A finite element study comparing Advansync® and Twin Block in mandibular anterior repositioning.

OBJECTIVE: This study aims to utilize the finite element method (FEM) to compare the dentoalveolar and mandibular effects associated with anterior mandibular repositioning using AdvanSync® (ADV) and Twin Block (TB). METHODS: A patient with Class II skeletal malocclusion and mandibular retrognathism was selected. A TB appliance was subsequently applied. Computed Tomography (CT) scans were acquired at the beginning of treatment (T1) and 8 months later (T2). Concurrently, a numerical TB model was validated through FEM simulations, which were compared with the T2 results. The ADV appliance was virtually simulated to evaluate stress and deformation on the condyle, symphysis, first lower molar and lower central incisors. RESULTS: Both simulations demonstrated significant mandibular advancement. However, ADV led to less incisor proclination and more molar intrusion compared to TB. ADV exhibited increased stress in the lower molar area, while TB had higher stress in the lower incisor region. Stress and deformations in the condyle and mandibular symphysis were similar in both simulations, with the highest stress observed at the condylar neck and the lowest at the upper pole of the condylar head. CONCLUSIONS: Both appliances achieved similar levels of mandibular advancement, with greater proclination of the lower central incisors and more widespread distribution of stress and molar intrusion when using ADV compared to TB.

Quality of occlusal outcome in adult Class II patients treated with completely customized lingual appliances and Class II elastics compared to adult Class I patients.

OBJECTIVES: The aim of this investigation was to evaluate whether Class II malocclusion in adult patients can be successfully corrected using a completely customized lingual appliance (CCLA) in combination with Class II elastics. METHODS: In order to detect differences in the final treatment outcome, two groups were matched for age and gender. Treatment results of 40 adult orthodontic patients with a Class I malocclusion (Group 1) were compared to 40 adults with a Class II malocclusion (Group 2). All patients had completed treatment with a CCLA (WIN, DW Lingual Systems, Bad Essen, Germany) without known centric occlusion-centric relation discrepancies, issues of compliance, or overcorrection in the individual treatment plan which was defined by a target set-up. In order to compare the treatment results of the two groups, 7 measurements using the American Board of Orthodontics Model Grading System (ABO MGS) and linear measurements for anterior-posterior (AP) and vertical dimensions were assessed at the start of lingual treatment (T1), after debonding (T2B) and compared to the individual target set-up (T2A). RESULTS: A statistically significant AP correction was achieved in Group 2 which represented 95% of the planned amount. The planned overbite correction was fully achieved in the Class I and Class II group. In both groups, there was a statistically significant improvement in the ABO scores, with no significant difference between the two groups at T2. 100% of the patients in Group 2 and 92.5% in Group 1 would meet the ABO standards after CCLA treatment. LIMITATIONS: The main limitation of this study is that only patients who were wearing the elastics as prescribed were retrospectively included. Therefore, the results of this study may have limited generalizability. CONCLUSIONS: Completely customized lingual appliances in combination with Class II elastics can correct a Class II malocclusion successfully in adult patients. The final treatment outcome can be of a similar high quality in Class I and Class II patients.

Evaluation of the diagnostic ability of the Fränkel manoeuvre to detect the contributing jaw in angle class II division 1 malocclusion.

BACKGROUND: A correct diagnosis of patients with an Angle Class II malocclusion is needed to guide treatment decisions toward the contributing jaw and to achieve better treatment outcomes. The aim of the study is to evaluate the diagnostic potential of the Fränkel manoeuvre (FM) for detecting the components determining sagittal discrepancy in Angle Class II division 1. MATERIALS AND METHODS: Anonymous questionnaires containing photographs were distributed totwo groups: general practitioner (GP) dentists and orthodontists. The level of the patient's profile aesthetics before (T0) and after (T1) the manoeuvre was determined using a 100 mm visual analog scale, and the 'profile improvement' score was defined as T1 minus T0. The diagnostic ability of the FM was calculated by comparison with lateral cephalometry as a reference standard using receiver operating characteristic (ROC) curve analysis. RESULTS: A total of 102 respondents participated in the survey; 40 were orthodontists, and 62 were GP dentists. According to the post-FM images, the "profile improvement" score (T1-T0) was significantly greater in patients with mandibular retrusion than in those with maxillary protrusion (p < 0.05). The predictive power of FM, coinciding with the area under the ROC curve, was 0.62 for GPs and 0.78 for orthodontists. CONCLUSIONS: The FM method is a useful and accurate tool for diagnosing skeletal Angle Class II malocclusion etiology (mandibular retrusion or maxillary protrusion), especially when used by orthodontists.

