Effects of fixed functional appliance treatment on the temporomandibular joint

Three-dimensional volumetric analysis of the temporomandibular joint space using a standard conical object

OBJECTIVE

The objective was to present a novel method for the assessment of the temporomandibular joint space volume (TMJSV) in cone beam computed tomography (CBCT) examinations with TMJ region landmarks. The significance of differences in measurements of mandibular head width (MHW) and volume (MHV) as well as TMJSV was calculated comparing right vs. left sides and males vs. females.

STUDY DESIGN

CBCT images from 50 Angle Class I adults were evaluated using 3D image software. MHW and MHV were obtained from each TMJ. The representative TMJSV was found through Boolean subtraction using a standard conical object in .stl format. Paired t-tests were used to compare right and left sides. The Pearson correlation coefficient was used to assess the correlation between numerical variables. Student t-tests were used to compare MHW, MHV, and TMJSV between males and females. P < .05 indicated significant difference.

RESULTS

The right and left mean MHW, MHV, and TMJSV values were 19.46 and 19.47 mm, 1431.51 and 1401.39 mm3, and 475.51 and 461.13 mm3, respectively, with no significant differences between sides (P ≥ .381). Correlation of these measurements with ipsilateral and contralateral values was moderate to strong (.70 - .89). Males presented higher mean values for all measurements (P ≤ .023).

CONCLUSIONS

The results are comparable to those of other studies, indicating the reliability of our method as a nuanced analysis of the intricate TMJ anatomy.

In vitro evaluation of cytotoxicity of fixed functional appliances

OBJECTIVE

The objective of this study was to evaluate the cytotoxicity of fixed functional appliances that are commonly used in the treatment of Class II malocclusion caused by mandibular retrognathia, using the MTT cell viability assays [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] (Sigma Chemical Co., Milan, Italy).

MATERIALS AND METHODS

The cytotoxicity of five different fixed functional appliances commonly used in orthodontic treatments was assessed. The appliances evaluated included Jasper Jumper (American Orthodontics, Wisconsin, USA), Power Scope (American Orthodontics, Wisconsin, USA), Herbst (American Orthodontics, Wisconsin, USA), Forsus™ Fatigue Resistant Device Kits (3 M, MN, USA), and Twin Force Bite Corrector (Henry Schein Orthodontics, California, USA). Assays were conducted using one appliance from each type, resulting in a total of seven groups. Cytotoxicity testing was performed using the MTT assay on a human gingival fibroblast (HGF) cell line. Data analysis was conducted using the Kruskal-Wallis test with a significance level of p = 0.05.

RESULTS

All appliances demonstrated cell viability rates exceeding 90%, categorizing them as non-cytotoxic under ISO 10993-5 standards. Herbst exhibited the highest proliferation index (2.62 ± 1.13), while Power Scope (2.05 ± 1.06) and Jasper Jumper (1.90 ± 1.23) showed the lowest indices. Despite these variations, statistical analysis revealed no significant cytotoxic effects when compared to the control group (p > 0.05). All appliances were confirmed as biologically safe for cell health.

CONCLUSION

The findings demonstrate that all evaluated appliances exhibit a biocompatible interaction with HGF cells, with no evidence of adverse cytotoxic effects. These results support the safe clinical use of these fixed functional appliances in orthodontic treatment.

Quantification of temporomandibular joint space in patients with juvenile idiopathic arthritis assessed by cone beam computerized tomography

OBJECTIVE

To describe a method to calculate the total intra-articular volume (inter-osseous space) of the temporomandibular joint (TMJ) determined by cone-beam computed tomography (CBCT). This could be used as a marker of tissue proliferation and different degrees of soft tissue hyperplasia in juvenile idiopathic arthritis (JIA) patients.

MATERIALS AND METHODS

Axial single-slice CBCT images of cross-sections of the TMJs of 11 JIA patients and 11 controls were employed. From the top of the glenoid fossa, in the caudal direction, an average of 26 slices were defined in each joint (N = 44). The interosseous space was manually delimited from each slice by using dedicated software that includes a graphic interface. TMJ volumes were calculated by adding the areas measured in each slice. Two volumes were defined: Ve-i and Vi , where Ve-i is the inter-osseous space, volume defined by the borders of the fossa and Vi is the internal volume defined by the condyle. An intra-articular volume filling index (IF) was defined as Ve-i /Vi , which represents the filling of the space.

RESULTS

The measured space of the intra-articular volume, corresponding to the intra-articular soft tissue and synovial fluid, was more than twice as large in the JIA group as in the control group.

