71

-0.29 ± 1.45

0.144

Cut 17

25.21 ± 4.56

25.37 ± 4.78

-0.17 ± 1.31

0.251

Cut 18

25.11 ± 4.38

25.64 ± 4.64

-0.52 ± 1.48

0.500

SD = standard deviation.
Fig. 4

Table 1
Discrepancies between
radiographic measurements
(mm) and measurements
taken directly from the bone
(mm) using the occlusal plane
as the axial reference plane
(Student’s t-test).
Fig. 4
Bar graph comparing
discrepancies between
radiographic measurements
(mm) and measurements
taken directly from the
mandibles (mm) using both
axial reference planes studied.

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Table 2

†

Sagittal
tomographic
slices

Radiographic
measurements
(n = 39)
Mean ± SD†

Bone measurements
(n = 39)
Mean ± SD

Discrepancies
Mean ± SD

p-value

Cut 1

24.53 ± 3.88

24.96 ± 3.93

-0.42 ± 1.11

0.064

Cut 2

24.61 ± 4.02

25.16 ± 3.98

-0.55 ± 1.11

0.001

Cut 3

25.13 ± 4.15

25.98 ± 4.19

-0.84 ± 1.07

< 0.001

Cut 4

26.07 ± 4.08

27.31 ± 4.05

-1.23 ± 1.21

< 0.001

Cut 5

27.71 ± 4.22

29.17 ± 4.35

-1.46 ± 1.26

< 0.001

Cut 6

29.67 ± 4.30

30.61 ± 4.31

-0.92 ± 1.15

< 0.001

Cut 7

29.53 ± 4.21

30.29 ± 4.36

-0.75 ± 1.31

< 0.001

Cut 8

29.38 ± 4.35

30.09 ± 4.43

-0.71 ± 1.16

< 0.001

Cut 9

29.34 ± 4.47

30.11 ± 4.74

-0.77 ± 1.53

< 0.001

Cut 10

29.41 ± 4.55

30.24 ± 4.62

-0.82 ± 1.15

< 0.001

Cut 11

29.25 ± 4.36

30.17 ± 4.45

-0.92 ± 1.18

< 0.001

Cut 12

29.26 ± 4.37

29.83 ± 4.55

-0.56 ± 1.36

0.001

Cut 13

28.67 ± 4.62

29.51 ± 4.65

-0.83 ± 1.13

< 0.001

Cut 14

27.26 ± 4.83

28.29 ± 4.91

-1.03 ± 1.37

< 0.001

Cut 15

26.14 ± 4.89

27.02 ± 4.75

-0.87 ± 1.26

< 0.001

Cut 16

25.14 ± 4.94

25.94 ± 4.71

-0.79 ± 1.46

< 0.001

Cut 17

24.71 ± 4.83

25.37 ± 4.78

-0.66 ± 1.25

0.004

Cut 18

24.73 ± 4.84

25.64 ± 4.64

-0.91 ± 0.41

< 0.001

SD = standard deviation.

Table 2

Table 3

Occlusal plane (n = 18)
n (%)

Basal plane (n = 18)
n (%)

Discrepancies

p-value
0.001

≤ 0.5 mm

10 (55.56)

1 (5.56)

> 0.5 mm

8 (44.44)

17 (94.44)

erative assessment of dental implant treatments.22
It provides good images of the thickness of vestibular cortical bone and interalveolar distances,
as well as of important anatomical features in
jaws.23 When used for imaging the mandible, the
main advantage of CT scans over periapical or
panoramic radiographs is that they provide a
relatively accurate assessment of the alveolar

Table 3

crestal bone height and width and its spatial relationship with the mandibular canal.24 However,
although there is a wide range of dental CT equipment marketed as providing accurate bone data
at a 1:1 scale, several studies have shown discrepancies between the radiographic measurements
taken using CT and clinical measurements taken
directly from the bone.14, 25 In 1996, Covino et al.

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Discrepancies between
radiographic measurements
(mm) and measurements
taken directly from the bone
(mm) using the basal plane as
the axial reference plane
(Student’s t-test).

Volume 2 | Issue 3/2016 47

Distribution of discrepancies
in millimeters observed in
each of the 18 sagittal
tomographic slices in relation
to the axial reference plane
used (Pearson’s chi-squared
test).

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used ten rectangular acrylic blocks (prepared with
titanium–molybdenum alloy) as markers spaced
from 1 to 10 mm, respectively.14 A plastic sphere
was prepared with ten sets of titanium markers
spaced at variable intervals of 1–10 mm. Each object was scanned three times at slice thicknesses
of 3.0 mm and slice thicknesses of 1.5 mm with
0.5 mm overlap, positioned in the CT scanner in
two different positions in relation to the scanning
beam (perpendicular and parallel). The authors
concluded that when CT was carried out with
slices every 3.0 mm, if the procedure was not performed correctly, signiﬁcant errors would occur,
but if the slices were less than 1.5 mm, even if the
CT procedure were performed erroneously to
some extent, the results would not show much
variation and would be more precise. In 2004,
Hanazawa et al. compared data obtained by means
of a modiﬁed CT system and a conventional CT
device with real measurements taken directly from
cadaver mandibles, ﬁnding discrepancies in 90%
of the measurements taken with the modiﬁed CT
system compared with the direct measurements
and in 87.5% of those taken with the conventional CT device, the discrepancies being approximately 1 mm.25
These radiographic discrepancies can lead to
iatrogenic lesions during implant treatment,
which are of particular concern in posterior mandibular regions, where they can produce lesions
of the mandibular canal. In this regard, Klinge et
al., who studied sensitivity and accuracy in locating the mandibular canal using cadaverous
mandibles, observed that when the accuracy in
determining mandibular canal position was
evaluated, comparing the extent of error with the
true value, the error was up to 1 mm in 94% of
the CT measurements, but 39% with tomography, 17% with panoramic radiography and 53%
using intra-oral radiography.23 Similar discrepancies between mandibular canal positions determined radiographically using CT and measurements taken directly from the bone have
been observed by other authors.15, 16, 26
Similarly, numerous authors have observed
small variations between the precision of
three-dimensional preoperative imaging and the
ﬁnal surgical positions of the dental implants,
with variations ranging between 0.7 mm and
1.0 mm,2, 27 due to the discrepancies between CT
measurements and the real dimensions. In this
way, the results of the present study, in which
discrepancies varied between 0.03 mm and
1.47 mm, coincide with the discrepancies observed by these authors.
48 Volume 2 | Issue 3/2016

