Ortho Tribune Middle East & Africa No. 2, 2024

Ortho Tribune Middle East & Africa No. 2, 2024

A Class II open bite case with missing mandibular right central incisor, managed with a hybrid aligner treatment approach

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A Class II open bite case with missing mandibular right central incisor, managed with a hybrid aligner treatment approach
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www.dental-tribune.me

Vol. 14, No. 2

A Class II open bite case with missing
mandibular right central incisor, managed
with a hybrid aligner treatment approach
By Drs Achille Farina & Wajeeh
Khan, Italy & Germany
Introduction
Clear aligners are not always a
perfect alternative to conventional
orthodontic
appliances.1–4
Although theoretically it is possible
to achieve good clinical results
solely with aligners, even in complex cases, such treatments have
substantial limitations and require
much longer to complete. Long
treatment duration and the number of treatment steps required can
make such treatment impractical
and economically unviable. Moreover, since aligner treatment, compared with conventional orthodontic treatment, is more reliant on patient compliance for successful results, in our experience, it is more
challenging to keep patients motivated during treatments of longer
duration.5
Modern orthodontic aligner
therapy has now been used for
over 20 years by orthodontists and
general dentists worldwide. Currently, clear aligners can be successfully used to treat many types
of malocclusion, provided their use
is based on proper diagnostics,
prognosis and treatment planning
and qualiﬁed clinicians are monitoring treatment. Although there
have been signiﬁcant improvements in the eﬃcacy of treatment

with aligners, clear aligners have
their limitations, like any other
treatment appliance. Scientiﬁc evidence shows that the eﬀectiveness
of aligners is less than that of ﬁxed
appliances, especially in achieving
complicated tooth movement.6–10
These limitations can be overcome by not restricting the treatment options to clear aligner use
only and incorporating the use of
other orthodontic auxiliaries and
tools in conjunction with aligners
where needed. This hybrid approach of incorporating orthodontic auxiliaries in treatment planning
where most of the tooth movements are planned with aligners
and auxiliaries are used only for the
more diﬃcult ones is the method
that was used to treat the patient
reported on in this article.
Diagnosis and aetiology
A healthy 39-year-old man presented to our orthodontic oﬃce
with the chief complaint of an unattractive dental appearance and fear
of the orthognathic surgery proposed by another orthodontist.
Clinically, the patient’s proﬁle was
straight, and the frontal view did
not show any facial asymmetry. The
functional examination did not reveal any mandibular deviation or
reduced movements. The patient
had no joint pain, and no joint
noise was observed.

Fig. 9: Pretreatment lateral cephalometric radiograph.

Figs. 1–8: Pretreatment facial and intra-oral photographs.

A bilateral slight Class II molar
occlusion was present, as well as an
open bite and severe crowding in
both arches. The crowding was particularly severe in the mandibular
arch, although the mandibular
right central incisor was missing.
The maxillary incisors were small in
size, suggesting a Bolton discrepancy had all four mandibular incisors been present. A cross bite in
the maxillary left lateral incisor region and a severe distal rotation of
the mandibular left second premolar were also present (Figs. 1–8).

Fig. 10: Pretreatment panoramic radiograph.

From the periodontal point of
view, the patient showed a good
attitude to oral hygiene, but crowding of the mandibular incisors
made cleaning diﬃcult in that area,
causing plaque accumulation and
localised gingival inﬂammation.
The panoramic radiograph revealed the presence of the mandibular third molars and conﬁrmed the
absence of the mandibular right
central incisor (Fig. 10).
The cephalometric analysis
showed a skeletal Class II malocclusion (convexity of Point A: 4.9 mm),

a slightly retruded chin position
(facial depth: 78.1°) and a skeletal
open bite tendency (lower facial
height: 53.19°; facial axis: 80.58°;
Fig. 9). The mandibular incisors
were lingually tipped (Li–APog:
9.3°) and retruded (Li–APog:
1.55 mm), and there was an increased inter-incisal angle of
142.9°.
Treatment objectives
The patient was diagnosed with
a hyper-divergent Class II malocclusion and with bimaxillary retrusion and severe crowding. The
missing mandibular right central
incisor added further complexity to
the treatment. The treatment objectives were to:
1. correct the Class II occlusion;
2. correct the arch length
discrepancy with normalisation of the overjet and
overbite; and
3. improve the smile aesthetics by solving the crowding.
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CASE REPORT