CONCLUSION

The presented method, based on CBCT, is feasible for assessing inter-osseus joint volume of the TMJ and delimits a threshold of intra-articular changes related to intra-articular soft tissue proliferation, based on differences in volumes. Intra-articular soft tissue is found to be enlarged in JIA patients.

Comparison of Skeletal Changes in the Temporomandibular Joint between the Twin Block Appliance and Fixed Functional Appliance: A Longitudinal Follow-up Study

Aim

This current study evaluated and compared the skeletal changes in the head of the condyle, glenoid fossa, and articular space between the twin block appliance and PowerScope™ a fixed functional appliance.

Materials and methods

This study was a pilot, randomized, single-blinded, assessing the skeletal changes in the components of the temporomandibular joint (TMJ) using cone-beam computed tomography (CBCT). The study was conducted in 20 subjects in the age range of 11-14 years with class II division 1 malocclusion. These subjects were distributed randomly between two groups with an allocation ratio of 1:1 (group I-twin block and group I-PowerScope™). Follow-ups of both groups were done till desirable skeletal correction was attained (clinical edge-to-edge incisor relation).

Results

Condylar parameters such as position, height, and length were evaluated bilaterally in the CBCT scans. After using both devices, there was an increase in all condylar qualities; however, the twin block appliance showed a more noticeable difference, which has been determined to be statistically significant. In the twin block group, there was an average decrease of 0.56 mm in the anterior articular space and an increase of 1.2 and 2.64 mm in the middle and posterior articular spaces, respectively. In the PowerScope™ group, there was an average decrease of 0.23 mm in the anterior articular space and an increase of 2.55 and 1.85 mm in the middle and posterior articular spaces, respectively. In the case of the twin block device, the change in glenoid fossa angle was observed to be 6.1 mm on both sides and a mean difference of 1.25 mm on the right-side and 1.75 mm on the left-side was observed in the case of PowerScope™. The difference was established to be significant with a p < 0.05 in all cases.

Conclusion

Condylar attributes increased after the application of both devices but the difference was more pronounced in the case of twin block appliances. The difference in articular space (middle and posterior) between the twin block group and PowerScope™ group, was not significant statistically. In the present study, the remodeling in the glenoid fossa was greater in the twin block group compared to the PowerScope™ group.

How to cite this article

Halapanavar B, MN P, Deshmukh S, et al. Comparison of Skeletal Changes in the Temporomandibular Joint between the Twin Block Appliance and Fixed Functional Appliance: A Longitudinal Follow-up Study. Int J Clin Pediatr Dent 2024;17(1):7-14.

Impact of molar teeth distalization by clear aligners on temporomandibular joint: a three-dimensional study

BACKGROUND

Maxillary molar distalization is a common technique used in the non-extraction treatment of Angle Class II malocclusion that can effectively correct the molar relationship and create spaces for anterior teeth alignment. However, this approach may also impact the temporomandibular joint (TMJ) due to predictable changes in the posterior vertical dimension. Despite its widespread use, Class II malocclusions correction by molar distalization with clear aligners has not been investigated for their effects on the TMJ. Therefore, this study aimed to analyze the impact of sequential molar distalization using clear aligners on the TMJ.

METHODS

Three-dimensional CBCT scans of 23 non-growing patients (7 males, 16 females; mean age 29.8 ± 4.6 years) with skeletal class I or II malocclusion and a bilateral molar class II relationship treated by sequential upper molars distalization with orthodontic clear aligners (Invisalign, Align Technology, San Josè, Ca, USA). A total of 46 joints were examined before and after molar distalization using Anatomage InvivoDental 6.0.3. Linear and angular measurements of the mandibular joint were measured, including joint parameters, inclination, position, and the dimension of the condyle and articular fossa. In addition, 3D volumetric spaces of the joint were analyzed. All data were statistically analyzed by paired T test to determine the differences between the pre-and post-orthodontic procedures.

RESULTS

No statistically significant differences were found in all primary effects resulting from maxillary molars distalization by clear aligners on TMJ components measurements and joint spaces between T0 and T1. Meanwhile, statistically significant differences were observed in the linear position of the upper molars and the molar relationship parameter with at least P ≤ 0.05.

CONCLUSION

Treatment by sequential upper molars distalization with clear aligners does not lead to significant TMJ parameters changes in condyle and fossa spaces, dimensions, and positions.

Role of orthodontic tooth movement on temporomandibular joint: An original research

Introduction:

Orthodontic treatment may bring about changes in the temporomandibular joint (TMJ) disc. Hence, we aim to assess the impact of the orthodontic tooth movement on the articular disc repositioning of TMJ.