Acquiring a good CT scan is of primary importance for visualizing the different bony structures,
and the quality and accuracy of the scan are inﬂuenced by various factors. The skill of the operator has a major inﬂuence. Adequate positioning of the patient will minimize error, and the
choice of the appropriate equipment settings is
important for achieving good contrast. Discrepancies between radiographic and real measurements can increase according to patient positioning for CT scanning.17, 18 However, although many
authors have observed discrepancies between
radiographic measurements using CT and real
bone measurements, these authors used a single
axial reference plane, which in many cases was
not speciﬁed.28–31 Currently, there are very few
articles that examine the discrepancies obtained
with various axial reference planes. Cucchiarelli
et al.’s comparison of the discrepancies between
radiographic measurements with CT and measurements taken directly from 15 edentulous
maxillae showed distortions with regard to the
real bone measurements.19 It was found that the
use of the horizontal plane showed 19.20% magniﬁcation, as opposed to the use of the occlusal
plane, which showed 16.5% magniﬁcation. In this
regard, Abrahams made a general study of mandibles using CT and concluded that the best axial reference plane is the occlusal plane.32 Although the present study found discrepancies
when both the occlusal plane and the basal plane
were taken as the axial reference plane, the discrepancies were greater when the basal plane
was used.

Conclusion
The present study found that there are slight discrepancies between radiographic measurements
taken using CT and real bone measurement. These
must be taken into consideration in order to perform satisfactory implant treatments. With regard
to patient positioning for the CT procedure, use of
the occlusal plane as axial reference will produce
the most accurate measurements.

Competing interests
We wish to conﬁrm that there are no known conﬂicts of interest associated with this publication
and there has been no signiﬁcant ﬁnancial support for this work that may have inﬂuenced its
outcome.

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Acknowledgments
We wish to acknowledge the contribution of the
radiology unit of Virgen de la Arrixaca Hospital,
Murcia, Spain.

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Immediate loading using guided surgery

Immediate loading of variable-thread
expanding tapered-body implants placed
into maxillary post-extraction or healed
sites using a guided surgery approach:
An up-to-five-year retrospective analysis
Abstract
Objective
Giovanni Polizzi,a Tommaso Cantoni,a Emanuele Pasinia
& Marco Tallaricob
a
b

Private Clinic BSC, Verona, Italy
Dentistry Unit, University Hospital of Sassari, Sassari,
Italy

Corresponding author:
Dr. Giovanni Polizzi
Private Clinic BSC
Via Gobetti 9
37138 Verona
Italy

Transitioning from failing dentition to complete-arch implant rehabilitation
may involve temporarily rendering the patient edentulous. In order to avoid
the use of a removable prosthesis, immediate implant placement and immediate loading with a ﬁxed provisional prosthesis have been proposed.
The aim of this study was to retrospectively assess the clinical and radiographic performance of variable-thread expanding tapered-body implants
placed into maxillary post-extraction or healed sites using computerassisted template-guided surgery with a specially designed radiographic stent.
Materials and methods

giovanni.polizzi@bscvr.com
This paper was presented at the European
Association for Osseointegration annual meeting
in Rome, Italy, on Sept. 25th, 2014.

Data from 160 implants placed in 27 consecutive patients were evaluated
up to ﬁve years (mean of 29 months). Outcomes were implant and prosthetic survival and success rates, biological and mechanical complications,
marginal bone remodeling, sulcus bleeding index, plaque score and gingival index.
Results

How to cite this article:
Polizzi G, Cantoni T, Pasini E, Tallarico M. Immediate loading
of variable-thread expanding tapered-body implants placed
into maxillary post-extraction or healed sites using a guided
surgery approach: an up-to-5-year retrospective analysis.
J Oral Science Rehabilitation.
2016 Sep;2(3):50–60.

At the last follow-up, one implant had failed, resulting in an overall implant
cumulative survival rate of 99.4%, and all of the prostheses were in situ.
Marginal bone remodeling was statistically signiﬁcantly higher in the
healed sites (-0.67 ± 0.97 mm; n = 105) than in the post-extraction sites
(0.42 ± 0.99 mm; n = 55; p = 0.026). Two implants showed excessive
marginal bone remodeling (> 3 mm) at the last follow-up (1.25%). Good
soft-tissue parameters were found around all of the other implants.
Conclusion

The expanding tapered-body implants placed into healed and postextraction maxillary sites using computer-assisted template-guided surgery and immediately loaded showed a good survival rate and good periodontal parameters.
Keywords

Immediate loading, tapered-body implant, guided surgery.
50 Volume 2 | Issue 3/2016

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Introduction
Transitioning from a failing dentition to completearch implant rehabilitation may involve temporarily rendering the patient edentulous.1 In such
cases, interim complete removable dental prostheses have been used after extraction of the
hopeless teeth and during the osseointegration
period. However, many patients object to a complete removable dental prosthesis for psychological, functional or esthetic reasons, and request
ﬁxed provisionalization throughout all phases of
the rehabilitation process.2, 3 In order to avoid the
use of a removable prosthesis, immediate implant
placement and immediate loading with a ﬁxed
interim prosthesis have been proposed for the
rehabilitation of hopeless dentition.4 Indeed, immediately loaded implants placed into postextraction sockets have recently been demonstrated to provide a reliable option for replacing
failing residual teeth.5 Although immediate loading may place implants at a higher risk of complications,6 comparable survival rates have been
reported for the two loading protocols.7 Furthermore, immediate loading combined with implant
placement in post-extraction sites may result in
improved esthetic outcomes owing to preservation of osseous and gingival architecture, offer
reduced treatment time, and provide the patient
with the convenience of an immediate tooth replacement.8 The risk of implant failure can be
minimized by proper patient selection, welltrained operators, high primary implant stability
and lack of micromovements.9
Computer-aided design (CAD) technology allows for the transfer of patient data to a 3-D implant planning program for virtual implant placement.10 The virtual planning is then used to
generate a custom-made surgical template (computer-aided manufacturing—CAM) with metallic
sleeves to precisely guide each dental implant into
the position planned virtually. In addition, implant-supported ﬁxed acrylic resin prostheses can
be fabricated in advance and immediately delivered to the patient. These aspects of minimally
invasive and simpliﬁed surgery, along with reducing the treatment time and postoperative discomfort, are beneﬁcial to the patient.11 Favorable
clinical results of computer-assisted template-guided surgery have been shown in several
studies;12–15 however, deviations in 3-D position
between virtual planning and actual ﬁnal position
of the implant in the patient’s jaw and techniquerelated perioperative complications have to be
taken into account.16–20