Comparative evaluation of the dentoalveolar effects of three Class II correctors: A finite element analysis study.

OBJECTIVE: To compare the stress distribution and total strain applied to the dentition, periodontal ligament (PDL) and cortical and trabecular bones by three Class II correctors using finite element analysis. DESIGN: Three-dimensional analysis of stresses and total strain of the dentition with three Class II correctors. SETTING: Computational study. METHODS: Three-dimensional finite element models of Class II elastics, the Forsus Fatigue Resistant Device (FRD) and the Carriere Motion Appliance (CMA) were constructed from a cone-beam computed tomography (CBTC) image of an orthodontic Class II patient. The distribution of stress (von Mises and principal stress) and the total strain (mm) in maxillo-mandibular dentition, PDL, cortical and trabecular bone were analysed. RESULTS: The highest von Mises yield and the maximum principal stress in the three models were found at the teeth, followed by the cortical bone, trabecular bone and PDL. The maximum stress and total deformation were located at the upper canines and lower molars in the Class II elastics and CMA models, in the upper first molars in the Forsus FRD and CMA, and in the lower first premolars in the Forsus FRD. In addition, stress was distributed in the anterior and posterior regions of the teeth, and the total deformation was found in the distal direction in the upper arch and in the mesial direction in the lower arch. CONCLUSION: The stress concentrations in the three models were located close to the active components of each appliance, producing specific patterns of stress distribution and displacement that should be taken into account when planning the type of appliance to be used for the correction of the Class II malocclusion.

Evaluation of the stability of treatment with Herbst appliance associated with Hyrax expander and fixed orthodontics through counterpart analysis: A longitudinal follow-up study.

OBJECTIVE: The aim of this study was to evaluate the stability of treatment with a Herbst appliance associated with Hyrax expander (Stage I), followed by fixed appliances (Stage II) and follow-up for an average of 4 years after Stage II, on dentoskeletal facial structures. METHODS: This study involved 50 adolescents with Angle Class II division 1 malocclusion associated with mandibular retrognathism: Treated Group (TG-25) and Control Group (CG-25). Lateral cephalometric radiographs were taken: T1, immediately before Stage I (TG) or at the beginning of the follow-up period (CG); T2, at the end of Stage I (TG) or the follow-up period (CG); T3, at the end of Stage II (TG); and T4, on average, 4 years after Stage II (TG). Enlow's counterpart analysis and some cephalometric measurements were evaluated. Parametric and non-parametric tests were used (P ≤ 0.05). RESULTS: The ramus alignment variables (P < 0.001), SNB (0.040), ANB (<0.001), 1.PP (P = 0.015), 1.MP (P < 0.001), ms/RLp (P < 0.001), mi/RLp (P < 0.001) and S-LS (P = 0.005) showed differences between TG and CG from T1 to T2. Longitudinally, there were differences in ramus alignment, P = 0.003, T1 > T2 < T3 = T4; SNB, P = 0.016, T1 < T2 = T3 = T4; ANB, P < 0.001, T1 > T2 = T3 = T4; 1.MP, P < 0.001, T1 < T2 = T3 = T4; ms/RLp, P = 0.002, T1 = T2 < T3 = T4; mi/RLp, P < 0.001, T1 < T2 = T3 = T4; S-LS, P < 0.001, T1 > T2 = T3 = T4 and S-LI, P = 0.003, T1 = T2 = T3 > T4. CONCLUSION: The nasomaxillary complex (MCF/PM alignment) tended to a retrusive effect to compensate the degree of mandibular retrusion. The protrusive effect of the lower facial third was evident after the Herbst stage and did not remain stable in the follow-up. The dentoalveolar compensation and improvement in facial profile remained stable.