Materials and Methods:

We conducted an observational prospective study among 50 class IIdiv-I subjects. The magnetic resonance images were used to evaluate TMJ during the orthodontic treatments. The phases were T1-start of treatment, T2-thru phase I, T3-at the end of phase I, and T4-at the end of phase II. The qualitative values were compared for the disc changes.

Results:

No significant changes in the disc position or the regression were seen with open or closed mouth between T1-T3, T3-T4, and T1-T4. Significant variation for the position of the disc was seen in the opened mouth between T3-T4. Significant variation for the form of the disc was seen when closed at T1-T2 and T2-T3.

Conclusions:

Disc of the TMJ maintained the form and position during the treatments.

A comparison of the effects of Forsus appliances with and without temporary anchorage devices for skeletal Class II malocclusion

OBJECTIVES

To compare the effects of Forsus appliances with and without temporary anchorage devices (TADs) for patients with skeletal Class II malocclusion.

MATERIALS AND METHODS

Through a predefined search strategy, electronic searching was conducted in PubMed, Embase, Web of Science, CENTRAL, ProQuest Dissertations & Theses, and SIGLE with no language restrictions. Eligible study selection, data extraction, and evaluation of risk of bias (Cochrane Collaboration tool) were conducted by two authors independently and in duplicate. Any disagreement was solved by discussion or judged by a third reviewer. Statistical pooling, sensitivity analysis, subgroup analysis, and assessment of small-study effects were conducted by using Comprehensive Meta-Analysis and Stata 12.0. Heterogeneity was analyzed for different types of study designs, TADs, and radiographic examinations.

RESULTS

Electronic search yielded a total of 256 studies after removing duplicates. Among them, six studies were finally included. All articles were of high quality. The pooled mean differences were -0.27 (95% confidence interval [CI]: -0.59, 0.05) for SNA, 0.58 (95% CI: -0.07, 1.23) for SNB, -0.86 (95% CI: -1.74, -0.03) for ANB, 1.63 (95% CI: 0.46, 2.80) for Co-Po, 0.75 (95% CI: 0.28, 1.23) for SN-MP, -7.56 (95% CI: -11.37, -3.76) for L1-MP, 0.47 (95% CI: -0.98, 1.91) for overjet, 0.39 (95% CI: -0.57, 1.35) for overbite, -1.84 (95% CI: -5.15, 1.47) for SN-OP, and 4.97 (95% CI: -1.22, 11.17) for nasolabial angle.

CONCLUSIONS

TADs (especially miniplates) were able to eliminate dental adverse effects of Forsus appliances for correction of skeletal Class II malocclusion.

Treatment outcome and long-term stability of class II correction with forsus fatigue resistant device in non-growing patients

OBJECTIVES

Forsus™ Fatigue Resistant Device (FRD) is one of the commonly used semirigid fixed functional devices. Purpose of the present study was to investigate effects and long-term stability of Class II correction following use of Forsus FRD in a retrospective clinical study.

SETTING AND SAMPLE POPULATION

Records of 20 patients (mean age 18.3 ± 2.5 years) with Class II malocclusion, who had undergone fixed functional treatment protocol with Forsus FRD, were collected from our clinical archive.

MATERIALS AND METHODS

Lateral cephalometric radiographs at pre-treatment (T0), end of comprehensive treatment (T1) and post-retention period (T2, mean duration: 19 ± 3 months) were analysed and superimposed to assess skeletal and dental changes on the long-term. Repeated measurement one way ANOVA was used for the study of the significant differences among the mean values of cephalometric parameters at T0, T1, and T2. To analyse the nature of the bilateral significant differences between two different time points, Bonferroni test was used.

RESULTS

Sagittal and vertical skeletal changes at T0-T1 were statistically insignificant while all dentoalveolar parameters exhibited highly significant changes. At T1-T2, all skeletal and dentoalveolar parameters were stable except the slight relapse in overjet (0.3 ± 0.5 mm; P < .05). At T0-T2 interval, no significant skeletal changes were recorded while the dentoalveolar changes remained significantly improved.

CONCLUSION

Correction of Class II malocclusion achieved with Forsus FRD was dentoalveolar and treatment effects were stable in the 19 ± 3 months follow-up period.

Stability of Class II corrections with removable and fixed functional appliances: A literature review

BACKGROUND

Class II functional appliances have been used in orthodontics for over 100 years. Although the stability of corrections is one of the main goals of orthodontic treatment, there is a paucity of longitudinal studies on the long-term stability of treatment of Class II malocclusion based on functional appliances.