In 2009, Cantoni and Polizzi described a step-bystep technique involving a specially designed
two-piece radiographic stent that allows the
patient to retain hopeless teeth until the day of
the surgery, making easier the transition from
failing dentition to implant-supported prostheses.21 The present study aimed to retrospectively assess the survival rate of variable-thread
expanding tapered-body implants (NobelActive,
Nobel Biocare, Zurich, Switzerland) placed into
maxillary post-extraction or healed sites using
template-guided surgery in combination with a
specially designed radiographic stent.21 This
study followed the Strengthening the Reporting
of Observational Studies in Epidemiology guidelines.22

Materials and methods
This retrospective study evaluated data collected
from 27 consecutive patients of both sexes (19
females, 8 males), aged 18 years or older (range of
38–84; mean of 60.6), presenting with failing
maxillary dentition, confirmed by clinical and
radiographic examination, and with a preference
for a complete-arch implant-supported ﬁxed dental prosthesis or an intolerance to a complete removable dental prosthesis. All of the implants were
placed without elevation of a ﬂap in maxillary
post-extraction sockets or healed sites using computer-assisted template-guided surgery (NobelGuide, Nobel Biocare) between September 2009
and October 2012. The patients were clinically
followed for a minimum of two years (range of two
to ﬁve years; mean of 29 months). All of the patients were treated in a single specialized implant
rehabilitation center. Two clinicians performed all
of the surgical (GP) and prosthetic (TC) procedures,
and two dental laboratories manufactured all of
the restorations. One independent examiner (EP)
conducted a retrospective chart analysis of the 27
consecutively implanted patients with compromised dentition in the maxilla.
Patients were informed about the clinical procedures, materials to be used, beneﬁts, potential
risks and complications, as well as follow-up
evaluations required for the clinical trial, and gave
their written consent to take part in this study. All
of the procedures were conducted in accordance
with the Declaration of Helsinki of 1975 for biomedical research involving human subjects, as
amended in 2008. The patients were not admitted
to the study if any of the following exclusion criteria were present: general contraindications to

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Fig. 1

Fig. 1
Initial clinical situation of a
female patient with hopeless
teeth in the maxilla.
Figs. 2a & b
Initial radiographic situation
of a female patient with
hopeless teeth in the maxilla.

Figs. 2a & b

a

b

implant surgery; subjected to irradiation in the
head and neck area less than one year before implantation; untreated periodontitis; poor oral hygiene and motivation; uncontrolled diabetes;
pregnant or nursing; substance abuse; psychiatric problems or unrealistic expectations; severe
bruxism or clenching; immunosuppressed or immunocompromised; treated or under treatment
with intravenous amino-bisphosphonates; lack
of opposite occluding dentition or prosthesis in
the area intended for implant placement;
active infection or severe inﬂammation in the area
intended for implant placement; and need of bone
augmentation procedures at implant placement.
52 Volume 2 | Issue 3/2016

Diagnostic protocol

The patients’ medical histories were recorded and
preoperative photographs (Fig. 1) and radiographs, including periapical (Figs. 2a & b) and
panoramic radiographs, were obtained for initial
screening and evaluation. Before implant placement, all of the patients underwent a cone beam
computed tomography (CBCT) scan (New Tom
VGi, Quantitative Radiology, Verona, Italy) according to a double-scan protocol.10 A two-piece
radiographic guide was used for the diagnostic
study and the virtual implant planning according
to previously described procedures (Fig. 3).21 In

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Fig. 3

Fig. 3
Two-piece radiographic stent
used for the CBCT scan.
Figs. 4a & b
Implant planning with teeth
still in place. (a) Occlusal view.
(b) Cross-sectional image.

Figs. 4a & b

a

b

order to predictably obtain a surgical template
with the same ﬁtting dimensions as the originally scanned radiographic guide, the NobelGuide
calibration procedure was performed for each
patient according to the manufacturer’s instructions, using a speciﬁc calibration object. Finally,
the two data sets were converted with the
NobelGuide software to preview the patient’s
anatomy and to plan treatment (Figs. 4a & b).
Once planning had been completed, the surgical
template was ordered.

Surgical and prosthetic protocols

Antimicrobial prophylaxis with amoxicillin 1 g
(Zimox, Pfizer, Rome, Italy) or clindamycin
600 mg, if allergic to penicillin, was administered b.i.d. for six days, starting 2 h before surgery. Prior to the start of surgery, patients rinsed
with a 0.2% chlorhexidine mouthwash for 1 min.
Oral premedication with ﬂurazepam monohydrochloride 15 mg (Flunox, Teofarma, Pavia,
Italy), octatropine methyl bromide 40 mg and

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Fig. 5a

a
Fig. 5b

Figs. 5a & b
Clinical situation after implant
treatment at ﬁve years of
follow-up. (a) Frontal view.
(b) Lateral view.

diazepam 5 mg (Valpinax, Crinos, Milan, Italy)
was given prior to surgery. Local anesthesia was
induced by inﬁltration of the buccal and palatal
regions of the surgical area with a 4% articaine
solution with 1:200,000 epinephrine (Ubistesin, 3M Italia, Bergamo, Italy). Conscious sedation with midazolam 0.05–0.15 mg/kg IV
(Ipnovel, Roche, Monza, Italy) was performed;
ranitidine 100 mg IV (Ranidil, Menarini, Florence, Italy) and ondansetron 4 mg IV (Zofran,
GlaxoSmithKline, Brentford, U.K.) were also
administered for gastroprotection and prevention of nausea and vomiting. A single postoperative dose of dexamethasone 8 mg IV
(Decadron, Visufarma, Rome, Italy) and ketorolac 30 mg IV (Toradol, Recordat, Rome, Italy)
was also given.
54 Volume 2 | Issue 3/2016

Hopeless teeth were atraumatically extracted
with the aid of a periotome (PT2, Hu-Friedy,
Chicago, Ill., U.S.) and the sockets debrided. In
cases of multiple-rooted teeth, a rhizotomy was
performed, starting from the center of the tooth,
followed by careful extraction of the individual
roots to prevent damage to the alveolar walls.
Upon completion of the extraction, the integrity,
depth and inclination of the alveolar socket were
checked with a periodontal probe. The surgical
templates were positioned using the silicone
surgical index derived from the mounted casts,
and precise ﬁt was visually and manually assessed. The surgical template was then stabilized with three to ﬁve preplanned anchor pins.
All of the implants were placed through metallic
sleeves in a fully guided surgery approach. Im-

