ArticlePDF Available

Class II subdivision correction with clear aligners using intermaxilary elastics


Abstract and Figures

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.
Content may be subject to copyright.
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
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.
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 [48].
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
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:
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 (, 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
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
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
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
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 bonean accept-
able outcome due to the morphology and conformation of
the patients 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.
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
patients 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 Methoddeveloped 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, Walkerss 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.
The authors declare that they have not received funding.
Availability of data and materials
The authors declare that the materials are available.
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
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.
Springer Nature remains neutral with regard to jurisdictional claims in
published maps and institutional affiliations.
Received: 26 February 2018 Accepted: 14 June 2018
1. Walton DK, Fields HW, Johnston WM, Rosenstiel SF, Firestone AR,
Chirstensen JC. Orthodontic appliance preferences of children and
adolescents. Am J Orthod Dentofac Orthop. 2010;138(6):698.e112.
2. Feu D, Catharino F, Duplat CB, Capelli Junior J. Esthetic perception and
economic value of orthodontic appliances by lay Brazilian adults. Dental
Press J Orthod. 2012;17(5):10214.
3. British Orthodontic Society. News release, news/
NOWYouGovSurvey. Accessed 9 Apr 2013.
4. Boyd RL, Miller RJ, Vlaskalic V. The Invisalign system in adult orthodontics:
mild crowding and space clousure cases. J. Clin. Orthod. 2000;34(4):04203.
5. Womack WR. Four-premolar extraction treatment with Invisalign. J Clin
Orthod. 2006;40:493500.
6. Hönn M, Göz G. A premolar extraction case using the Invisalign system. J
Orofac Orthop. 2006;67:38594.
7. Boyd RL. Complex orthodontic treatment using a new protocol for the
Invisalign appliance. J Clin Orthod. 2007;41:52547.
8. Boyd RL. Esthetic orthodontic treatment using the Invisalign appliance for
moderate to complex malocclusions. J. Dent. Ed. 2008;72:94867.
9. Björk A, Skieller V. Growth of the maxilla in three dimensions as revealed
radiographically by the implant method. Br J Orthod. 1977;4:5364.
Fig. 14 Extraoral photos at 1 year
Fig. 15 Intraoral photos at 1 year
Lombardo et al. Progress in Orthodontics (2018) 19:32 Page 7 of 8
10. Björk A. Prediction of mandibular growth rotation. Am J Orthod. 1969;
11. Lombardo L, Martines E, Mazzanti V, Arreghini A, Mollica F, Siciliani G. Stress
relaxation properties of four orthodontic aligner materials: a 24-hour in vitro
study. Angle Orthod. 2017;87(1):118.
12. Schupp W, Haubrich J, Neumann I, Class II. Correction with the Invisalign
system. J Clin Orthod. 2010;44(1):2835.
13. Rossini G, Parrini S, Castroflorio T, Deregibus A, Debernardi CL. Efficacy of
clear aligners in controlling orthodontic tooth movement: a systematic
review. Angle orthod. 2015;85(5):8819.
14. Janson G, Sathler R, Fernandes TM, Branco NC, Freitas MR. Correction of
class II malocclusion with class II elastics: a systematic review. Am J Orthod
Dentofac Orthop. 2013;143(3):38392.
15. Lombardo L, Ortan YÖ, Gorgun Ö, Panza C, Scuzzo G, Siciliani G. Changes in
the oral environment after placement of lingual and labial orthodontic
appliances. Prog Orthod. 2013;11(14):28.
16. Hafez HS, Selim EM, Kamel Eid FH, Tawfik WA, Al-Ashkar EA, Mostafa YA.
Cytotoxicity, genotoxicity and metal release in patients with fixed
orthodontic appliances: a longitudinal in-vivo study. Am J Orthod Dentofac
Orthop. 2011;140(3):298308.
17. Eliades T, Pratsinis H, Athanasiou AE, Eliades G, Kletsas D. Cytotoxicity and
estrogenicity of Invisalign appliances. Am J Orthod Dentofac Orthop. 2009;
18. Abbate GM, Caria MP, Montanari P, Mannu C, Orrù G, Caprioglio A, Levrini L.
Periodontal health in teenagers treated with removable aligners and fixed
orthodontic appliances. J Orofac Orthop. 2015;76(3):24050.