METHODS

This narrative review attempts to summarize the limited related evidence available and discusses the clinical implications of important aspects related to occlusal and skeletal changes that arise after Class II malocclusion treatment with functional appliances.

RESULTS

The occlusal changes obtained through Class II functional treatment do mostly exhibit long-term stability. While mild posttreatment changes occurred, they were most likely due to physiologic aging processes and not likely associated with actual treatment relapse. Long-term retention in the lower jaw would be particularly beneficial. A stable occlusion with good intercuspation in the posterior arches seems more likely to preserve a Class I occlusion after treatment through dentoalveolar compensatory mechanisms. After treatment, the maxilla and the mandible do grow anteriorly, with the mandible growing more than the maxilla. Patients treated with functional appliances are not likely to develop TMJ disorders over the long term.

CONCLUSIONS

Long term skeletal corrections achieved with functional appliances seem to be overall stable. Class II molar and overjet relapses can be likely explained by a combination of tooth movement and an unfavorable posttreatment maxillomandibular growth pattern, especially when combined with unstable interdigitation of the posterior teeth. No specific intermaxillary retention approach has been assessed yet.

Three-dimensional cone beam computed tomography analysis of temporomandibular joint response to the Twin-block functional appliance

Objective

To propose a three-dimensional (3D) method for evaluating temporomandibular joint (TMJ) changes during Twin-block treatment.

Methods

Seventeen patients with Class II division 1 malocclusion treated using Twin-block and nine untreated patients with a similar malocclusion were included in this research. We collected their cone beam computed tomography (CBCT) data from before and 8 months after treatment. Segmentations were constructed using ITK-SNAP. Condylar volume and superficial area were measured using 3D Slicer. The 3D landmarks were identified on CBCT images by using Dolphin software to assess the condylar positional relationship. 3D models of the mandible and glenoid fossa of the patients were constructed and registered via voxel-based superimposition using 3D Slicer. Thereafter, skeletal changes could be visualized using 3DMeshMetric in any direction of the superimposition on a color-coded map. All the superimpositions were measured using the same scale on the distance color-coded map, in which red color represents overgrowth and blue color represents resorption.

Results

Significant differences were observed in condylar volume, superficial area, and condylar position in both groups after 8 months. Compared with the control group (CG), the Twin-block group exhibited more obvious condyle-fossa modifications and joint positional changes. Moreover, on the color-coded map, more obvious condyle-fossa modifications could be observed in the posterior and superior directions in the Twin-block group than in the CG.

Conclusions

We successfully established a 3D method for measuring and evaluating TMJ changes caused by Twin-block treatment. The treatment produced a larger condylar size and caused condylar positional changes.

Evaluation of condyle-fossa relationships in adolescents with various skeletal patterns using cone-beam computed tomography

OBJECTIVES

To evaluate the condyle-fossa relationship in adolescents with various skeletal patterns using cone-beam computed tomography (CBCT).

MATERIALS AND METHODS

CBCT images obtained in 120 adolescent patients were used for this study. The patients were divided into 3 groups according to 3 criteria: (1) age (early, middle, and late adolescence); (2) facial height ratio or Jarabak quotient (hyperdivergent, normodivergent, and hypodivergent); and (3) ANB classification (Class I, Class II, and Class III). Temporomandibular joint space (TMJS: AS, anterior space; SS, superior space; PS, posterior space; MS, medial space; LS, lateral space), width and depth of the condyle (MLT, mediolateral thickness; APT, anteroposterior thickness), articular slope (ArS) and vertical height of the fossa (VHF) were measured and compared using CBCT.

RESULTS

Differences in condyle-fossa relationships were not significantly different between male and female adolescents, but were significantly different (P < .05) between left and right sides. The mean values showed no statistical differences according to age and skeletal pattern. Most measurements in the sagittal view showed that SS was the greatest, and the mean ratio of AS to SS to PS was 1.00 to 1.27 to 1.19, respectively. The mean values of coronal MS and LS were not significantly different.

CONCLUSIONS

There were almost no statistical differences in the TMJS in adolescents across various factors except between left and right sides.

Anterior open bite due to idiopathic condylar resorption during orthodontic retention of a Class II Division 1 malocclusion

A common dilemma when treating anterior open bite is understanding its etiology. Idiopathic condylar resorption (ICR) can cause open bite in affected individuals. Although it is prudent to not treat patients with ICR until active resorption has ceased, orthodontists may begin treating them because anterior open bite from ICR may not appear before or during their orthodontic treatment. This article reports a 12-year-old female who was diagnosed with ICR 10 months after completion of her orthodontic treatment for a Class II Division 1 malocclusion. When a young patient with a high mandibular angle and previous skeletal or dental Class II malocclusion returns with an open bite during the retention phase, the patient's condyles must be carefully examined to determine whether any temporomandibular joint disorder, such as ICR, is present. Currently, the controversy over the cause and the cure for ICR is continuing to challenge orthodontists in diagnoses and treatments. Orthodontists should closely monitor and offer informed treatment options to patients with risk factors for ICR or signs of its pathology that might develop at any stage of orthodontic treatment, including the retention period.