Finite element analysis of two skeletally anchored maxillary molar distalisation methods.

OBJECTIVE: To compare two methods of maxillary molar distalisation with skeletal anchorage using finite element analysis (FEA). METHODS: Two digitised models were created: the miniscrew-anchored distaliser, which consisted of a distalisation method anchored in a buccal miniscrew between the first molar and second premolar (Model 1), and the miniscrew-anchored palatal appliance, which consisted of a distalisation method anchored in a miniscrew on the anterior region of the palate (Model 2). FEA was used to simulate both methods, assessing teeth displacements and stress concentration. RESULTS: The miniscrew-anchored distaliser showed greater buccal than distal displacement of the first molar, while the opposite was observed in the miniscrew-anchored palatal appliance. The second molar responded similarly in the transverse and anteroposterior perspectives with both appliances. Greater displacements were observed at crown level than in apical regions. Greater stress concentration was observed at the buccal and cervical regions of the crown in the miniscrew-anchored distaliser and the palatal and cervical regions in the palatal appliance. The stress progressively spread in the buccal side of the alveolar bone for the miniscrew-anchored distaliser and in the palatal root and alveolar bone for the palatal appliance. CONCLUSION: FEA assumes that both appliances would promote maxillary molar distalisation. A skeletally anchored palatal distalisation force seems to provide a greater molar bodily movement with less undesirable effects. Greater stress is expected at the crown and cervical regions during distalisation, and the stress concentration in the roots and alveolar bone depends directly on the region the force was applied.

Timing of early correction of mandibular hypoplasia in skeletal class II malocclusion: a review.

Skeletal Class II malocclusion is a common malocclusion seen in clinics. It is characterized by maxillary protrusion and mandibular retrognathia and has a high incidence in adolescent mixed dentition and early permanent dentition. The early functional correction has achieved some clinical results in treating skeletal Class II malocclusion with mandibular hypoplasia. During treatment, the timing of correction is the key factor in determining the therapeutic effect, although it is difficult to understand. This review focuses on the timing of early correction of mandibular hypoplasia in combination with relevant assessment indicators and historical literature from four perspectives-the law of mandibular growth and development, the necessity of early treatment, the timing of early treatment, and the determination of the peak period of mandibular growth and development-to provide a theoretical reference for the timing of the treatment of clinical skeletal Class II malocclusion. This review shows that skeletal Class II mandibular growth has different characteristics in males and females. Bone growth assessment before treatment helps diagnose mandibular developmental morphology and the timing of early correction in adolescents with skeletal Class II malocclusion and hypoplasia of the mandible.

Class II treatment effects with fixed functional appliances: Jasper jumper vs. Forsus fatigue resistant device.

OBJECTIVE: This study aimed to compare cephalometric changes of Class II malocclusion patients treated with Jasper Jumper and Forsus, associated with fixed appliances. METHODS: The sample consisted of 62 individuals divided into 3 groups: group 1 included 22 subjects with a mean initial age of 12.39 years, treated with Jasper Jumper associated with fixed appliances for a mean period of 2.43 years; group 2 included 19 subjects with a mean initial age of 12.43 years, treated with Forsus associated with fixed appliances for a mean period of 3.54 years; and group 3 included 22 Class II malocclusion untreated subjects at a mean age of 12.14 years, followed for a mean period of 1.78 years. Intergroup comparison was performed with one-way ANOVA, followed by Tukey test. RESULTS: Both treated groups had similar dentoskeletal changes: restrictive effect on the maxilla; clockwise rotation of the occlusal plane; mild increase in lower anterior facial height; limitation on the vertical development of the maxillary molars; labial tipping and intrusion of the mandibular incisors; extrusion of mandibular molars; improvements of the maxillomandibular relationship, overjet, overbite, molar relationship; and retrusion of the upper lip. The mandibular incisors exhibited greater protrusion in group 1 compared to the other groups. In addition, group 2 presented mild protrusion of the lower lip, and groups 1 and 3 showed mild retrusion. CONCLUSION: The Jasper Jumper and Forsus appliances were effective and showed similar changes in the treatment of Class II malocclusion.