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Treatment alternatives
Several treatment modalities
were considered to achieve an acceptable occlusion and an im-

provement of the dental and facial
aesthetics. Since the patient presented with retruded mandibular
incisors and a missing mandibular

incisor, extraction of the four ﬁrst
premolars was excluded. The absence of a mandibular incisor was
compensated for by the reduced

Figs. 11–15: Initial digital dental models.

Figs. 16–20: Digital set-up of the intended treatment result.

Figs. 21 & 22: Simulation showing the planning for the indirect partial lingual auxiliary—hybrid aligner treatment.

Fig. 23: Treatment evaluation report for the maxillary
arch. Deviation analysis was done by superimposing the
simulated treatment stage data in the CAD software on
to the actual data obtained by scanning the patient’s
teeth at the end of the third phase of the treatment.

Fig. 24: Treatment evaluation report for the mandibular
arch. Deviation analysis was done by superimposing the
simulated treatment stage data in the CAD software on
to the actual data obtained by scanning the patient’s
teeth at the end of the third phase of the treatment.

size of the maxillary lateral incisors
(Bolton discrepancy), and this was
an indication of a nice relationship
between the maxillary and mandibular anterior teeth at the end of
the alignment.
Since the patient had an anterior open bite, planning the treatment using conventional ﬁxed appliances and avoiding extractions
would have been diﬃcult.11–13 This
approach could have furthermore
resulted in the extrusion of the
posterior teeth, thereby increasing
the posterior vertical dimension,
which would have worsened the
anterior open bite by rotating the
mandible posteriorly. The patient
refused the use of high-pull headgear or mini-screws.14–16 That is why
we felt that it would be more appropriate to use aligners to avoid
posterior extrusion and better control the posterior vertical dimension.17 We also felt that it would be
advantageous to use aligners made
of thicker materials to have reasonable vertical control.
With the orthocaps system, it is
possible to employ aligners that
are thicker than those of most
other systems. However, relatively
thick aligners can only be used at
night. Therefore, to have a thin and
clear aligner during the day
(dayCAPS) which would be aesthetically acceptable to the patient, we
choose to use the TwinAligner system (Ortho Caps). This system allowed us to use thicker aligners
(2 mm) at night to achieve our objective while using thin 0.8 mm
aligners during the daytime.
A digital 3D set-up was performed to pre-visualise the intended treatment outcome using
the iSetup software (Ortho Caps).
The ﬁnal set-up was uploaded to
the online clinicians’ portal for approval (Figs. 11–20).
We saw in this simulation that
substantially diﬃcult tooth movements were required, such as bite
closure and rotation of the mandibular left second premolar.18,19
We, therefore, asked Ortho Caps to
use double-layer materials with superior elasticity for the ﬁrst few
phases of the treatment. With this
system, the orthodontist can
choose between diﬀerent materials
and diﬀerent thicknesses based on
the diﬀerent needs in the diﬀerent
phases of the treatment.
We also informed the patient of
the limitations of the aligners in uprighting the mandibular right lateral incisor. 20 Therefore, we advised
the patient that it would be necessary to use a ﬁxed sectional lingual
auxiliary at a certain point during
the treatment. This unique service
of hybrid aligner treatment (HAT) is
also provided by Ortho Caps
(Figs. 21 & 22).