What effect does functional appliance treatment have on the temporomandibular joint? A systematic review with meta-analysis

BACKGROUND

The aim of the current systematic review was to compare the radiologic effects of functional appliance Class II treatment compared to no treatment on the temporomandibular joint and its components.

METHODS

Nine databases were searched up to June 2019 for randomized or prospective non-randomized clinical trials comparing Class II patients treated with functional appliances to untreated patients. After duplicate study selection, data extraction, and risk of bias assessment with the Cochrane tool and the ROBINS-I tool, random effects meta-analyses of mean differences (MDs) and their 95% confidence intervals (CIs) were performed, followed by the assessment of the quality of evidence with GRADE.

RESULTS

A total of 11 papers on 8 unique trials with 377 patients (39.8% male; average age 10.3 years) were finally included. Limited evidence indicated that compared to untreated growing patients functional appliance treatment was associated with increased condylar width (2 studies; MD 1.1 mm; 95% CI 0.1 to 2.2 mm; very low evidence quality), decreased anterior joint space (2 studies; MD - 0.7 mm; 95% CI - 0.5 to - 0.9 mm; very low evidence quality), increased superior joint space (2 studies; MD 0.7 mm; 95% CI 0.5 to 1.0 mm; very low evidence quality), increased posterior joint space (2 studies; MD 1.0 mm; 95% CI 0.9 to 1.2 mm; very low evidence quality), and vertical displacement of the glenoid fossa (2 studies; MD 0.4 mm; 95% CI 0.1 to 0.7 mm; very low evidence quality). The main limitations affecting the validity of the present findings were the inclusion of non-randomized studies with methodological issues, imprecision due to limited samples of the included studies, and inconsistencies among studies.

CONCLUSIONS

Currently existing evidence from controlled clinical studies on humans indicates that functional appliance treatment is associated with positional and skeletal alterations of the temporomandibular joint in the short term compared to untreated controls. However, the clinical relevance of these changes remains unclear, while the quality of existing evidence is low due to methodological issues of existing studies.

REVIEW REGISTRATION

PROSPERO, CRD42018109271.

Are morphologic and topographic alterations of the mandibular fossa after fixed functional treatment detectable on tomograms? Visual classification and morphometric analysis

AIM

The goal was to evaluate if changes in morphology and topography of the mandibular fossa after Functional Mandibular Advancer (FMA) treatment are detectable on tomograms. Furthermore, the suitability of digital tomograms (DT) over magnetic resonance imaging (MRI) for this particular question was investigated.

MATERIALS AND METHODS

In all, 25 patients (14 female, 11 male) with a skeletal class II malocclusion received treatment with a FMA. DTs were available prior to (T1) and after (T2) FMA treatment. A total of 50 temporomandibular joints were investigated. The mandibular fossae were evaluated metrically and visually regarding treatment-induced alterations. A p < 0.05 was set as the level for statistical significance for all tests. Results were compared to the results of a recent MRI study.

RESULTS

Visual inspection of all 50 joints in the DT at T1 and T2 revealed no alterations of the fossa shape in the sagittal plane; 24 patients showed identical morphology of right and left joints. The metrical analysis revealed no significant changes regarding width, depth and ratio thereof between T1 and T2. There also were no bilateral differences. Another 18 different distance measurements between porion, mandibular fossa, articular eminence and pterygoid fossa showed no significant changes. There was no detectable proof of a fossa shift.

CONCLUSIONS

No changes in the sagittal plane, mandibular fossa, the articular tubercle, or a possible fossa shift were found in the DT of class II patients after FMA treatment. DT and MRI measurements and the visual inspection revealed identical findings; thus, DT appears to be a valuable research tool for sagittal analysis of mandibular fossa changes.

Effects of skeletally anchored Class II elastics: A pilot study and new approach for treating Class II malocclusion

OBJECTIVE

To evaluate the skeletal, dentoalveolar, and soft tissue effects of skeletally anchored Class II elastics and compare them with a matched control group treated by a monobloc appliance for the correction of skeletal Class II malocclusion due to mandibular retrusion.