Malocclusion characteristics amongst individuals with autism spectrum disorder: a systematic review and meta-analysis.

BACKGROUND: To estimate the prevalence of malocclusion in individuals with autism spectrum disorders (ASD) and to assess the relationship between ASD and malocclusion. METHODS: We searched electronic databases including PubMed, Scopus, Web of Science, Cochrane, Embase, SciELO LILACS, Proquest, OpenGrey and Google Scholar. There were no language or publication dates restrictions. Two researchers independently performed selection, data extraction and quality assessment. Quality assessment and risk of bias were evaluated through the Newcastle-Ottawa scale and ROBINS-E tool. Meta-analyses using random effect models were used to estimate pooled measures of prevalence of malocclusion characteristics in individuals with ASD and pooled odds ratio (OR) on the relationship between ASD and malocclusion characteristics. Subgroup meta-analyses were conducted according to children and adolescents, history of orthodontic treatment, and occurrence of other syndromes and medical conditions. RESULTS: Searching identified 5549 papers with 238 were selected for full assessment. Eighteen cross-sectional studies were included according to inclusion criteria. Of them, eleven studies were considered of moderate quality. A judgement of critical risk of bias occurred for thirteen studies. The most prevalent malocclusion characteristics in individuals with ASD were crowding (33%; 95% CI 22 to 44%) and increased maxillary overjet (39%; 95% CI 23 to 54%). Individuals with ASD had higher odds of Angle's Class II (OR 1.92; 95% CI 1.36 to 2.72), Angle's Class III (OR 2.33; 95% CI 1.29 to 4.23), open bite (OR 1.96; 95% CI 1.21 to 3.16), and increased maxillary overjet (OR 1.53; 95% CI 1.06 to 2.21) than individuals without ASD. CONCLUSIONS: Angle's Class II, Angle's Class III, anterior open bite and increased maxillary overjet were more prevalent in individuals with ASD than those without ASD. Further high-quality studies are needed.

Skeletally anchored forsus fatigue resistant device for correction of Class II malocclusions-A systematic review and meta-analysis.

The use of skeletal anchorage with fixed functional appliances (FFA) has been proposed by various authors to produce skeletal changes and reduce lower incisor proclination. To compare the skeletal and dentoalveolar effects of Forsus Fatigue Resistant Device (FFRD) with or without skeletal anchorage (miniplates and mini-implants). The electronic database PubMed, Cochrane Library, Medline, Embase and Google Scholar along with a manual search of orthodontic journals till the year 2019. Only randomized control trials (RCTs) were included in the systematic review. One controlled clinical trial (CCT) which involved FFRD was included in the review since it was a continuation of an RCT which was expanded to a CCT. Skeletal and dentoalveolar outcome data were extracted to collect study characteristics. After evaluating risk of bias, the standardized mean differences (SMDs) and 95% confidence intervals (CIs) were calculated. Three RCTs and one prospective CCT were evaluated. The analysis included data from 116 Class II subjects [(58) treated with FFA along with skeletal anchorage and (58) treated with FFA]. There were no significant difference between the two groups with respect to mandibular length changes (P value = .10) and SNB angle changes (P value = .22). With respect to lower incisor inclination however, there was a significant difference between the two groups (P value = .005) signifying better results with respect to skeletal anchorage. The studies reviewed provide insufficient evidence to form a conclusion regarding the effects of the use of skeletal anchorage with FFRD. The available weak evidence suggests that the use of skeletal anchorage with FFRD has no superior skeletal effects but is able to reduce proclination of the lower incisors. Control of lower incisor proclination remains the most significant advantage of skeletal reinforcement, and miniplate-anchored FFRD showed more promising results in preventing lower incisor proclination than miniscrew-anchored FFRD.

Class II Division 1 malocclusion treatment with extraction of maxillary first molars: Evaluation of treatment and post-treatment changes by the PAR Index.