19. Miethke RR, Vogt S. A comparison of the periodontal health of patients
during treatment with the Invisalign system and with fixed orthodontic
appliances. J Orofac Orthop. 2005;66(3):21929.
20. Karkhanechi M, Chow D, Sipkin J, Sherman D, Boylan RJ, Norman RG, Craig
RG, Cisneros GJ. Periodontal status of adult patients treated with fixed
buccal appliances and removable aligners over one year of active
orthodontic therapy. Angle Orthod. 2013;83(1):14651.
Lombardo et al. Progress in Orthodontics (2018) 19:32 Page 8 of 8
... All constructions were assumed to be made of linear, elastic, isotropic, and homogeneous materials. Two group sets with three submodels (Fig. 1) were created to simulate the simplified sequential molar distalization process using design inspiration drawn from prior work [26,27]. Group set I was used to simulate 0.25 mm distal movement of the 2nd molars, whereas group set II was used to model 0.25 mm distal movement of the 1st molar after the 2nd molar had been moved distally by 2 mm. ...
... Subsequently, in group set II, the 2nd molar was displaced distally by 2 mm to reach a target position, followed by the 1st molar underwent a distal movement of 0.25 mm distally to establish a loading condition CA [17]. Finally, in models B and C, a series force of 100, 150, and 200 g was applied by a spring attached to the microimplants and the buttons or precision cuts on each side [26]. NiTi springs are employed for the purpose of simulating the implementation of elastic traction. ...
Full-text available
Introduction This study aims to investigate the biomechanical effects of anchorage reinforcement using clear aligners (CAs) with microimplants during molar distalization. And also explores potential clinical strategies for enhancing anchorage in the sequential distalization process. Methods Finite element models were established to simulate the CAs, microimplants, upper dentition, periodontal ligament (PDL), and alveolar bone. In group set I, the 2nd molars underwent a distal movement of 0.25 mm in group set II, the 1st molars were distalized by 0.25 mm after the 2nd molars had been placed to a target position. Each group set consisted of three models: Model A served as the control model, Model B simulated the use of microimplants attached to the aligner through precision cuts, and Model C simulated the use of microimplants attached by buttons. Models B and C were subjected to a series of traction forces. We analyzed the effective contribution ratios of molar distalization, PDL hydrostatic stress, and von Mises stress of alveolar bone. Results The distalization of the 2nd molars accounted for a mere 52.86% of the 0.25-mm step distance without any reinforcement of anchorage. The remaining percentage was attributed to the mesial movement of anchorage teeth and other undesired movements. Models B and C exhibited an increased effective contribution ratio of molar distalization and a decreased loss of anchorage. However, there was a slight increase in the undesired movement of molar tipping and rotation. In group set II, the 2nd molar displayed a phenomenon of mesial relapse due to the reciprocal force produced by the 1st molar distalization. Moreover, the efficacy of molar distalization in terms of contribution ratio was found to be positively correlated with the magnitude of force applied. In cases where stronger anchorage reinforcement is required, precision cuts is the superior method. Conclusions The utilization of microimplants in conjunction with CAs can facilitate the effective contribution ratio of molar distalization. However, it is important to note that complete elimination of anchorage loss is not achievable. To mitigate undesired movement, careful planning of anchorage preparation and overcorrection is recommended.
... Elastics with attachment auxiliaries in Invisalign ® have been reported to be an effective way of correcting molar relationships in class II malocclusion. A case report of an adult patient with class 2 subdivision malocclusion was documented with a successful outcome of a corrected molar relationship [25]. Another study evaluated the effects of Invisalign ® and class II elastics in adult patients with class II malocclusion. ...
... Orthodontic treatment utilizing CAD-CAM technology has gained global support, and within this realm, Clear Aligners have expanded their scope of applications and amassed evidence for treating increasingly complex cases. [1][2][3] This article aims to showcase the orthodontic treatment of a patient with Class I malocclusion using CAD-CAM-manufactured clear aligners. The patient's primary concern revolved around smile aesthetics. ...
Full-text available
The correction of root torque is a crucial aspect of orthodontic treatments. With the growing popularity of clear aligners, there is a need to establish their effectiveness in controlling root torque. This study presents a case of retreatment in which root positioning correction was required for multiple teeth. The outcomes demonstrated that two sets of aligners, along with additional refinement, were necessary to achieve a favorable clinical outcome in terms of aesthetics and periodontal health. While the results were positive, it is recommended that further studies like this one be conducted to gather more evidence regarding the use of aligners for orthodontic root torque correction. Furthermore, pre-, and post-treatment tomographic examinations could provide more precise insights into the potential of aligners in correcting root torque.