MATERIALS AND METHODS

Twelve patients (6 girls, 6 boys) were randomly divided into two groups. In the elastics group, six patients (12.9 ± 1.5 years of age; 3 boys, 3 girls) were treated with skeletally anchored Class II elastics. Two miniplates were placed bilaterally at the ramus of the mandible and the other two miniplates were placed at the aperture piriformis area of the maxilla. In the monobloc group (3 boys and 3 girls; mean age, 12.3 ± 1.6 years), patients used the monobloc appliance. The changes observed in each phase of treatment were evaluated using the Wilcoxon matched-pair sign test. Intergroup comparisons at the initial phase of treatment were analyzed by the Mann-Whitney U test.

RESULTS

There were statistically significant group differences in Co-Gn, B-VRL, U1-PP, U1-VRL, Ls-VRL, with significant increases in these parameters in the elastics group (P < .05). The mandibular incisors were protruded in the monobloc group (5.45 ± 1.23°), whereas they were retruded in the elastics group (-3.01 ± 1.66°; P < .01).

CONCLUSIONS

The undesirable dentoalveolar effects of the monobloc appliance were eliminated by using miniplate anchorage. Favorable skeletal outcomes can be achieved by skeletal anchorage therapies which could be an alternative to treat skeletal Class II patients with mandibular deficiency.

Pharyngeal airway effects of Herbst and skeletal anchored Forsus FRD EZ appliances

BACKGROUND AND OBJECTIVE

To evaluate the skeletal and pharyngeal airway effects of skeletal anchored Forsus FRD EZ appliance using bilateral miniplates inserted on mandibular symphyses and to compare the findings with a well matched control group treated using a Herbst appliance.

METHODS

Thirty patients with skeletal Class II malocclusion due to mandibular retrusion were divided into two groups. Group 1 consisted of 15 patients (8 females and 7 males; mean age: 13.11 ± 1.29 years) treated using the Herbst appliance and Group 2 consisted of 15 patients (9 females and 7 males; 12.84 ± 1.27 years) treated using the skeletal anchored Forsus FRD EZ appliance. Treatment changes were assessed by means of linear, angular, and area measurements.

RESULTS

The groups were well matched regarding to the chronological ages, gender distribution and initial cephalometric values (P > 0.05). In both groups, skeletal Class II malocclusion was corrected by decrease in SNA and increase in SNB, Co-Gn, VRL-B and VRL-Pog measurements. Those changes caused a significant correction in the maxillo-mandibular relationship. Upper and lower pharyngeal airway dimensions were increased in both group, while the increase in the lower pharyngeal dimension was found to be statistically significant in the skeletal anchored Forsus FRD EZ group (P < 0.05). Oropharyngeal area measurements significantly increased in both groups (P < 0.001 and P < 0.01, respectively). Comparison of the groups showed that both groups had similar changes with no statistically significant differences (P > 0.05).

CONCLUSION

Skeletal changes produced by both appliances caused significant pharyngeal airway changes.

Impact of functional mandibular advancement appliances on the temporomandibular joint - a systematic review

Background

Although many orthodontists have no doubts about the effectiveness of functional appliances for mandibular advancement, the impact on the temporomandibular joint (TMJ) is still in dispute. The objective of this systematic review is to examine the main effects on the TMJ of using functional appliances, both in healthy patients and in patients with a pre-existing disorder.

Material and Methods

A systematic review of the literature was conducted in accordance with the PRISMA guidelines. Only systematic reviews, meta-analyses, randomized clinical trials (RCTs), case-control studies and cohort studies were included. A detailed language-independent electronic search was conducted in the Pubmed, Scopus, Cochrane Library and Embase databases. All studies published between 2000 and 2015 were included.

Results

A total of 401 articles were identified. Of these, 159 were duplicates and were excluded. On reading the title and abstract, 213 articles were excluded because they did not answer the research question, leaving a total of 29 articles. These articles were read and assessed. Following critical reading of the full text, eight articles were excluded: seven because they were considered of low quality and one because it published redundant data. As a result, 21 articles were included.

Conclusions

After treatment with functional appliances, the condyle was found to be in a more advanced position, with remodelling of the condyle and adaptation of the morphology of the glenoid fossa. No significant adverse effects on the TMJ were observed in healthy patients and the appliances could improve joints that initially presented forward dislocation of the disk.

Key words:Temporomandibular joint, TMJ, orthodontic appliances, functional, mandibular advancement, herbst appliance, bionator.