OBJECTIVE: To investigate occlusal result and post-treatment changes after orthodontic extraction of maxillary first permanent molars in patients with a Class II division 1 malocclusion. SETTING AND SAMPLE: Retrospective longitudinal study in a private practice, with outcome evaluation by an independent academic hospital. Ninety-six patients (53 males, 43 females) consecutively treated by one orthodontist with maxillary first permanent molar extraction were studied, divided into three facial types, based on pre-treatment cephalometric values: hypodivergent (n = 18), normodivergent (n = 21) and hyperdivergent (n = 57). METHODS: Occlusal outcome was scored on dental casts at T1 (pre-treatment), T2 (post-treatment) and T3 (mean follow-up 2.5 ± 0.9 years) using the weighted Peer Assessment Rating (PAR) Index. The paired sample t test and one-way ANOVA followed by Tukey's post hoc test were used for statistical analysis. RESULTS: PAR was reduced by 95.7% and 89.9% at T2 and T3, respectively, compared with the start of treatment. The largest post-treatment changes were found for overjet and buccal occlusion. Linear regression analysis did not reveal a clear effect (R-Square 0.074) of age, sex, PAR score at T1, incremental PAR score T2-T1, overjet and overbite at T1, and facial type on the changes after treatment (incremental PAR score T3-T2). CONCLUSIONS: The occlusal outcome achieved after Class II division 1 treatment with maxillary first permanent molar extractions was maintained to a large extent over a mean post-treatment follow-up of 2.5 years. Limited changes after treatment were found, for which no risk factors could be discerned.

Effects of surgical mandibular advancement on the upper airways of adult class II patients: A systematic review with meta-analysis.

AIM: To systematically review the effects of surgical mandibular advancement (SMA) regarding changes of the upper airways in adult patients with skeletal Class II malocclusion. MATERIALS AND METHODS: Five electronic databases were searched up to April 2020. Human studies focusing on the morphology and dimension of the upper airways after SMA were included. 'Quality assessment for Before-After (Pre-Post) Studies' was used to assess the risk of bias of the individual studies. Standard mean differences (SMD) with 95% confidence intervals (CI) were calculated for random effect model meta-analysis. The certainty of evidence was assessed using the GRADE tool. RESULTS: Twenty cohort studies of only treated patients without control group were eligible for qualitative synthesis, of which 17 were used for quantitative synthesis. Very low certainty of evidence indicated that SMA resulted in significant increase of the volume and of the smallest cross-sectional area (SMC) of the nasopharynx (volume SMD: 1.43, CI: 0.62, 2.24, P = .001, I2  = 87.8%; SMC SMD: 1.53, CI: 0.59, 2.47, P = .001, I2  = 90.5%) and oropharynx (volume SMD: 1.36, CI: 0.37,2.35, P = .007, I2  = 92.1%; SMC SMD: 1.21, CI: 0.11,2.32, P = .032, I2  = 93.1%). Significant augmentation of the distances between the posterior pharynx wall and the uvala (SMD: 0.73, CI: 0.46,0.98, P < .001, I2  = 72.7%), the posterior border of the tongue (SMD: 0.52, CI: 0.21,0.84, P = .001; I2 : 60.5%), the gonion (SMD: 1.24, CI: 0.56,1.91, P < .001; I2  = 88.8%) and the epiglottis (SMD: 0.40, CI: 0.06,0.74, P = .033; I2  = 84.8%) were observed. CONCLUSIONS: Weak evidence suggests enlargement of the upper airways of adult Class II subjects following SMA, with major increases in the oropharynx.

Comparison of Tooth Widths, Arch Widths and Arch Lengths in Class-I Normal Dentition to Class-I and II Crowded Dentitions.

