Class II subdivision correction with clear aligners using intermaxilary elastics

Abstract

Background:
To describe an esthetic orthodontic treatment using aligners in an adult patient with class II subdivision associated with crowding and dental crossbite. An 18-year-old hyperdivergent male patient with skeletal class II from mandibular retrusion presented for an orthodontic treatment. Occlusally, the patient presents class II subdivision, crossbite at tooth 4.4, an upper midline deviated towards the left with respect to the lower and facial midlines, and slight crowding in both arches. The patient refused conventional fixed multibracket treatment in favor of aligners. Pre- and post-treatment records as well as 1-year follow-up records are presented.

Findings:
Treatment objectives were achieved in 12 months, and the patient was satisfied with the functional and esthetic outcomes, which were stable at 1 year.

Conclusion:
Combining aligners with appropriate auxiliaries is an efficacious means of resolving orthodontic issues such as class II, dental crossbite, and crowding in a time-frame comparable to that of conventional fixed orthodontics. Furthermore, this system is associated with optimal oral hygiene and excellent esthetics.

Full text

S H O R T R E P O R T Open Access
Class II subdivision correction with clear
aligners using intermaxilary elastics
Luca Lombardo, Anna Colonna
*
, Antonella Carlucci, Teresa Oliverio and Giuseppe Siciliani
Abstract
Background: To describe an esthetic orthodontic treatment using aligners in an adult patient with class II
subdivision associated with crowding and dental crossbite. An 18-year-old hyperdivergent male patient with
skeletal class II from mandibular retrusion presented for an orthodontic treatment. Occlusally, the patient presents
class II subdivision, crossbite at tooth 4.4, an upper midline deviated towards the left with respect to the lower and
facial midlines, and slight crowding in both arches. The patient refused conventional fixed multibracket treatment
in favor of aligners. Pre- and post-treatment records as well as 1-year follow-up records are presented.
Findings: Treatment objectives were achieved in 12 months, and the patient was satisfied with the functional and
esthetic outcomes, which were stable at 1 year.
Conclusion: Combining aligners with appropriate auxiliaries is an efficacious means of resolving orthodontic issues
such as class II, dental crossbite, and crowding in a time-frame comparable to that of conventional fixed
orthodontics. Furthermore, this system is associated with optimal oral hygiene and excellent esthetics.
Background
Nowadays, there is a growing demand for esthetic
treatment among both adolescents [1]andadults
[2]. Indeed, a recent study estimated that 45% of
adults are unhappy with their smile and that 20%
of these have considered undergoing orthodontic
treatment to improve their appearance [3].
Hence, aligner systems must now be able to treat
various types of malocclusion, and over recent
years, many studies have shown their great efficacy
in correcting crowding, misalignment and diastems,
and even complex cases featuring extraction,
open-bite, and poor occlusal relationships [4–8].
Case report
This case report describes an adult male patient with
class II subdivision malocclusion, dental crossbite, and
crowding treated successfully with aligners.
Diagnosis and etiology
An 18-year-old hyperdivergent male patient presented
for treatment. Extraoral photos (Fig. 1) and frontal
examination revealed good incisor exposure; however,
buccal corridors and upper midline deviation towards
the left with respect to the facial midline were present.
The profile had a convex aspect characterized by man-
dibular retrusion and increased lower facial height.
Clinical examination revealed class II subdivision with
lower midline deviation towards the right of the upper
midline, dental crossbite, slight crowding in both arches,
and small alteration of the upper right lateral incisor
morphology.
Periodontal biotype and oral hygiene were good
(Fig. 2).
Panoramic radiography revealed full dentition, a lack
of bone defects, no infection and no temporomandibular
joint abnormalities (Fig. 3).
Latero-lateral teleradiograpy (Fig. 4) showed skeletal
class II from mandibular retrusion, and a hyperdivergent
facial type; maxillary incisor were proclined and man-
dibular incisors had a correct inclination. Overbite and
overjet were increased as reported in Table 1.
Clinical examination showed no sign of bad habits.
Treatment objectives
The primary objective was to achieve a molar and ca-
nine class I and centering the upper midline with the
* Correspondence: annachiara.colonna@gmail.com
Postgraduate School of Orthodontics, University of Ferrara, Ferrara, Italy
© The Author(s). 2018 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0
International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and
reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to
the Creative Commons license, and indicate if changes were made.
Lombardo et al. Progress in Orthodontics (2018) 19:32
https://doi.org/10.1186/s40510-018-0221-5