Evaluation of the effects of skeletal anchoraged Forsus FRD using miniplates inserted on mandibular symphysis: A new approach for the treatment of Class II malocclusion

OBJECTIVE

To evaluate the skeletal, dentoalveolar, and soft tissue effects of the Forsus Fatigue Resistant Device (FRD) appliance with miniplate anchorage for the treatment of skeletal Class II malocclusion.

MATERIAL AND METHODS

The prospective clinical study group included 17 patients (11 girls and 6 boys; mean age 12.96 ± 1.23 years) with Class II malocclusion due to mandibular retrusion and treated with skeletal anchoraged Forsus FRD. After 0.019 × 0.025-inch stainless steel archwire was inserted and cinched back in the maxillary arch, two miniplates were placed bilaterally on the mandibular symphysis. Then, the Forsus FRD EZ2 appliance was adjusted to the miniplates without leveling the mandibular arch. The changes in the leveling and skeletal anchoraged Forsus FRD phases were evaluated by means of the Paired and Student's t-tests using the cephalometric lateral films.

RESULTS

The success rate of the miniplates was found to be 91.5% (38 of 42 miniplates). The mandible significantly moved forward (P < .001) and caused a significant restraint in the sagittal position of the maxilla (P < .001). The overjet correction (-5.11 mm) was found to be mainly by skeletal changes (A-VRL, -1.16 mm and Pog-VRL, 2.62 mm; approximately 74%); the remaining changes were due to the dentoalveolar contributions. The maxillary and mandibular incisors were significantly retruded (P < .001).

CONCLUSION

This new approach was an effective method for treating skeletal Class II malocclusion due to the mandibular retrusion via a combination of skeletal and dentoalveolar changes.

Use of Forsus fatigue-resistant device in a patient with Class I malocclusion and mandibular incisor agenesis

Orthodontic treatment in patients with congenitally missing teeth can be challenging. In this case report, we describe the treatment of a 15-year-old girl with mild dental crowding and 2 congenitally missing mandibular incisors. The Forsus fatigue-resistant device was used to move the mandible and the mandibular teeth forward. A new balanced and stable occlusion was achieved after treatment. When the treatment plan includes moving the mandibular teeth forward in a patient with mandibular incisor agenesis, the profile and the skeletal and dental features should be carefully scrutinized to ensure that balanced and esthetic results are achieved.

Condylar response to functional therapy with Twin-Block as shown by cone-beam computed tomography

OBJECTIVE

To evaluate the condylar changes through cone-beam computed tomography (CBCT) images in patients treated with Twin-Block functional appliance.

MATERIALS AND METHODS

In this retrospective study, CBCT images of 30 patients who were treated with the Twin-Block appliance were used. Mandible was segmented and pretreatment and posttreatment (T0 and T1) condylar volume was compared. The angle between sella-nasion-Point A (SNA), angle between sella-nasion-Point B (SNB), angle between Point A-nasion-Point B (ANB), midfacial length (Co-A), mandibular length (Co-Gn), and the distances from right condylion to left condylion (CoR-CoL) were also measured on three-dimensional images. Differences were analyzed with Wilcoxon signed rank tests, and Mann-Whitney U-tests were used to compare the scores of male and female participants. Significance was set at P < .05.

RESULTS

In this study, a decrease in SNA and ANB (P < .05 and P < .01, respectively) and an increase in SNB (P < .01) were found. Additionally, CoR-CoL, Co-Gn, and condylar volume increased at both the left and right sides (P < .01). However, increase at Co-A was not statistically significant (P > .05). Comparison of differences by sex was not statistically significant for all measurements (P > .05).

CONCLUSION

Twin-Block appliance increases condylar volume, mandibular length, and intercondylar distance by stimulating growth of condyle in an upward and backward direction.

Clinical effect of Tip-Edge plus appliance in children with angle II(1) malocclusion

The effects of Tip-Edge plus appliance in the treatment of Angle II(1) malocclusion and the mechanism were investigated. Fifty-two Angle II(1) children, aged from 12.3-14.2 years, with mandibular retrusion in permanent dentition were selected and treated with Tip-Edge plus appliance. Lateral cephalometric films taken before and after treatment were analyzed. The arithmetic mean and standard deviation were calculated for each variable. Paired t-test was performed to evaluate the significant treatment change. Results showed that the average treatment time was 16 months. Normal overjet and overbite were established with retroclination of upper incisors and proclination of lower incisors. U1-NA was decreased by 15.4° (P<0.01). ANB and Y axial angle were decreased significantly (P<0.05). Soft tissue measurements showed that FCA and UL-E were decreased dramatically (P<0.05), and LL-E was increased significantly (P<0.05). Remarkable soft tissue change was noted after the treatment and convex facial profile changed to the straight profile. In conclusion, Tip-Edge plus technique can quickly and efficiently correct anterior bite and lateral outlook.