BACKGROUND AND OBJECTIVE: Dental study casts play a vital role in the diagnosis and treatment planning of various orthodontic cases. This study was carried out to compare the tooth widths, arch widths, and arch lengths in Class-I normal dentition to those in Class-I and Class-II crowded dentition in an effort to improve treatment planning and to eventually reduce treatment duration. METHODS: Total 170 patients, 12 to 40 years of age with a complete set of permanent teeth till 1st molars; who presented to the Orthodontics Department at Armed Forces Institute of Dentistry (A.F.I.D), Rawalpindi from Sep 2019 to Feb 2020, were included in the study. Non-probability purposive method of sampling was used. The dental casts obtained were used to measure tooth widths, arch widths, and arch lengths. Subjects were classified into Class-I normal and Class-I and Class-II crowded occlusion and comparison of the sum of tooth widths, arch widths, and arch length discrepancies were determined among the three occlusion groups. Data was analyzed in SPSS version 21 and independent samples t-test was used to differentiate the variables of interest. RESULTS: Out of 170 subjects, 73 (42.9%) subjects had Class-I normal occlusion while 97 (57%) had Class-I and Class-II crowded occlusions. No statistical difference was found between the occlusal groups with regard to the sum of tooth widths, inter-canine widths, inter-first premolar widths, inter-second premolar widths and inter-molar widths. However, a remarkable difference was observed between the occlusal groups with respect to arch perimeters and arch length discrepancies (p = 0.000 and 0.000 respectively). CONCLUSIONS: Results of the current study indicate that crowding of teeth occurs as a consequence of decreased arch perimeters which may lead to increased arch length discrepancies. However, no prominent difference was noticed in the sum of tooth widths and arch widths among different occlusal groups.

Three-dimensional comparison of the skeletal and dentoalveolar effects of the Herbst and Pendulum appliances followed by fixed appliances: A CBCT study.

OBJECTIVES: To compare three-dimensional (3D) skeletal and dentoalveolar effects of the Herbst and Pendulum appliances followed by fixed orthodontic treatment in growing patients. SETTING AND SAMPLE POPULATION: A sample of 35 adolescents with cone-beam computed tomography scans obtained prior to Herbst and Pendulum treatment (T1) and immediately after fixed appliance treatment (T2). MATERIALS AND METHODS: Patients with Class II malocclusion was assessed retrospectively and divided into two treatment groups: Herbst group (n = 17, age: 12.0 ± 1.6 years) and Pendulum group (n = 18, age: 12.1 ± 1.5 years), with a mean treatment duration of 2.8 ± 0.8 years and 2.5 ± 0.7 years, respectively. Reconstructions of the maxillomandibular and dentoalveolar regions and data in 3D were obtained relative to cranial base, maxillary and mandibular regional superimpositions. Treatment outcomes (T2-T1) were compared between both groups using t tests for independent samples (P<.05). RESULTS: Significant increase in mandibular length was observed in the Herbst group (7.3 ± 3.5 mm) relative to the Pendulum group (4.6 ± 4.5 mm). Inferior and anterior displacements of Pogonion were 2.2 mm and 1.6 mm greater in the Herbst group, respectively. The mesial displacement of the lower first molars was significantly greater in the Herbst group (1.9 mm). The upper first molars had contrasting results in sagittal displacement, with 0.6 ± 1.7 mm of distal displacement with the Pendulum and 1.4 ± 2.1 mm of mesial displacement with the Herbst. Lower incisor projection and proclination were similar between groups. CONCLUSIONS: The Herbst and Pendulum appliances followed by comprehensive orthodontic treatment effectively corrected Class II malocclusion in growing patients, but with differing skeletal and dentoalveolar effects.

Condyle-glenoid fossa relationship after Herbst appliance treatment during two stages of craniofacial skeletal maturation: A retrospective study.