... In these cases, it is therefore suggested to use higher force on the intermaxillary elastics or to use the elastics as an anchorage resource in sequential distalization biomechanics, with or without skeletal anchorage. [29][30][31][32] ...
Full-text available
Introduction Intermaxillary elastics are orthodontic resources widely used in various malocclusions. Their main advantages are low cost, easy insertion and removal by patients, and application versatility. As main disadvantages, we can highlight the need for cooperation from patients and the side effects normally present in treatments with this resource. Knowledge of the biomechanics involved in the use of intermaxillary elastics is essential to take full advantage of the desired effects and avoid unwanted effects in their use. Objective Therefore, the objective of this article is to describe the anchorage preparation, connection methods, time and force of use, and side effects involved in the use of intermaxillary elastics for the treatment of anteroposterior, vertical and transverse problems. For that, clinical cases and biomechanics schemes will be presented, in which all these details will be described. Keywords: Orthodontics; Malocclusion, Angle Class II; Orthodontics, corrective
... 17 Over the last 20 years, thermoplastic removable appliances have evolved, and clear aligner treatment techniques have been refined. With the help of extra tools such as mini-screws, elastics, sectional wires, and rapid palatal expanders, [18][19][20][21][22] clear aligners can now be used for more than just simple cases. 15,16 The goal of this review is to provide a concise and up-todate overview of the impact of clear aligners on oral health and microbiome during orthodontic treatment as well as to provide cleaning and disinfecting methods for clear aligners. ...
Full-text available
The demand for clear aligners has risen over the past decade because they satisfy patients' desire for less noticeable and more comfortable orthodontic appliances. Because clear aligners are increasingly used in orthodontics, there is a big push to learn more about the physiologic and microbial changes that occur during treatment. The present work highlighted further links between clear aligners and changes in oral health and the oral microbiome and provided plaque control methods for clear aligner trays. Existing literature revealed that clear aligners have no significant influence on the structure of the oral microbiome during orthodontic therapy. Clear aligner treatment demonstrated promising results in terms of controlling plaque index, gingival health, and the prevalence of white spot lesions. Nevertheless, grooves, ridges, microcracks, and abrasions on the aligner surface would provide a prime environment for bacterial adherence and the development of plaque biofilms. A combination of mechanical and chemical methods seems to be a successful approach for removing plaque biofilm from aligners whilst also preventing pigment adsorption.
... [8][9][10] Though scholarly literature for treating complex cases is still in its early phase, published case reports have demonstrated satisfying outcomes with complex cases, such as those involving class II malocclusions. [10][11][12] Furthermore, the precision of movements has improved exponentially in recent years reaching values of 70%-80% due to the continuous research performed by Align Technology and the incorporation of attachments and auxiliaries in the treatment protocols. 13 Moreover, the predictability of crowding resolution with aligners was shown recently to be high. ...
Full-text available
To describe an esthetic orthodontic treatment using aligners in an adult patient with dental class II malocclusion associated with crowding. A 25‐year‐old female patient with skeletal class I, bilateral class II relation, increased overjet and overbite and crowding in both arches presented for orthodontic treatment. The patient refused conventional fixed multibracket treatment in favor of aligners. Pre‐ and post‐treatment records are presented. Treatment objectives were achieved in 10 months, and the patient was satisfied with the functional and esthetic outcomes. Combining aligners with appropriate attachment location and geometry is an efficacious means of resolving orthodontic issues such as class II malocclusion in a time frame comparable to that of conventional fixed orthodontics. Staging in distalization increases the predictability of movement. Furthermore, this system is associated with optimal oral hygiene and excellent esthetics.