Analysis of Criteria for MRI Diagnosis of TMJ Disc Displacement and Arthralgia

Aims. To improve diagnostic criteria for TMJ disc displacement (DD). Methods. The standard protocol for MRI diagnosis of DD, using a 12 o'clock reference position, was compared to an alternative protocol. The alternative protocol involves the functional relationship between the condyle and articular eminence, using a line perpendicular to the posterior slope of the eminence as a reference for disc position. The disc location was examined using both protocols, and disc diagnoses were compared in their relationship with joint pain. Statistical analyses included P value, sensitivity, specificity, odds ratio, and kappa statistic. Results. 58 MRIs were interpreted. 36 subjects reported arthralgia; 22 did not. Both protocols demonstrated significance (standard P = 0.004, alternative P < 0.001) for the ability to predict arthralgia. The odds of arthralgia increased in DD patients diagnosed by standard methods 9.71 times and in DD diagnosed by alternative means 37.15 times. The diagnostic sensitivity decreased 30% using the alternative versus the standard protocol (0.6389 versus 0.9444), while specificity increased 60% (0.9545 versus 0.3636). Conclusions. A stronger relationship occurs between DD and arthralgia when using a function-based protocol. The alternative protocol correctly identifies subjects without arthralgia, who by standard methods would be diagnosed with DD, as having nondisplaced discs, providing a more clinically relevant assessment of TMJ disc displacement.

Imaginologia da articulação temporomandibular durante o tratamento ortodôntico: uma revisão sistemática

INTRODUÇÃO: a evolução da Imaginologia na Odontologia propiciou uma série de vantagens para o diagnóstico e elaboração de planos de tratamento em diversas especialidades. Exames como ressonância magnética nuclear, tomografia computadorizada e tomografia volumétrica Cone Beam, bem como métodos de reconstrução em 3D, permitiram analisar de forma precisa estruturas orofaciais.Aliado a esse fato,com a realização de estudos clínicos com metodologias e desenhos adequados, pode-se avaliar os efeitos do tratamento ortodôntico sobre a articulação temporomandibular (ATM). OBJETIVO: esse trabalho, através de uma revisão sistemática de literatura, teve como objetivo analisar a inter-relação entre o tratamento ortodôntico e a ATM, verificando se a Ortodontia acarreta alguma alteração das estruturas internas da ATM. MÉTODOS: levantamento em bases de pesquisa (MEDLINE, Cochrane, EMBASE, Pubmed, Lilacs e BBO), entre os anos de 1966 e 2009, com enfoque em estudos clínicos randomizados, estudos longitudinais prospectivos não randomizados, revisões sistemáticas e meta-análises. RESULTADOS: após a aplicação dos critérios de inclusão, chegou-se a 14 artigos, sendo que 2 eram estudos clínicos randomizados e 12 eram estudos longitudinais sem critérios de randomização. CONCLUSÕES: pela análise da literatura, conclui-se que a realização do tratamento ortodôntico não ocorre à custa de posicionamentos não fisiológicos do côndilo e disco articular. Algumas mecânicas podem acarretar remodelações dos componentes ósseos articulares.

Changes in temporomandibular joint disc position and form following Herbst and fixed orthodontic treatment

OBJECTIVE

To determine the changes in the position and form of the temporomandibular joint articular disc in adolescents with Class II division 1 malocclusion and mandibular retrognathism treated with the Herbst appliance (phase I) and fixed orthodontic appliance (phase II).

MATERIALS AND METHODS

Thirty-two consecutive adolescents went through phase I of treatment and 23 completed phase II. The temporomandibular joints were evaluated qualitatively by means of magnetic resonance images at the beginning of treatment (T1), during phase I (T2), at the end of phase I (T3), and at the end of phase II (T4).

RESULTS

Significant changes in disc position were not observed with the mouth closed between T1 x T3 (P = .317), T3 x T4 (P = .287), or T1 x T4 (P = .261). At T2, on average, the disc was positioned regressively. With the mouth open, no difference was observed between T1 x T3 (P = .223) or T1 x T4 (P = .082). We did observe a significant difference between T3 x T4 (P < .05). Significant changes in the disc form were found with the mouth closed between T1 x T2 (P < .001) and T2 x T3 (P < .001).

CONCLUSIONS

At the end of the two-phase treatment, in general terms, the position and form of the initial articular discs were maintained; however, in some temporomandibular joints some seemingly adverse effects were observed at T4.