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Figs. 6a & b

Fig. 6c

Figs. 6a–c
Radiographic situation
after implant treatment at
ﬁve years of follow-up.

plant sites were prepared according to the manufacturer’s guidelines. Furthermore, a guided
screw tapping was performed for half the depth
of the osteotomy site, in order to provide an accurate and passive pressure-free seating of the
implant into the prepared osteotomy. The bone
tap was performed as the last step immediately prior to implant placement. Care was taken
not to overheat the bone during the tapping
procedure. The bone taps were removed from
the site through counterclockwise rotation. Both
tapping and implant placement were performed
at 20 rpm. In the healed sites, the implant platform was positioned at the bone level, while in
immediate post-extraction sockets, the platform
was placed 1 mm deeper, below the buccal
bone crest, engaging at least 3 mm of the bone
apical to the root apex to achieve adequate
primary stability of at least 35 N cm (range of
35–70 N cm; mean and standard deviation of
57.1 ± 13.4 N cm).
The residual gap between the buccal bone
plate and the implant surface was ﬁlled with a
mixture of autogenous bone and freeze-dried
deproteinized bovine bone (Geistlich Bio-Oss,

Geistlich Pharma, Wolhusen, Switzerland). In
extraction sockets presenting severe buccal
bone dehiscence, the socket was sealed with a
collagen membrane (Geistlich Bio-Gide, Geistlich Pharma) or with a connective tissue graft
and left to heal without implant placement.
All of the implants were immediately loaded
with a metal-reinforced, screw-retained acrylic
resin provisional restoration without any cantilever. All of the restorations were prefabricated
on a master cast poured from the surgical template, with the implant replica on-site. Nonengaging titanium temporary abutments were
connected at the implant or abutment level. The
provisional restoration was placed in the mouth
and assessed for passive ﬁt around the abutments. If any tension was detected, more space
was provided by adjusting the provisional restoration. Once the prosthesis had been completely
seated, a preliminary occlusal adjustment was
performed. Using a disposable syringe ﬁlled with
a cold-cure acrylic resin, the abutments were
then connected to the temporary restoration by
injecting the resin into the space between the
abutments and the framework, having the pa-

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tient close into occlusion. When the cold-cure
acrylic resin had fully set, the provisional restoration was unscrewed from the mouth. The restoration was then reﬁned, polished and screwed
into the patient’s mouth approximately 2–3 h
later. A ﬁnal check of the occlusion and of the
interproximal spaces was then performed. The
screw access holes were closed with PTFE and
temporary ﬁlling material. Periapical radiographs of all of the implants were then obtained.
All of the patients received postoperative instructions and prescriptions. In addition, an oral
antiseptic and soft brushing were recommended for the ﬁrst two weeks. Patients were recalled
for clinical (Figs. 5a & b) and radiographic
(Figs. 6a–c) examination and oral hygiene
checks at two and four weeks, three, six and 12
months, and then yearly up to ﬁve years after
implant placement. On average, the provisional
fixed restorations were removed after six
months and replaced with titanium or zirconia
CAD/CAM screw-retained prostheses, with
acrylic or ceramic esthetic material.
Outcomes

The primary outcomes were implant and prosthetic survival and success rates assessed 15
days after prosthesis delivery and then yearly
up to ﬁve years after surgery, according to Papaspyridakos et al.23 This investigation’s prosthetic survival and success rates were deﬁned
as follows: a successful implant-supported dental prosthesis was a prosthesis that remained in
function and the esthetic evaluation of which by
both the dentist and patient was satisfactory at
delivery and during the study period; a surviving
implant-supported dental prosthesis was a prosthesis that remained in function even though
not all success criteria were fulﬁlled and any
discrepancies were regarded as correctable; and
a failed implant-supported dental prosthesis
was a prosthesis that had been removed, fractured beyond repair, or could not be classiﬁed
as a successful or surviving dental prosthesis.
The secondary outcomes were any biological
(pain, swelling, suppuration, etc.) and/or mechanical complications (fracture of the framework
and/or the veneering material, screw loosening,
etc.) occurring during the entire follow-up period,
marginal bone level (MBL) changes, and periodontal parameters.
The distance from the most coronal margin
of the implant collar to the most coronal point of
bone-to-implant contact was defined as the
56 Volume 2 | Issue 3/2016

MBL. The MBL around the implants was evaluated on intra-oral digital radiographs taken with
the paralleling technique using a film-holder
(Rinn XCP, DENTSPLY, Elgin, Ill., U.S.) at implant
placement (baseline) and then annually. The
radiographs were accepted or rejected for evaluation based on the visibility of the implant
threads. All readable radiographs were displayed
in an image analysis program (Scion Image 4.0.2
for Windows, Scion Corporation, Frederick, Md.,
U.S.) on a 24-in. LCD screen (iMac, Apple, Cupertino, Calif., U.S.) and evaluated under standardized conditions (according to ISO 12646:2004).
The software was calibrated for each image using
the implant diameter. Measurements of the
mesial and distal bone crest level adjacent to each
implant were made, with accuracy of 0.01 mm,
and averaged at the implant level. Marginal bone
remodeling was calculated as the difference between the reading at the follow-up examination
and the baseline value. Three groups were created in order to avoid bias in marginal bone remodeling: all implants, implants placed into postextraction sites and implants placed into healed
sites.
Periodontal parameters around the implants
were assessed at the last follow-up examination.
The sulcus bleeding index was assessed using a
plastic periodontal probe (Plast-o-Probe, DENTSPLY Maillefer, Ballaigues, Switzerland) at four
sites around each implant (mesial, distal, buccal
and lingual), according to the Mombelli Index,24
and was reported at the implant level. The plaque
score was recorded using a plastic periodontal
probe (Plast-o-Probe) and defined as the
presence of plaque (yes/no) on the abutment–
restoration complex. The gingival index was deﬁned as follows: 0 = normal gingiva; 1 = mild
inﬂammation, slight change in color, slight edema, and no bleeding on probing; 2 = moderate
inﬂammation, redness, edema, glazing, and bleeding on probing; and 3 = severe inﬂammation,
marked redness and edema, ulceration and tendency to spontaneous bleeding.
Implant and prosthetic survival and success
rates were evaluated by an independent dentist
(EP). Complications were assessed and treated
by a nonblinded treating clinician (GP). The marginal bone remodeling was evaluated by an independent radiologist. An independent blinded
dental hygienist who was not involved in the
study performed all of the periodontal measurements.