Full-text available
Objetivo: Os alinhadores transparentes são uma alternativa aos aparelhos ortodônticos convencionais, sendo cada vez mais indicados devido à sua estética discreta e conforto para os pacientes. A busca por uma aparência estética desempenha um papel significativo na procura por tratamentos odontológicos restauradores. Tem-se por objetivo saber os reais benefícios dos alinhadores transparentes em comparação com os aparelhos ortodônticos convencionais no contexto do tratamento restaurador estético. São abordadas questões relacionadas à estabilidade dos resultados, tempo de tratamento, conforto para o paciente e impacto psicológico positivo. Metodologia: o presente estudo se trata de uma revisão narrativa da literatura que utilizou as bases de dados: Pubmed (NIH), SciELO, Medline e Google Acadêmico, e buscou por artigos publicados entre os anos de 2013 a 2023 e após seguir os critérios de inclusão e exclusão, 18 artigos foram considerados elegíveis. Resultados: O tratamento restaurador estético envolve a melhoria da aparência dos dentes, seja através de clareamento dental, restaurações diretas ou indiretas, facetas de porcelana, entre outros procedimentos. Os alinhadores transparentes podem desempenhar um papel importante nesse processo, permitindo uma abordagem menos invasiva e mais conservadora. Porém, por outro lado, existem os aprelhos convencionais, que apesar de serem anti-estetéticos, conseguem desempenhar papeis que o aparelho estetico não consegue. Conclusão: alinhadores transparentes apesar de apresentarem extensas vantagens em especial o conforto e estética, os movimentos gerados para o tratamento de defeitos mais graves ainda é limitado em comparação aos aparelhos ortodônticos convencionais.
Objectives The aim of the study was to evaluate the effect of resin attachments on the displacement and deformation pattern of the aligner plastic, determine the center of rotation and stress distribution in the upper canine during space closure using the finite element method (FEM), and evaluate the plastic Aligner deformation. Materials and Method s A computer-assisted design model of the superior right hemiarch was constructed with the simulation of a first premolar extraction and a canine distalization, recreating the periodontal ligament and alveolar bone. FEMs were created to analyze the behavior of stress and displacement of the upper right canine with aligners in four situations, one without attachment, and three with bonded attachments (vertical rectangular, rectangular beveled, optimized root control). In addition, the plastic deformation of the aligner was evaluated. Results In the simulation without attachment, there was no apical movement, while with vertical rectangular and rectangular beveled the behavior was similar with crown distal displacement and mesial apex displacement. The optimized attachment had a better movement control of the canine body respecting the crown and apical movement toward the same direction. The mayor plastic deformation was shown without attachment and no deformation was evidenced with optimized attachment. Conclusion The FEM showed that nevertheless the optimized attachment produced a distal crown and apical displacement with the use of plastic aligners during the space closure, the apex only moved ¼ of the distal crown movement. Our results suggest that to obtain a pure translation of the canine with aligners, it would be necessary the use of auxiliars which complement the needed biomechanics.
Introduction: Class II elastics, in combination with clear aligners (CA), are efficient for molar distalization. However, the effects of this combination on intermaxillary molar relationship correction have yet to be investigated. This study aimed to investigate the actual contribution ratio of the maxillary and mandibular molars for total molar relationship correction during maxillary molar distalization using Class II elastics with CA and further explore therapeutic recommendations for clinical practice. Methods: Finite element models (FEMs) were established, including the distalization of the second molars (Set I), followed by the distalization of the first molars (Set II). Model A simulated elastics attached by precision cutting, whereas Model B simulated elastics attached to buttons. Force magnitudes of 100 g, 150 g, and 200 g of force were applied. We recorded the contribution ratio of the maxillary and mandibular molars for total molar relationship correction, effective distalizing distance in 0.25 mm step distance, tipping and rotation angles, and the hydrostatic stress in the periodontal ligament. Results: During maxillary molar distalization, mesialization of the mandibular molar had a notable contribution ratio for molar relationship correction. The mandibular first molar was mesialized with mesiolingual rotation tendency. Approximately half of the 0.25 mm step distance was occupied by maxillary molar distalization; the remainder was occupied by anchorage teeth mesialization and tipping or rotation. When traction forces increased, the total molar relationship correction and effective distalization increased; the mandibular molars mesialization contribution ratio also increased, as did rotation and inclination tendency. Precision cutting had a higher total molar relationship correction and more effective distalization than a button but also had a larger contribution ratio of mandibular molar mesialization and inclination or rotation. Conclusions: Mandibular molar mesialization should be considered when correcting the molar relationship using CA with intermaxillary elastics during maxillary molar distalization. It is also important to consider the anchorage teeth mesialization and undesired tipping or rotation.