prepared by superimposing the actual tooth positions on to the simulated planned outcomes in the
CAD software (Figs. 23 & 24). This
evaluation is performed using an
optical metrology technique. The
treatment evaluation report was
sent to us with the subsequent
aligners.
Owing to the diﬃculty of the
treatment, we asked to have the
treatment evaluation after every
eighth treatment stage. This helped
us to keep the treatment tracking
under control. The patient changed
the aligners every three weeks, so
each treatment phase lasted for six
months. From the ﬁrst stage, the
patient started using 3⁄16 in., 3.5 oz
Class II elastics, only with the nighttime aligners (nightCAPS).
After 12 months of aligner use
(Figs. 25–29), we ﬁnally had space
for the ﬁxed sectional lingual appliance that we had planned. As described, we asked for an orthocaps
HAT, a new concept based on the
idea of using ﬁxed auxiliary modules (brackets, bands, wires and expansion or anchorage appliances)
simultaneously with aligners to
achieve a more eﬀective treatment
for better clinical results. The exact
times, modalities and use of such
auxiliaries can be determined in the
treatment plan. The method makes
it possible to carry out the bulk of
the movement with aligners while
using auxiliaries as needed primarily to support and enable complex
movement. For the treatment
phase in which a partial lingual appliance was used in this patient, an
indirect bonding tray to bond the
lingual auxiliary was fabricated by
Ortho Caps and sent to us for
bonding the brackets.

Treatment progress
No interproximal reduction was
performed in any phase of the
treatment. With the TwinAligner
system, the treatment is carried out
in phases, and the clinician can
choose the duration of each phase
of treatment (normally eight, ten or
twelve treatment stages). After
every phase, new polyvinylsiloxane
impressions or intra-oral scans
were taken and sent to Ortho Caps.
Ortho Caps then sent back a treatment evaluation report, which is

Method of fabricating the
adapted aligners on the HAT
auxiliary
The HAT technique requires the
aligners to be adapted to the auxiliaries to create the necessary anchorage and allow tooth movement. The subsequent aligners
were made to adapt to the lingual
auxiliary to create the necessary
anchorage so that only those teeth

CAD/CAM method for fabricating the HAT lingual auxiliary
The ﬁnal positions of the mandibular anterior teeth were simulated in the CAD treatment planning software. After moving of the
teeth to their ﬁnal positions, virtual
brackets were placed at appropriate positions on the ﬁnal set-up in
the CAD software. These positions
allow a virtual straight, rectangular
lingual wire to pass passively
through the bracket slots without
colliding with the brackets. In the
next step, the teeth with their respective brackets were moved back
to their original positions. 3D printing was used to print the ﬁnal
moulds with brackets, on which a
silicone transfer tray could then be
formed. Lingual brackets (JOY lingual brackets, Adenta) were then
placed into the silicone transfer
tray to be sent to us for indirect
bonding together with a 0.014 in.
nickel–titanium lingual archwire
(Figs. 30 & 31).

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could be moved that required
movement. This was done by creating 3D models used for thermoforming the aligners that resulted in
the aligners having movement
channels (spaces) incorporated into
their design to allow teeth to move
even when the aligners were placed
over them. Teeth that were used as
anchorage (the mandibular molars,
premolars and canines) had no
spaces so that the aligners ﬁtted
snuggly over them (Figs. 32 & 33).
Rapid alignment was obtained in
the mandibular anterior region in
only nine weeks (Figs. 34–36). A
prebent sectional 0.0175 × 0.0175 in.
Gummetal wire was sent to us for
the ﬁnal stages of the alignment
(Figs. 37–50).
After 26 months, the HAT auxiliary was removed, and few reﬁnement aligners for the ﬁnal mandibular alignment were delivered to
the patient. After a total treatment
time of 28 months, composite restorations were performed on the
maxillary incisors, and the patient
received two rigid retention aligners for night-time wear.
Treatment results
The post-treatment extra-oral
photographs showed the improvement of the smile aesthetics
(Figs. 51–58). A solid bilateral Class I
occlusion was achieved with normal
overjet and overbite. The dental
arches were well aligned and levelled, and even the severe rotation
of the mandibular left second premolar was corrected with aligners
only. The post-treatment cephalometric evaluation (Fig. 59) showed
an improvement in the anteroposterior position of the mandibular incisors (Li–APog: 2.21 mm) while
maintaining the facial height (lower
facial height: 53.12°; facial axis:
83.96°; Table 1).
The panoramic radiograph
showed that the root of the mandibular right lateral incisor had
been uprighted by the HAT auxiliary, without any major root resorptions, while achieving good parallelism with the adjacent teeth
(Fig. 60). The impacted mandibular
third molars were still present because the patient refused to have
them extracted.
Deviation analysis using optical metrology
A deviation analysis between
the ﬁnal clinical result and the initial
situation was conducted to ascertain the extent of vertical movement in the posterior segments
(Fig. 61). This was done to conﬁrm
the hypothesis that the relatively
thick aligners would assist in bite
closure by helping to intrude the
posterior segments. The software
used for this analysis was GOM
Inspect Pro (Carl Zeiss GOM Metrology), which uses a highly accurate method of using optical metrology to measure deviations between two 3D data sets. The results
conﬁrmed intrusive movement of
the molars and premolars, especially on the right side. The aggregate vertical intrusive movement
was in the range of 0.5–1.0 mm.
Conventional cephalometric tracings are unable to recognise movements of this order (Fig. 59).