OBJECTIVES: To perform a three-dimensional evaluation of the position of the condyles in patients treated with Herbst appliance (HA) in two stages of cervical vertebral maturation. SETTING AND SAMPLE POPULATION: Retrospective case-control study. Pubertal Herbst group (PHG; n = 24, mean age 14.5 years, CS 3 and CS 4) and pre-pubertal Herbst group (PPHG; n = 17, mean age 9.9 years, CS 1 and CS 2) were contrasted with comparison groups of non-orthopaedically treated Class II patients in pubertal (PCG; n = 17, mean age 13.9 years) and pre-pubertal maturational stages (PPCG; n = 18, mean age 10.6 years). MATERIALS AND METHODS: Cone-beam computer tomography scans were taken before treatment (T0) and at T1 after 8 to 12 months. Point-to-point measurements of the displacement of the condyles between T0 and T1, relative to the glenoid fossae, were performed in the X, Y, Z and 3D perspectives. Qualitative assessments using semi-transparent overlays and colour mapping also were produced. RESULTS: The displacement of the condyles within the glenoid fossae in the treated groups was small (<0.75 mm; P > .05). Relative to the glenoid fossa, condylar position at T1 was similar to T0 in pre-pubertal and pubertal groups (P > .05). Similar condylar rotations from T0 to T1 were observed in Herbst and comparison groups, and no significant difference was found between pre-pubertal and pubertal patients. CONCLUSIONS: Regardless the stage of skeletal maturation, HA treatment did not change the condyle-glenoid fossa relationship.

Class II functional appliance treatment and dynamic three-dimensional mimic muscle evaluation.

BACKGROUND: Functional appliances have skeletal and dentoalveolar treatment effects, but knowledge on their effect on facial expressions is limited. OBJECTIVE: To analyse changes in facial expressions, using three-dimensional (3D) mimic muscle evaluation, in growing children with Class II malocclusion and large overjet, undergoing functional appliance treatment. METHODS: Fifteen growing children with Class II division 1 malocclusion, selected prospectively, had dynamic 3D recordings of facial expressions prior to and 12 months after commencing functional appliance treatment. Facial expressions recorded were smile and lip pucker, and the movements of the oral commissures were analysed, as well as mouth width and its symmetry. A control group of fifteen age- and sex-matched growing children without immediate need for orthodontic treatment had similar recordings prior to and after a 12-month observation period. RESULTS: In the treatment group, the Class II malocclusion in all children improved after 12 months of functional appliance wear. With regard to movements of the oral commissures, the initial recordings of the treatment group did not show any significant differences to the control group for neither smile nor lip pucker. Differences were noted however when looking at mouth width asymmetry, where this tended to become more symmetrical in the functional appliance treatment group, during rest and during smiling, while it became more asymmetrical in the untreated control group. CONCLUSION: The use of removable functional appliances in children with Class II division 1 malocclusion may have a positive effect on mouth width symmetry when smiling, making it more symmetrical.

Impact of molar teeth distalization with clear aligners on occlusal vertical dimension: a retrospective study.

BACKGROUND: A common strategy in the non-extraction treatment of Class II molar relationship is maxillary molar distalization, which could increase lower face height and cause clockwise mandibular rotation. The aim of this retrospective study was to analyse the effects on vertical dentoskeletal dimension of young adults treated with sequential distalization with orthodontic aligners. METHODS: Lateral cephalometric radiographs of 10 subjects (8 females 2 males; mean age 22.7 ± 5.3 years) treated with upper molars sequential distalization with orthodontic aligners (Invisalign, Align Technology, San Josè, California, USA) were analyzed. RESULTS: No statistically significant difference was observed for the primary outcome SN-GoGn between T0 and T1 and it was recorded a mean variation of 0.1 ± 2.0 degrees. Statistically significant differences were found in the linear position of the upper molars (6-PP, 7-PP) the molar class relationship parameter (MR) and the upper incisive inclination (1^PP) with at least p < 0.01. CONCLUSIONS: Upper molar distalization with orthodontic aligners guarantee an excellent control of the vertical dimension representing an ideal solution for the treatment of hyperdivergent or openbite subjects. It also allows an excellent control of the incisal torque without loss of anchorage during the orthodontic procedure.

A Review on Comparison of Tooth Size Discrepancies among Angle's Class I, II, and III Malocclusion: Is There a Significance?