Full-text available
The purpose of this study was to explore the microbiological and periodontal changes occurring in adolescents during 12 months of orthodontic therapy with removable aligners and with fixed appliances. During the years 2012-2013, 50 teenagers aged 10-18 years with similar initial orthodontic conditions participated in this trial in a university clinic in northern Italy. After receiving professional oral hygiene and instructions on a standardized oral hygiene protocol, the adolescents were randomly assigned to either orthodontic treatment with traditional fixed brackets (n = 25) or to treatment with Invisalign® aligners (n = 25). Subgingival microbiological samples, probing depth (PD), plaque index (PI), and bleeding on probing (BOP) were obtained and documented from the mesiovestibular subgingival sulcus of the upper right first molar and left central incisor at the beginning of treatment and 3, 6, and 12 months later. Compliance with oral hygiene procedures, full mouth plaque score (FMPS), and full mouth bleeding score (FMBS) were assessed at the beginning of treatment and 12 months later. Two sample independent t-tests and the χ(2) test were used to study whether the indices of periodontal health differed in the teenagers due to the experimental conditions. None of the patients was positive for the periodontal anaerobes analyzed. The PI, PD, BOP, FMPS, and FMBS scores were significantly lower and compliance with oral hygiene was significantly higher in the group treated with Invisalign® than in the group treated with fixed brackets. Teenagers treated with removable appliances display better compliance with oral hygiene, less plaque, and fewer gingival inflammatory reactions than their peers with fixed appliances.
Full-text available
Objective: To assess the scientific evidence related to the efficacy of clear aligner treatment (CAT) in controlling orthodontic tooth movement. Materials and methods: PubMed, PMC, NLM, Embase, Cochrane Central Register of Controlled Clinical Trials, Web of Knowledge, Scopus, Google Scholar, and LILACs were searched from January 2000 to June 2014 to identify all peer-reviewed articles potentially relevant to the review. Methodological shortcomings were highlighted and the quality of the studies was ranked using the Cochrane Tool for Risk of Bias Assessment. Results: Eleven relevant articles were selected (two Randomized Clinical Trials (RCT), five prospective non-randomized, four retrospective non-randomized), and the risk of bias was moderate for six studies and unclear for the others. The amount of mean intrusion reported was 0.72 mm. Extrusion was the most difficult movement to control (30% of accuracy), followed by rotation. Upper molar distalization revealed the highest predictability (88%) when a bodily movement of at least 1.5 mm was prescribed. A decrease of the Little's Index (mandibular arch: 5 mm; maxillary arch: 4 mm) was observed in aligning arches. Conclusions: CAT aligns and levels the arches; it is effective in controlling anterior intrusion but not anterior extrusion; it is effective in controlling posterior buccolingual inclination but not anterior buccolingual inclination; it is effective in controlling upper molar bodily movements of about 1.5 mm; and it is not effective in controlling rotation of rounded teeth in particular. However, the results of this review should be interpreted with caution because of the number, quality, and heterogeneity of the studies.
Full-text available
This study compared the oral hygiene and caries risk of patients treated with labial and lingual orthodontic appliances throughout a prospective evaluation of the status of the oral environment before and after bracket placement. A total of 20 orthodontic patients aged 19 to 23 years were included in the study and were divided into two groups: 10 patients wore Roth labial appliance (American Orthodontics, Sheboygan, WI, USA) and 10 patients wore STb lingual appliance (Ormco Corporation, Glendora, CA, USA). Plaque index (PI), gingival bleeding index (GBI), salivary flow rate, saliva buffer capacity, salivary pH, and Streptococcus mutans and Lactobacillus counts in saliva were determined at three time points: before orthodontic appliance placement (T0), 4 weeks after bonding (T1), and 8 weeks after bonding (T2). After appliance placement, all patients were periodically educated to the oral hygiene procedures. Wilcoxon rank and Mann-Whitney U tests were used to determine intragroup and intergroup differences as regards qualitative data. To compare quantitative data between the groups, chi-square and Fisher's exact tests were undertaken, while intragroup differences were tested with McNemar test. The level of statistical significance was set at p < 0.05. Statistical analysis of the data obtained revealed a statistically significant difference between the data of T0 and T1 and the data of T0 and T2 of the PI scores and between T0 and T2 of the GBI scores in the group treated with the lingual appliance. The GBI value increased significantly between T0 and T1 but decreased significantly between T1 and T2 (p < 0.01) in the group treated with labial appliance. S. mutans counts increased significantly between T0 and T2 in the saliva samples of patients treated with lingual appliance. No statistically significant differences were found between S. mutans and Lactobacillus counts at the three terms of saliva collection in patients treated with labial appliance. No statistically significant differences were found between the two groups at the three time points as regards the salivary flow rate and saliva buffer capacity. Lingual and labial orthodontic appliances showed a different potential in modifying the investigated clinical parameters: patients wearing STb lingual orthodontic appliance had more plaque retention 4 and 8 weeks after bonding, while there were more gingival inflammation and more S. mutans counts 8 weeks after bonding. No differences were found between the two groups as regards the Lactobacillus counts, the salivary flow rate, and saliva buffer capacity.