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cluded in the statistical analysis. Only one postextraction implant failed in one patient, who showed poor oral hygiene, during the second year,
and showed clinical signs of mobility and infection, resulting in an overall implant CSR of 99.4%.
The life table analysis is summarized in Table 1.
All prostheses were in situ at the last follow-up,
accounting for a cumulative prosthetic survival
rate of 100% up to ﬁve years after insertion.
Two implants (1.25%) showed marginal bone
remodeling of greater than 3 mm at the last
follow-up. However, none of the implants presented with an exposed implant neck, and no
surgical intervention was performed. All of the
affected patients underwent nonsurgical therapy
consisting of manual debridement using titanium
curettes and a glycine-based air–powder abrasive device, and local application of antimicrobial agents (minocycline HCl 1 mg, Arestin, OraPharma, Horsham, Pa., U.S.), followed by oral
hygiene instructions and motivation, together
with a strict follow-up protocol. At the subsequent follow-ups, the bone recession had stopped and the soft tissue remained stable. No other
biological or mechanical complications occurred
during the entire follow-up period, resulting in a
cumulative implant and prosthetic success rate
of 97.9%.
At the last follow-up (mean of 29 months), the
marginal bone remodeling was -0.58 ± 0.98 mm.
Implants placed into post-extraction sockets
(0.42 ± 0.99 mm) showed statistically lower marginal bone remodeling compared with implants
placed into healed sites (-0.67 ± 0.97 mm;
P = 0.026).
At the last follow-up session, bleeding after
careful insertion of a periodontal probe 1 mm into
the mucosal sulcus parallel to the abutment surface was detected around three implants (1.6%).

Statistical analysis

Statistical analysis was performed using SPSS
for Windows (Version 18.0; SPSS, Chicago, Ill.,
U.S.). Descriptive analysis was performed using
mean, standard deviation and frequency distribution. A life table analysis of implant cumulative
survival rates (CSRs) was calculated. Kaplan–
Meier survival analysis was performed to allow
estimation of survival over time, even when patients dropped out or were followed for different
lengths of time. The Wilcoxon signed-rank test
for paired data was utilized to compare overall
bone levels between baseline (implant placement) and follow-ups in both healed and postextraction sites, and to compare bone remodeling
between post-extraction and healed sites at the
last follow-up examination. The implant was
used as the statistical unit of the analysis. All
statistical comparisons were conducted at the
0.05 level of signiﬁcance.

Results
All 27 selected and analyzed patients met the inclusion criteria. Patients received a total of 160
NobelActive implants (22 narrow diameter, 106
regular diameter and 32 wide diameter) with a
moderately rough surface (highly crystalline and
phosphate-enriched titanium oxide). One hundred
and ﬁve implants were placed into healed sites
and 55 into post-extraction sockets. Each patient
received at least one post-extraction implant.
Patients were clinically followed for up to ﬁve
years.
At the last follow-up, no patients had dropped
out and no deviation from the original protocol
had occurred. All of the collected data were inTable 1

Table 1

Period (years)

Surviving
implants

Failed implants

Not followed

CSR (%)

0–1

160

100.0

1–2

160

100.0

2–3

160

99.4

3–4

148

99.4

4–5

100

99.4

–

99.4

†

* According to the last recorded patient follow-up.
†
Cumulative survival rate.

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Life table analysis of all
surviving implants.*

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Twelve patients with 68 implants showed a slight
amount of plaque around the implant–abutment
interface; thus, the overall plaque score was
36.0% and 44.4% at implant and patient level,
respectively. The gingival index was reported as
90.5% normal gingiva, 7.9% with mild inﬂammation and 1.6% with moderate inﬂammation.

Discussion
This study retrospectively evaluated the success
and survival rates of variable-thread tapered-body
implants placed into post-extraction or healed
sites in the maxilla using computer-assisted template-guided surgery in combination with a specially designed two-piece radiographic stent.21
The main limitations of this study are its
retrospective nature, which may have limited the
data collection, and the analysis of possible
variables (soft-tissue thickness, time of placement or loading) that may have inﬂuenced the
bone resorption. Another limitation is the limited
number of participants. However, this investigation may be considered as a pilot study for future
multicenter randomized controlled trials with
sample size calculation and multivariate analysis.
Implants placed into post-extraction sockets
showed lower marginal bone remodeling than
implants placed into healed sites did; thus, the
null hypothesis that there is no difference between the two protocols in terms of hard-tissue
response has to be rejected.
In the present study, one out of 160 implants
failed over a period of ﬁve years, accounting for
an overall implant CSR of 99.4%. The major
clinical conclusion of this retrospective study is
that immediate post-extraction placement of
implants and immediate provisionalization may
be considered an effective and reliable treatment
option for patients who would prefer to have a
shortened overall treatment time and to be rehabilitated immediately with the aid of computerassisted template-guided surgery.
Proper patient selection and well-trained
operators are necessary to minimize the risk of
implant failure. Immediate implant placement
and provisionalization in both post-extraction
sockets and healed sites are technically demanding procedures, and the surgical and prosthetic
skills required are superior to those necessary for
conventional implant treatment.
To the best of our knowledge at the time of
writing this article, there were no other published