lower and facial midlines. Additional objectives were
to correct the crowding and dental crossbite, obtain
ideal overjet and overbite (Fig. 5), improve facial es-
thetics, and reduce black buccal corridors during
smile.
Treatment alternatives
As there were no major skeletal discrepancies, a com-
bined orthodontic/surgical approach was ruled out.
Fixed multibracket treatment with extraction of four
premolars was considered, but also excluded due to
potential worsening of the profile. The patient was
therefore offered a treatment plan involving unilateral
distalization by fixed multibracket appliances in order
to center the upper midline with the lower and facial
midlines.However,thepatient refused this option due
to the unsightliness of the device, and we therefore
agreed upon a non-extractive treatment with F22
aligners (Sweden & Martina, Due Carrare, Italy) for
unilateral distalization and mesialisation of the lower
arch in order to correct the class II relationship.
Treatment progress
The virtual set-up dictated 20 treatment steps for each
arch. To achieve upper midline correction, the plan in-
volved distorotation of teeth 1.6 (22°) and 1.7 (13°) in as-
sociation with distalization. The use of class II elastics
had a double function: the anchorage, used to obtain
simultaneous distalization of the elements of the quad-
rant I and support the correction of the lower midline.
In the lower arch, the plan involved mesorota-
tion of teeth 4.6 and 4.7 associated with mesial
tipping. The plan also involved alignment of the
arches and retroclination of the upper incisors.
In order to achieve correct alignment and valid
intercuspidation, vestibular grip points on teeth 1.6,
1.7, 4.5, 4.4, and 4.3 were planned, alongside 0.2 mm
of stripping at each interproximal point in the lower
right sector, from the mesial surface of tooth 4.6 to
the distal surface of 4.2.
In order to promote achievement of class I,
6 oz. intermaxillary elastics were to be hooked
directlyontheappositenotchesinthealignersat
the upper canines and lower first molars from
Fig. 1 Pre-treatment extraoral photos
Fig. 2 Pre-treatment intraoral photos
Lombardo et al. Progress in Orthodontics (2018) 19:32 Page 2 of 8

step 1 onwards (Fig. 6). The patient was
instructed to wear each aligner for 22 h per day
and to move on to the next one in the series after
14 days.
After 10 months of treatment, the treatment objectives
had been successfully fulfilled, although it was necessary
to plan another three steps per arch for detailed finish-
ing of the case and complete class correction. Specific-
ally, the derotation of teeth 4.5, 1.6, and 1.5 was
improved.
Treatment results
Post-treatment records demonstrate satisfactory final re-
sults with all objectives achieved. Extraoral photos show
a good profile, correct incisor exposure during smile and
the absence of buccal corridors (Fig. 7). Intraoral exam-
ination reveals the achievement of all planned objectives,
namely class I, centered midlines, and crowding correc-
tion (Fig. 8). Post-treatment panoramic radiography
(Fig. 9) showed good root parallelism, no sign of crestal
bone height reduction, and no evidence of apical root
resorption. Cephalometric indices and post-treatment
latero-lateral teleradiograpy show good vertical control and
proclination of the lower incisors (Table 1). Superimpos-
ition of pre- and post-treatment cephalometric tracings
(Figs. 4,10,11,12,and13), carried out according to the
methodology described in the images captions as developed
by Professor Arne Björk [9,10], highlight the distal tipping
Table 1 Pre- and post-treatment cephalometric values
Pre-treatment value Post-treatment value Ref. value Standard deviation
SNA (°) 79.0 81 82.0 3.5
SNB (°) 72.0 74.8 80.0 3.0
ANB (°) 7.0 6.2 2.0 2.0
Wits appraisal (mm) 4.7 4.0 0.0 1.0
FMA (°) 31.5 30.3 26.0 5.0
MP-SN (°) 40.5 40.3 33.0 6.0
Palatal-mand-angle (°) 27.0 28.0 28.0 6.0
PP-OP (°) 5.3 5.6 10.0 4.0
Mand plane to occ plane (°) 21.5 22.0 18.0 5.0
U1-APo (mm) 9.8 6.8 6.0 2.2
L1-APo (mm) 3.7 3.6 2.0 2.3
U1-palatal plane (°) 118.0 111.0 110.0 5.0
IMPA (°) 92.5 96.5 95.0 7.0
Overjet (mm) 5.5 2.6 3.5 2.5
Overbite (mm) 4.5 2.5 2.5 2.0
Fig. 4 Initial radiographs and cephalometric tracing
Fig. 3 Pre-treatment panoramic radiograph
Lombardo et al. Progress in Orthodontics (2018) 19:32 Page 3 of 8