AIM: The contemporary article aims to review and compare various literatures concerning different conclusions regarding the correlation between tooth size discrepancy (TSD) and Angle's malocclusion groups. BACKGROUND: Acquiring the ideal occlusion plays one of the major roles while designing the treatment plan for an orthodontic patient, any alterations in the individual tooth sizes are called TSD and will hinder this prime requirement. By determining the correct tooth size ratio, it further helps in acquiring the accurate interdigitation, balanced occlusion, and also predicting the orthodontic treatment results. Various investigations were carried out to know the correlation between tooth size discrepancies and different malocclusion groups, of which, a few reported a statistically significant difference whereas others reported no significant difference. REVIEW RESULTS: A computerized database quest was operated utilizing the Medline database (Pubmed/Medline) for original research and review articles. Publications between 1946 and 2018 were included. Four hundred twenty-one articles were recovered from database search and, among them, 66 articles were selected to review the full-article. CONCLUSION: Although a comparison was done between the tooth-size ratios and malocclusion groups (classes I, II, and III), many investigators noted no significant difference but there is an inadequacy in the data particularly related to subgroups of Angle's classification of malocclusion among these investigations; therefore, further studies are required to interpret this correlation. CLINICAL SIGNIFICANCE: As there is high incidence of tooth size discrepancies noted in the previous literature orthodontist, Bolton's analysis regardless of malocclusion group, sex, and ethnicity is highly recommended.

EMG-characteristic of masticatory muscles in patients with class II malocclusion and temporomandibular disorders.

OBJECTIVE: Introduction: A stable state of musculoskeletal system is provided by harmony of occlusion, the anatomy of temporomandibular joints, and the activity of the masticatory muscles under the control of peripheral and central nervous system. Surface electromyography (EMG) is a well-used modality and is used in dentistry to access the status of the muscles of mastication. The aim of the research was to evaluate the EMG-characteristic of masticatory muscles in patients with TMD and Angle Class II malocclusion. PATIENTS AND METHODS: Materials and methods: The study comprised 23 patients with Angle Class II malocclusion and TMD. The average age of the subjects was 26,5 ± 2,3 years. Malocclusion was evaluated according to Angle classification, TMD - according to the Research Diagnostic Criteria (RDC/TMD). Registration of EMG-activity of masseter and anterior temporalis muscles was performed during maximum voluntary clenching, clenching on the right and left sides. RESULTS: Results: EMG-activity of masticatory muscles are characterized by: 1) increased values of EMG-activity of temporal and masseter muscles - peak and average amplitude in tests of unilateral clenching and maximum clenching (values are greater than 2000 µV); 2) in unilateral clenching of jaws (on the left or right) the increased EMG-activity was detected on the balancing side; 3) in unilateral clenching of jaws (on the left or right) the increased muscle activity on the working side with disproportional (asymmetric) load distribution between masseter and temporal muscles has been found. CONCLUSION: Conclusions: Patients with Angle Class II malocclusion and TMD were found features of EMG-activity of masticatory muscles.

Temporomandibular joint positional change accompanies post-surgical mandibular relapse-A long-term retrospective study among patients who underwent mandibular advancement.

OBJECTIVE: This study evaluated the relationship between follow-up temporomandibular joint positional change and mandibular stability among patients who had orthognathic and orthodontic treatment for a skeletal Class II malocclusion. METHODS: Thirty-seven patients who underwent 2-jaw surgery (Le Fort I osteotomy, bilateral sagittal split ramus osteotomy and genioplasty with rigid internal fixation) were included with an average follow-up length of 8.10 ± 2.06 years. They were categorized into a stable and unstable group according to follow-up mandibular change in the sagittal direction. Temporomandibular joint spaces were measured on serial magnetic resonance images, prior to orthodontic treatment (T0), upon completion of orthodontic treatment following surgery (T1), and at least 5 years post-completion of the treatment (T2). RESULTS: While the maxillary position was stable during the follow-up period, the mandibular positional change was statistically significant (the relapse amount was -0.81 ± 1.52 mm at B point). An increase in the anterior joint space and superior joint space was found to correlate with the follow-up mandibular backward movement. CONCLUSIONS: Patients who underwent orthognathic and orthodontic treatment to correct mandibular retrognathism displayed follow-up mandibular relapse in the sagittal direction. The relapse is accompanied by condylar positional change.