Discussion
We choose to use thick aligners
because we believed that the interposition of a thick material between the opposing arches would
be beneﬁcial in avoiding posterior
extrusion and, therefore, would be
eﬀective in controlling the vertical
dimension. In addition, we know
from the literature that aligners are
not as eﬃcient as ﬁxed appliances
in correcting tooth inclinations and
obtaining root torque. 20, 21 Based
on current knowledge, we feel that
the hybrid approach is the only way
to achieve considerable root movement in treatment where the bulk
of the movement is planned with
aligners.
Excellent uprighting and root
torque of the mandibular right lateral incisor was achieved with a lingual sectional wire beneath the
mandibular aligner. Moreover, a
solid bilateral Class I occlusion was
established using Class II elastics
worn at night only while the patient
wore the nightCAPS to have vertical control and avoid the extrusion
of the posterior teeth. Since the patient had presented with an open
bite at the beginning of the treatment, the control of the posterior
vertical dimension was mandatory
while extruding the incisors.
Considering the data from the
orthodontic literature, which shows
that premolar rotation is challenging
to correct with aligners,22, 23 we were
astonished that the severe distal rotation of the mandibular left second
premolar was corrected without any
ﬁxed appliances or aux iliaries. We
think that this may have been due to
the type of attachment used and the
elasticity of the double-layer materials used to fabricate the aligners.
This premolar rotation also underlines the importance of case selection and selecting the best options
for tooth movement. Had this case
not posed extremely diﬃcult mandibular anterior crowding requiring
a relatively longer treatment duration, the simultaneous correction
of the mandibular second premolar
rotation using aligners would probably have been impractical. Such
tooth movement alone could not
have justiﬁed an extended treatment duration. Diagnosis and
treatment planning, together with
the use of hybrid auxiliaries, are
paramount in dealing with challenging cases.
The ad hoc composite restorations of the maxillary incisors
were intended to be merely a temporary solution. We recommended
substituting them with feldspathic
or lithium disilicate ceramic veneers. However, the patient was not
interested in any further prosthodontic improvement of the result
obtained.
Unfortunately, all third molars
were still present at the end of the
treatment. The patient would not
agree to have these teeth extracted
despite having been informed of
the risk of pathological changes,
such as infection (pericoronitis),
root resorption, non-restorable
carious lesions, and the development of cysts and tumours, as well
as of a greater accumulation of
bacterial plaque with possible consequent periodontal disease of the
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Figs. 25–29: Clinical progress after 12 months of aligner treatment.

Fig. 30: Indirect bonding tray and 0.014 in. nickel–
tanium wire.

Fig. 32: Sectional lingual appliance in place.

ti-

Fig. 31: Lingual bracket placement.

Fig. 33: Aligner with movement channels incorporated
into the design to allow teeth to move even when the
aligner was placed over them. Teeth used as anchorage
had no spaces so that the aligner ﬁtted snuggly over
them.

Figs. 34–36: Clinical progress after nine weeks of hybrid aligner treatment.

Figs. 37–44: Sequential intra-oral
photographs illustrating progressive alignment of the mandibular
arch.

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CASE REPORT

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Figs. 45–50: : Sequential frontal intra-oral photographs illustrating progressive levelling and alignment and uprighting
of the mandibular right lateral incisor.