58 Volume 2 | Issue 3/2016

studies that evaluated the use of a variable-thread
tapered-body implant with internal conical
connection, in-built platform shifting and a moderately rough oxidized surface in combination
with computer-assisted template-guided surgery to treat failing dentition in the maxilla. For
this reason, it is difficult to evaluate how the
present results ﬁt with other comparable studies.
However, there is a randomized controlled trial
that investigated the same implant design that
may provide some comparable data.25
The marginal bone remodeling reported in
the present study, measured from implant placement until the last follow-up examination, was
-0.58 ± 0.98 mm. This value is slightly lower than
the data reported in the literature for two-piece
implants, for which after the initial bone loss
during the first year post-placement, about
0.1–0.2 mm of crestal bone loss was found at the
annual follow-up.26, 27 Pozzi et al. recently published three-year results of a randomized controlled
trial, reporting a marginal bone remodeling of
0.83 ± 0.27 mm around NobelActive implants
placed into healed sites in the posterior mandible.25 One reason for these differences may be
that surgeons operating freehand tend to elevate wider ﬂaps to better visualize the area in
which the implants are to be placed. With dedicated template-guided implant placement, wider
ﬂaps were in many cases considered unnecessary, since the surgeons were able to rely on the
surgical template.11 Another explanation that may
account for the differences in the observed MBL
changes is that, in some of the aforementioned
studies, all of the implants were placed into
healed sites.11, 25 In the present study, statistical
analysis showed a statistically signiﬁcant difference (P = 0.026) in mean marginal bone remodeling at the last follow-up between implants placed into healed sites (-0.67 ± 0.97 mm)
and those placed into post-extraction sites
(0.42 ± 0.99 mm). These ﬁndings are in accordance with a recent systematic review and meta-analysis on the alterations of the bone dimension after immediate implant placement into
extraction sockets.28
In the present study, the diagnostic protocol
included the calibration procedure of the digital
workflow for each patient, according to the
manufacturer’s instructions. Scanning physical
objects like the radiographic guide requires an
optimized workﬂow, because the data are converted into 3-D models, which are used not only
for diagnostic purposes but also for physical pro-

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duction. Since the data are digitized using X-ray
technology and since material properties or densities are visualized through various kinds of gray
value shades, the workﬂow is highly dependent
on the gray values assigned to the scanned 3-D
data from the DICOM ﬁles. More precisely, the
workﬂow is dependent on the actual gray value
that deﬁnes the radiographic guide’s borders.
This gray value assignment to the DICOM ﬁles is
unfortunately not standardized for CBCT scanners (almost every scanner assigns different gray
values to different objects and materials), making
reliable default values for each scanner model
almost impossible. This ultimately has implications regarding the produced dimensions of the
surgical template, as these dimensions are deﬁned by the gray value selection representing the
borders of the scanned radiographic guide. In
order to automatically detect and automatically
apply the correct settings needed for the software to deﬁne the actual physical borders of the
scanned radiographic guide, NobelClinician
(Nobel Biocare) is designed to work with the
unique and innovative NobelGuide calibration
procedure. The calibration object is a highprecision object, milled from a material that behaves the same way when penetrated by X-rays
as the resins typically used for the radiographic
guide in combination with the scanner. This process ensures that each time the CBCT scanner is
used with a known scanner the surgical template produced will have the same ﬁtting dimensions
as the originally scanned radiographic guide. As
a result, the procedure does not calibrate the
scanner, but calibrates the full workﬂow, from
an accurately ﬁtting radiographic guide to an
accurately ﬁtting surgical template.
Many factors are likely to affect the success
of immediately loaded implants, including bone
quality and quantity, the skill and experience of
the clinician, implant design, implant primary
stability, micro- and macromovement, as well as
occlusion. The quality and quantity of bone at the
implant site have been shown to be important in
determining the success of dental implants and
are critical for ensuring the initial stability of the
implant upon insertion.29 Primary implant stability and lack of micromovement are considered to
be two of the main factors necessary for achieving predictable high success rates for osseointegrated oral implants.30 Thus, a high insertion
torque value appears to be one of the prerequisites for a successful immediate or early loading
procedure. The variable-thread tapered implant

design with a moderately rough surface was introduced into the market to facilitate one-stage
surgical procedures and to allow for immediate
placement and anticipated loading protocols.31
According to the results of the present study, in
which all of the patients included had failing
maxillary dentition and refused interim complete removable dental prostheses, the major indication for such implants is medium- or lowdensity bone sites in the maxilla. Nevertheless,
a slight modiﬁcation of the original drilling protocol was adopted in that implant sites were
underprepared according to the bone density.
However, a guided screw tapping for half the
depth of the osteotomy site was performed immediately before the implant placement. Great
care was taken to ensure optimal accuracy during
implant placement because the implant mount
had a smaller diameter than that of the sleeve.
Nevertheless, this feature allowed the clinician
to perceive the implant stability within the bone,
without any friction between the implant mount
and the sleeve.

Conclusion
Within the limitations of this retrospective study,
variable-thread tapered design implants placed
using computer-assisted template-guided surgery, in combination with a specially designed
two-piece radiographic stent, can be considered
a successful treatment option for immediate implant placement and loading in the maxillae of
completely edentulous patients, based on the
results of up to ﬁve years of follow-up. Postextraction implants showed statistically lower
marginal bone remodeling compared with implants placed into healed sites. The results should
be interpreted with care and data should be
investigated further in randomized controlled
clinical trials.

Competing interests
The authors declare that they have no competing
interests related to this study. No ﬁnancial support was received for this study.

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[62] => JOSR_A4_Editorial_03.qxp_Layout 1

in vitro study on viscosity

An in vitro study on
viscosity using an
electromagnetically spinning
sphere viscometer

Abstract
Objective
Atsuko Imai,a, b Shunsuke Baba,b Keiji Sakai,c
Nami Kurauchi,d Masanori Yasudad & Masahiro Tanakaa
a

Department of Fixed Prosthodontics and Occlusion,
Osaka Dental University, Hirakata, Osaka, Japan
b
Department of Oral Implantology,
Osaka Dental University, Hirakata, Osaka, Japan
c
Institute of Industrial Science, University of Tokyo,
Tokyo, Japan
d
Kyoto Electronics Manufacturing, Kyoto, Japan

The purpose of this study was to investigate the reproducibility of measurements of salivary viscosity using an electromagnetically spinning (EMS)
viscometer.
Materials and methods

An EMS viscometer was used to measure viscosity. A viscosity standard
ﬂuid and artiﬁcial saliva (Saliveht) were used.

Corresponding author:

Results

Dr. Atsuko Imai
atsuko.y.i@gmail.com
How to cite this article:
Imai A, Baba S, Sakai K, Kurauchi N, Yasuda M, Tanaka M. An
in vitro study on viscosity using an electromagnetically
spinning sphere viscometer. J Oral Science Rehabilitation.
2016 Sep;2(3):62–7.