Full-text available
Objective: To evaluate the esthetic perception of different appliances by Brazilian lay adults and its influence in the attributed value of orthodontic treatment, considering evaluators' socioeconomic status, age and gender. Methods: Eight different combinations of orthodontic appliances and clear tray aligners were placed in a consenting adult with pleasing smile. Standardized frontal photographs were captured and incorporated into a research album. A sample of adults (n = 252, median = 26 years old) were asked to rate each image for (1) its attractiveness on a visual analog scale and (2) the willingness to pay (WTP) for a cosmetic appliance when compared to a standard metalic appliance and a clear tray aligner. Comparisons between the appliances' attractiveness were performed using the Friedman's test and Dann's post-hoc test. Correlation between appliances' attributed value, socioeconomic status, age, gender, and esthetic perception was assessed using Spearman's correlation analysis. Results: Attractiveness ratings of orthodontic appliances varied significantly in the following hierarchy: Clear aligners>sapphire brackets>self-ligating/conventional stainless steel brackets>and golden metal appliances. The correlation between WTP and esthetic perception was week. However, for individuals with better socioeconomic status and aged between 17-26 years old significantly, a significantly higher WTP was found. Conclusion: Clear aligners and sapphire brackets with esthetic archwire were considered better esthetic options in this sample. Nevertheless, patients were not willing to pay more money for appliances they deemed more esthetic, however, they were significantly influenced by their socioeconomic level and age.
Full-text available
Objective: To compare the periodontal status of adults treated with fixed buccal orthodontic appliances vs removable orthodontic aligners over 1 year of active therapy. Materials and methods: The study population consisted of 42 subjects; 22 treated with fixed buccal orthodontic appliances and 20 treated with removable aligners. Clinical indices recorded included: plaque index (PI), gingival index (GI), bleeding on probing (BOP), and probing pocket depth (PPD). Plaque samples were assessed for hydrolysis of N-benzoyl-DL-arginine-naphthylamide (BANA test). Indices and BANA scores were recorded before treatment and at 6 weeks, 6 months, and 12 months after initiation of orthodontic therapy. Results: After 6 weeks, only mean PPD was greater in the fixed buccal orthodontic appliance group. However, after 6 months, the fixed buccal orthodontic appliance group had significantly greater mean PI, PPD, and GI scores and was 5.739 times more likely to have a higher BANA score. After 12 months, the fixed buccal orthodontic appliance group continued to have greater mean PI, GI, and PPD, while a trend was noted for higher BANA scores and BOP. Conclusions: These results suggest treatment with fixed buccal orthodontic appliances is associated with decreased periodontal status and increased levels of periodontopathic bacteria when compared to treatment with removable aligners over the 12-month study duration.
Objective: To investigate the stress release properties of four thermoplastic materials used to make orthodontic aligners when subjected to 24 consecutive hours of deflection. Materials and methods: Four types of aligner materials (two single and two double layered) were selected. After initial yield strength testing to characterize the materials, each sample was subjected to a constant load for 24 hours in a moist, temperature-regulated environment, and the stress release over time was measured. The test was performed three times on each type of material. Results: All polymers analyzed released a significant amount of stress during the 24-hour period. Stress release was greater during the first 8 hours, reaching a plateau that generally remained constant. The single-layer materials, F22 Aligner polyurethane (Sweden & Martina, Due Carrare, Padova, Italy) and Duran polyethylene terephthalate glycol-modified (SCHEU, Iserlohn, Germany), exhibited the greatest values for both absolute stress and stress decay speed. The double-layer materials, Erkoloc-Pro (Erkodent, Pfalzgrafenweiler, Germany) and Durasoft (SCHEU), exhibited very constant stress release, but at absolute values up to four times lower than the single-layer samples tested. Conclusions: Orthodontic aligner performance is strongly influenced by the material of their construction. Stress release, which may exceed 50% of the initial stress value in the early hours of wear, may cause significant changes in the behavior of the polymers at 24 hours from the application of orthodontic loads, which may influence programmed tooth movement.