Fig. 6 Combine use of aligners and class II intermaxillary elastics
Fig. 5 Set-up viewer: the initial occlusion is shown in white and the post-treatment objectives in green
Fig. 7 Post-treatment extraoral photos
Lombardo et al. Progress in Orthodontics (2018) 19:32 Page 4 of 8

movement of the right upper sector, the retroclination
achieved at the upper incisors, and the proclination of the
upper incisors with respect to the basal bone—an accept-
able outcome due to the morphology and conformation of
the patient’s symphysis.
Check-up at 1 year demonstrates the excellent stability
of results (Figs. 14 and 15).
The last pair of aligners was used for retention due to
the elastic propriety of the thermoplastic material [11].
Restoration of the 1.2 was performed in order to im-
prove its morphology.
Discussion
Aligners associated with intermaxillary elastics en-
abled resolution of the malocclusion within a treat-
ment time comparable with that required for
conventional fixed orthodontics, providing the
patient with a comfortable, practical, and esthetic
appliance. This case report is very similar to those
presented in 2010 by Schupp et al. [12]. In our case,
in order to prevent unwanted extrusion and/or rota-
tion and further enhance the esthetics, we used
notches in the aligners at the upper canines and
lower first molars rather than buttons bonded dir-
ectly onto the teeth for attaching the intermaxillary
elastics. Unfortunately, a direct comparison of the
cephalometric indices, especially pertaining to the
lower incisor proclination, was not possible, as these
were not provided in the report.
From a biomechanical perspective, the dental movements
occurred as planned, thanks to the fact that they were
planned within the correct range of predictability [13]and
the excellent properties of the material that the F22 aligners
are made of [11].
In accordance with findings from Janson et al. [14],
and due to the age of the patient, the movements
brought about by the use of intermaxillary elastics were
predominantly dentoalveolar in nature and led to a slight
reduction in the SNA angle, a slight increase in the
Fig. 8 Post-treatment intraoral photos
Fig. 9 Post-treatment panoramic radiograph Fig. 10 Final radiographs and cephalometric tracing
Lombardo et al. Progress in Orthodontics (2018) 19:32 Page 5 of 8

IMPA, and retroclination of the upper incisal sector.
Their main effect was to provide anchorage for the
upper arch, thereby promoting distal tipping and retro-
clination of the upper incisors.
The treatment plan selected proved to be a winning
solution not only in terms of biomechanics, but also as
regards esthetics and periodontal health. Indeed, previ-
ous studies [15] have shown that fixed multibracket ap-
pliances, whether labial or lingual, are associated with an
increase in plaque retention, which in turn may cause an
increase in S. mutans concentration and gingival inflam-
mation. Furthermore, the use of such devices can in-
crease the chromium and nickel concentration in a
patient’s mucosa, potentially resulting in damage to
DNA [16], whereas aligners have not been linked to any
type of cytotoxicity [17].
Moreover, Abbate et al. [18] revealed the microbio-
logical and periodontal changes that may occur during
orthodontic treatment; comparing aligners and fixed ap-
pliances, they found that aligners were associated with
greater compliance, better oral hygiene, less accumulation
of plaque, and less gingival inflammation than fixed appli-
ances. These findings are in line with those reported in a
previous study by Mietheke et al. [19], and in another that
showed an increase in periodontopathic bacteria associ-
ated with a worsening of periodontal health in fixed multi-
bracket orthodontics with respect to aligners [20].
Summary and conclusions
Combined use of aligners and auxiliaries is an efficacious
means of resolving orthodontic issues such as class II,
dental cross-bite, and crowding within a time-frame
Fig. 12 Superimposition of the maxilla. The only stable structure in
the maxilla is the anterior contour of the zygomatic process [9]
Fig. 13 Superimposition of the mandible. The stable anatomical
structures of the mandible are: •The anterior contour of the chin.
•The inner cortical structure at the inferior border of the symphysis.
•Trabecular structures related to the mandibular canal [10]
Fig. 11 Superimposition on the anterior cranial base. Made by “The
structural Method”developed by Professor Arne Björk. The stable
anatomical structures of anterior cranial base are: •The inner
contour of the anterior wall of Sella Turcica. •The mean intersection
point of the lower contours of the anterior clinoid processes and the
contour of the anterior wall of saddle, Walkers’s point. •The anterior
contours of the middle cranial fossae. The contours of the bilateral
fronto-ethmoidal crests. •The cerebral surfaces of the orbital roofs
Lombardo et al. Progress in Orthodontics (2018) 19:32 Page 6 of 8

comparable to conventional fixed orthodontics, but with
excellent esthetics and oral hygiene.
Funding
The authors declare that they have not received funding.
Availability of data and materials
The authors declare that the materials are available.
Authors’contributions
LL is responsible for the treatment planning decision and clinical patient
treatment. CA did the article test production. CA had a hand in the
digital elaboration set-up and planning. OT led the clinical treatment
of the patient. SG contributed in the treatment planning decision and
clinical patient treatment. All authors read and approved the final
manuscript.
Ethics approval and consent to participate
The study was performed in accordance with the Declaration of Helsinki. It is
a case report, and the treatment plan was approved by the Chairman of
Postgraduate School of Orthodontics, University of Ferrara.
Consent for publication
Written informed consent was obtained from the patient for publication of
this short report and any accompanying images.
Competing interests
The authors declare that they have no competing interests.
Publisher’sNote
Springer Nature remains neutral with regard to jurisdictional claims in
published maps and institutional affiliations.
Received: 26 February 2018 Accepted: 14 June 2018
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