Figs. 61: : The deviation analysis showed that there was intrusion of the posterior teeth as expected. The teeth in grey were not included in this analysis, as
the amount of movement exceeded the range of 1 mm selected for this superimposition.

second molars. The patient was
also informed that failure to extract
the third molars could be the cause
of halitosis, recurrent abscesses
and dysodontiasis. 24–26 He therefore signed the supplemental informed consent form provided by
the American Association of
Orthodontists for patients who decline a recommended treatment.

Figs. 51–58: Post-treatment facial and intra-oral photographs.

Pretreatment

Post-treatment

Change

Facial axis (Pt–Gn)

80.58°

83.96°

+3.38°

Facial depth angle

78.1°

78.5°

+0.4°

Mandibular plane angle

25.5°

26.6°

+1.1°

Lower facial height

53.19°

53.12°

-0.07°

Mandibular arch

27.3°

30.9°

+3.6°

Convexity of point A

4.9 mm

3.4 mm

-1.5 mm

Mandibular incisor protrusion

1.4 mm

2.5 mm

+1.1 mm

Mandibular incisor inclination

15.5°

21.7°

+6.2°

Maxillary molar position

7.1 mm

6.7 mm

-0.5 mm

Inter-incisal angle

142.9°

128.0°

-14.9°

Lower lip to E plane

-4.6 mm

-3.6 mm

+1.0 mm

Maxillary depth

87.5°

87.1°

-0.4°

Table 1: Cephalometric analysis.

Fig. 59: Post-treatment lateral
radiograph with cephalometric
tracing.

Fig. 60: Post-treatment panoramic radiograph.

Conclusion
The use of thick materials covering the occlusal surfaces of the
posterior teeth is beneﬁcial in patients where control of the posterior vertical dimension is important
and posterior extrusion must be
avoided. Such cases are mostly
high-angle and exhibit anterior
open bites. In such cases, thicker
aligners are more eﬀective in controlling the vertical dimension. Although a thick aligner at night is
very useful clinically, such aligners
are not suited for daytime use,
since these are aesthetically not acceptable to patients and impair
speech. Therefore, in this case, we
preferred to use diﬀerent thickness
materials for daytime and nighttime use.
The present case report illustrates that in complex cases we can
overcome the limitations of aligners in achieving challenging tooth
movement (i.e. root movement)
with the hybrid approach. As described, by using ﬁxed sectional
auxiliaries in combination with
aligners, we could treat this case to
a high clinical standard. The hybrid
approach, in our view, is the most
eﬃcient and eﬀective method for
treating complex cases with aligners. Therefore, aligner manufacturers should oﬀer these types of
treatment options to assist clinicians in treating such cases while
oﬀering patients an invisible orthodontic treatment. Unfortunately,
very few systems provide this service.
Editorial note: This article was first published in aligners international magazine of aligner orthodontics, Vol. 2, Issue
1/2023.

Dr
Achille
Farina obtained
his
DDM from
the University of Milan in Italy in
1988, a university diploma in orthodontics and dental and maxillofacial orthopaedics from the
University of Burgundy in Dijon
in France in 1996 and an MSc in
orthodontics from the University of Cagliari in Italy in 2000. He
is in private orthodontic practice
in Brescia in Italy. Dr Farina is an
international member of the American Association of Orthodontists
and a fellow of the World Federation of Orthodontists.

After graduating from the
University of
the Punjab in
Lahore in Pakistan in dental surgery
(BDS), Dr Wajeeh Khan undertook
postgraduate training in oral surgery at the department of maxillofacial surgery in the University Medical Centre of Münster from 1986
to 1989 in Germany and was awarded a Dr. med.dent. by the university in 1989. He ﬁnished a three-year
postgraduate degree in orthodontics at the same university in 1996
and was admitted as a specialist
in orthodontics that same year.
Dr Khan maintained a private orthodontic practice from 1996 to 2019.
He is the founder of the orthocaps
system and the managing director of
the company. He is an international
member of the American Association
of Orthodontics and a fellow of the
World Federation of Orthodontists.

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A Class II open bite case with missing mandibular right central incisor, managed with a hybrid aligner treatment approach
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A Class II open bite case with missing mandibular right central incisor, managed with a hybrid aligner treatment approach

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