Viscosities of 20.14 mPa s (SD ± 0.04) and 4.26 mPa s (SD ± 0.08) were
recorded for the standard ﬂuid and Saliveht, respectively. These values
did not substantially differ when the measurements were repeated ﬁve
times at different time points and when using different sets of tubes,
spheres and viscosity standard ﬂuids, as well as various amounts of the
ﬂuids.
Conclusion

The use of a newly developed EMS viscometer demonstrated high reproducibility. This device might make chairside measurement of salivary
viscosity simple.
Keywords

Salivary viscosity, electromagnetically spinning sphere viscometer.
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in vitro study on viscosity

Introduction
Saliva is mainly secreted by the three major salivary glands: the parotid, submandibular and
sublingual glands. The saliva secreted from all
three glands mixes in the oral cavity and exerts
physiological functions. Saliva has important
bacteriological, biochemical, and physical effects
on the inside of the mouth, and is relevant to
studies in many different ﬁelds.
In particular, the viscosity of saliva is mainly
responsible for the lubricating action that aids
in the movement of the tongue and lips. It is also
essential for ingestion, swallowing, speech and
other functions.1 Salivary viscosity is correlated
with periodontal disease,2, 3 dental caries4, 5 and
xerostomia,6 and plays a role in the maintenance and stability of dentures;7–9 therefore, it is
an important research topic. Various rotational
viscometers and capillary viscometers have
been used to measure salivary viscosity, but they
are not easy to use and require large amounts
of saliva.10–17
The electromagnetically spinning (EMS) viscometer, developed by Sakai et al. in 2008,18 uses
a minute metal sphere of approximately 2 mm
in diameter submerged in a sealed sample and
subjected to electromagnetic induction, which
is a remote operation that applies rotational
torque. In this new system, the viscoelasticity of
a substance is assessed by a camera that records
the rotational movement of this sphere. This
method uses disposable tubes and spheres, preventing the possibility of infection. The use of
this device might make the chairside measurement of salivary viscosity simple.
To the best of our knowledge, no report has
examined the reproducibility of this device. The
aim of the present study was to evaluate the
reproducibility of measurements of salivary viscosity using an EMS viscometer.

temperature of the viscosity standard ﬂuid had
stabilized, measurements were taken. All measurements were repeated ﬁve times at 30 min
intervals within the same day using the same set
of tubes, spheres and viscosity standard ﬂuid.
We prepared ﬁve different sets of test tubes,
spheres and viscosity reference solutions. A
300 μL aliquot of viscosity reference solution was
added to the device, and ﬁve measurements were
taken after the temperature of the solution had
stabilized. This procedure was then repeated
using various amounts of viscosity standard ﬂuid
(300 μL, 500 μL, 750 μL and 1,000 μL) placed
into different test tubes with different spheres,
and these spheres were then inserted into the
device. Measurements were repeated ﬁve times
within the same day.
Reproducibility with a
low-viscosity solution, Saliveht

A solution of 100% Saliveht (Teijin, Osaka, Japan)
was used as test. The thermostatic bath inside
the device was set at 36 °C and the rotational
speed was set at 1,000 rpm.
The Saliveht (300 μL) was placed into a test
tube and the sphere was immersed in the solution. The tube was then capped with a sealing
cap and inserted into the device. Once the temperature inside the device had stabilized, the
measurements were repeated ﬁve times every
30 min using the same sample, the same test
tube and the same sphere on the same day.
The procedure was then repeated using different ﬁve sets of tubes, spheres and Saliveht
(300 μL), and the measurements were repeated
ﬁve times within the same day. This procedure
was then repeated using various amounts of Saliveht (300 μL, 500 μL, 750 μL and 1,000 μL)
placed into different test tubes with different
spheres, and these spheres were then inserted
into the device.

Materials and methods

Statistical analysis

An EMS viscometer (Kyoto Electronics Manufacturing, Kyoto, Japan) was used to measure viscosity (Fig. 1). An amount of 300 μL of a viscosity standard ﬂuid (Showa Essential Oils, Tokyo,
Japan) was poured into the test tube, the sphere
submerged, and the test tube covered with a
sealed cap and inserted into the device. The
thermostatic bath in the device was set to 36 °C
and a rotational speed of 1,000 rpm. Once the

The mean and standard deviation were calculated
for the data obtained.

Results
Using the same viscosity standard ﬂuid, test tube
and sphere, the results of the ﬁve repeated measurements within the same day showed mean and

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in vitro study on viscosity

Figs. 1a–d

a

b

c

Figs. 1a–d
(a) Electromagnetically
spinning sphere viscometer.
(b) A glass tube.
(c) An aluminum sphere.
(d) A schematic of the
measurement method.

d

standard deviation values of 20.04 mPa s
(SD ± 0.04) (Fig. 2). When different disposable
test tubes and spheres were used, the calculated
mean and standard deviation values were 20.14
mPa s (SD ± 0.04) (Fig. 3). These values were similar to the previous ones. The measurements of the
viscosity using different amounts of ﬂuid showed
no differences between the ﬁve samples. The calculated mean and standard deviation values were
20.12 mPa s (SD ± 0.06) (Fig. 4).

measurements on the same day resulted in mean
and standard deviation values of 4.26 mPa s
(SD ± 0.08), with no differences between the ﬁve
measurements (Fig. 6). Using different amounts
of the test solution resulted in mean and standard
deviation values of 4.04 mPa s (SD ± 0.08), and
no differences were noted with different amounts
of solution (Fig. 7).

Discussion
Reproducibility with Saliveht

The ﬁve measurements taken on the same day
with the same tube and sphere using Saliveht separated by a 30 min interval were quite similar and
yielded mean and standard deviation values of
4.02 mPa s (SD ± 0.06) (Fig. 5). Using different
test tubes, spheres and Saliveht to obtain ﬁve
64 Volume 2 | Issue 3/2016

Saliva aids in maintaining healthy dentition
throughout one’s life and is important for oral
health. Saliva contributes to numerous functions
in the oral cavity, such as speech and swallowing
of foods, maintenance of oral health, protection
of the mucosa from bacterial attack and fungal
growth, prevention of demineralization of the