Conference Paper
Although attractiveness and acceptability of orthodontic appliances have been rated by adults for themselves and adolescents, children and adolescents have not provided any substantial data. Objective: To evaluate children and adolescent preferences and acceptability of orthodontic appliances. Methods: Images of orthodontic appliances previously captured and standardized for the research of Zuichkovski et al and Rosvall et al were selected and incorporated into a computer based survey. Additional images of shaped brackets and colored elastomeric ties, as well as discolored clear elastomeric ties were captured and incorporated onto existing survey images with Adobe Photoshop. The survey displayed twelve orthodontic appliance variations to 135 children (n=45 of each 9-11 years, 12-14 years, 15-17 years). Subjects rated each image for attractiveness on a visual analog scale (VAS) and acceptability (yes/no). All images were displayed and rated twice to assess rater reliability. Results: Overall reliability for attractiveness rating was r=0.74 and k=0.66 for acceptability. There were significant differences in bracket attractiveness and acceptability among all subjects combined, between age groups and between gender groups. Among all subjects, the highest rated appliances were clear aligners, twin brackets with colored ties, and shaped brackets with and without colored ties. Colored elastomeric ties improved attractiveness significantly over brackets without colored ties. Ceramic brackets with discolored ties were rated lower than ceramic brackets with new ties, and scored lowest in acceptability and attractiveness in all age groups. Female subjects rated shaped brackets significantly higher than male subjects. Conclusions: The results of this research demonstrate that children's preference for orthodontic appliances differs by age and gender. Adult and child preferences differ. Supported by Delta Dental.
Although Class II elastics have been widely used in the correction of Class II malocclusions, there is still a belief that their side effects override the intended objectives. The aim of this systematic review was to evaluate the true effects of Class II elastics in Class II malocclusion treatment. A search was performed on PubMed, Scopus, Web of Science, Embase, Medline, and Cochrane databases, complemented by a hand search. Study eligibility criteria were the application of Class II elastics in Class II malocclusion treatment and the presentation of dental or skeletal outcomes of treatment. All age groups were included. The search indentified 417 articles, of which 11 fulfilled the inclusion criteria. Four studied the isolated effects of Class II elastics, and 7 were comparisons between a single use of elastics and another method for Class II malocclusion correction. Because of the differences in treatment modalities in these articles, a meta-analysis was not possible. Based on the current literature, we can state that Class II elastics are effective in correcting Class II malocclusions, and their effects are primarily dentoalveolar. Therefore, they are similar to the effects of fixed functional appliances in the long term, placing these 2 methods close to each other when evaluating treatment effectiveness. Little attention has been given to the effects of Class II elastics on the soft tissues in Class II malocclusion treatment.
Treatment with fixed orthodontic appliances in the corrosive environment of the oral cavity warrants in-vivo investigations of biocompatibility. Eighteen control and 28 treated subjects were evaluated longitudinally. Four combinations of brackets and archwires were tested. Buccal mucosa cell samples were collected before treatment, and 3 and 6 months after appliance placement. The cells were processed for cytotoxicity, genotoxicity, and nickel and chromium contents. In the treatment group, buccal mucosa cell viability values were 8.1% at pretreatment, and 6.4% and 4.5% at 3 and 6 months, respectively. The composite score, a calculated DNA damage value, decreased from 125.6 to 98.8 at 6 months. Nickel cellular content increased from 0.52 to 0.68 and 0.78 ng per milliliter, and chromium increased from 0.31 to 0.41 and 0.78 ng per milliliter at 3 and 6 months, respectively. Compared with the control group, the treated subjects showed significant differences for DNA damage and chromium content at 3 months only. Fixed orthodontic appliances decreased cellular viability, induced DNA damage, and increased the nickel and chromium contents of the buccal mucosa cells. Compared to the control group, these changes were not evident at 6 months, possibly indicating tolerance for or repair of the cells and the DNA.