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in vitro study on viscosity

Figs. 2 & 3

Figs. 4 & 5

teeth and lubrication of the oral cavity. Salivary
viscosity is associated with the amount of mucin;
both these factors are also associated with the
degree of periodontal disease and clinical symptoms.2 The physical properties of saliva, including
ﬂow, pH, buffering capacity, and viscosity, have
been found to be associated with caries activity
in children and to act as markers of caries.5 Xerostomia patients are known to have low salivary
ﬂow and high viscosity compared with healthy
individuals.6 For the maintenance of a complete
denture, the physical properties of saliva between
the base of the denture and the mucosa under
the base are considered important, and thus there
are many studies on the viscosity of saliva and
maintenance of dentures.7 Determining the
amount and condition of saliva at the chairside
with ease is important for improvement of oral
function and the intra-oral environment, eating
and swallowing support, and increased quality
of life.
Viscosity has previously been measured using
capillary ﬂow methods or rotational viscometry.17
Capillary ﬂow methods are simple to operate,

require a short measurement time and are accurate. However, when the viscosity of a non-Newtonian ﬂuid is measured, only the mean value is
obtained, because the shear rate varies, depending on the location within the viscometer.10–12
Generally, in rotational viscometry, a constant,
that is the shear rate, allows for a constant, uniform ﬂow in all locations in the viscometer. This
can be used to measure the viscosity of non-Newtonian ﬂuids; however, the equipment is complicated and measurement requires 20–30 min.
Furthermore, it has inferior precision compared
with capillary methods, and it is not suitable for
low-viscosity ﬂuids.16, 17 A large amount of saliva
is needed, and intake saliva needs to be ﬁltered,
eliminating large polymers and making it difficult
to reﬂect the exact properties of saliva. Procedures such as equipment cleaning are complex and
time-consuming, and the equipment is costly. In
addition, with a conventional viscometer, a low
torque is generated, making it difficult to measure a low-viscosity sample.
A cone-plate viscometer can analyze small
samples (2–3 mL). However, it is not suitable for

Journal of
Oral Science & Rehabilitation

Volume 2 | Issue 3/2016 65

Fig. 2
Viscometer reproducibility
using a viscosity standard
ﬂuid.
Fig. 3
The measurements using
different disposable test tubes
and spheres with the viscosity
standard ﬂuid.
Fig. 4
The measurements using
different amounts of viscosity
standard ﬂuid.
Fig. 5
Viscometer reproducibility
using Saliveht.

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in vitro study on viscosity

Figs. 6 & 7

Fig. 6
The measurements using
different disposable test
tubes, spheres and Saliveht.
Fig. 7
The measurements using
different amounts of Saliveht.

measuring samples with low viscosity, such as
saliva. When analyzing low viscosity samples,
such as water, the torque generated is too small,
making stable detection difficult.
Salivary viscosity is not uniform between the
measurement methods and devices. In addition,
even with the same measurement device, the
viscosity is strongly inﬂuenced by the measurement conditions, such as temperature and shear
rate. Researchers have shown ingenuity and creativity in measuring viscosity. The device that we
used is contactless, sealed and rapid, requires
samples of low volume and uses disposable components; these features are absent in a conventional viscometer. The equipment is not contaminated by the sample, and all of the containers
are disposable. The disposability of the cell unit,
which is difficult with conventional methods, is
a major advantage of this method. Therefore, it
is no longer necessary to expend effort in cleaning
after measurement, which is normally a tedious
task. This method is superior for measuring
salivary viscosity because torque is applied to the
rotor without any contact, which has the potential to spread infection and is a major concern
with conventional methods. The EMS viscometer
enables continuous measurement over a wide
range, from 1 to 50,000 mPa s, enabling stable
measurement, even in low-viscosity samples
such as water. Another feature of this device is
the ability to measure both Newtonian ﬂuids and
non-Newtonian ﬂuids. Since viscosity is dependent on temperature, a temperature-sensing
system was built into the device used, enabling
automatic measurement of the temperature dependence of viscosity.18–20 Once the test tube has
been inserted into the device, the sample is measured in 10 s, and therefore the method has been
66 Volume 2 | Issue 3/2016

simpliﬁed. Although the reproducibility of EMS
viscometers has been described, the reproducibility has not been studied in terms of whether
they are suitable for bio-instrumentation. Therefore, ﬁrst, we used a viscosity standard ﬂuid,
which was a Newtonian ﬂuid, to study the reproducibility of the equipment. Low-concentration
solutions are reportedly difficult to measure using
a viscometer. Saliva is a low-viscosity polymer
solution and a non-Newtonian ﬂuid, making viscosity measurement difficult.
A standard viscosity ﬂuid is intended to calibrate the viscometer and exhibit constant viscosity. Because the aim of this study was to measure saliva, the machine settings were adjusted
so that the temperature of the thermostatic bath
would be 36 °C, which is close to body temperature. The rotational speed was set to 1,000 rpm
because the measurements involved low viscosity. When the standard viscosity solution was
used, the viscometer showed high accuracy and
very high repeat accuracy. Very high reproducibility too was observed when investigating
whether reproducibility is affected by different
disposable tubes and spheres. In addition, results
from the investigation in which the test material
was changed showed very high reproducibility.
Furthermore, the study of saliva at low viscosities is important.15 Saliva is affected by both
time and temperature, and the effect is not consistent. Therefore, commercially available artiﬁcial saliva, which has stable properties and known
components and additives, was used. The artiﬁcial saliva is packaged in an aerosol spray and is
easy to use. Its efficacy and stability have been
established and it is clinically useful. The main
component is the same inorganic electrolyte solution as saliva, to which a thickening agent is

Journal of
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in vitro study on viscosity

added. Its pH, speciﬁc gravity and other properties are also similar to those of saliva, and the
salivary viscosity was adjusted to 4~6 mm2/s at
25 °C.
Investigation of the low-viscosity solution
also showed that the viscometer had high accuracy and very high repeat accuracy. Very high
reproducibility too was evident when investigating whether disposable tubes and spheres affect
reproducibility. In addition, the investigation in
which the test material was changed also showed
very high reproducibility. These ﬁndings suggest
that a measurement method using an EMS viscometer, has the potential to easily assess changes
in the properties of saliva, primarily viscosity, in
small samples.

Conclusion
This study aimed to assess the measurement of
viscosity using the newly developed EMS viscometer, which demonstrated high reproducibility,
thereby indicating that simple methods for assessing saliva can be developed.

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

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Amerongen AV. Rheological properties of
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Yasuda M, Kurauchi N, Hara M, Nakamura M,
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Fukunaga K, Onuki M, Ohtsuka Y, Hirano T,
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Journal of
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Volume 2 | Issue 3/2016 67

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) [page_count] => 72 [pdf_ping_data] => Array ( [page_count] => 72 [format] => PDF [width] => 595 [height] => 842 [colorspace] => COLORSPACE_UNDEFINED ) [linked_companies] => Array ( [ids] => Array ( ) ) [cover_url] => [cover_three] =>

[cover] =>

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Table of contents

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