Effect of Rapid Maxillary Expansion on Glenoid Fossa and Condyle-Fossa Relationship in Growing Patients (MEGP): Study Protocol for a Controlled Clinical Trial

Evaluation of condylar dimension and position following rapid maxillary expansion with tooth- or tooth-bone-borne appliances

Objective

To assess and compare changes in the dimension and position of the mandibular condyle after tooth-borne (Hyrax) and tooth-bone-borne (Hybrid Hyrax) expansion.

Methods

Twenty-five patients who underwent expansion with either tooth-borne appliances (8 girls, 5 boys; mean age 14.3 ± 2.3 years) or tooth-bone-borne appliances (6 girls, 6 boys; mean age 13.8 ± 2.2 years) were examined. Condylar and glenoid fossa morphology before (T0) and 3 months after (T1) expansion were evaluated using cone-beam computed tomography. Condylar measurements (anterior, posterior, and superior joint spaces; condylar height, length, and width), along with sagittal and vertical skeletal and maxillary transversal measurements, were analyzed using Dolphin Imaging software. Wilcoxon and Paired t tests were used for T0 and T1 evaluations, and the Mann-Whitney U test for intergroup comparisons.

Results

At both T0 and T1, no statistically significant differences were observed between the groups in terms of condylar dimensions or the position of the condyle within the glenoid fossa. Maxillary transversal measurements increased after expansion in both groups (P < 0.01), with a significantly greater increase in first premolar width in the Hyrax group (P < 0.05). The vertical position of the posterior teeth showed no noteworthy changes (P > 0.05), except for the right second premolar. Temporomandibular joint measurements did not significantly change in either group after treatment (P > 0.05).

Conclusions

Neither tooth-borne nor tooth-bone-borne expansion caused significant changes in the condylar dimensions and position at the end of treatment.

The Short-Term Effect of Active Skeletonized Sutural Distractor Appliance on Temporomandibular Joint Morphology of Class III Malocclusion Subjects

Objectives  The purpose of this study was to evaluate the short-term effect of active skeletonized sutural distractor (ASSD) appliance on temporomandibular joint morphology of class III malocclusion subjects.

Materials and Methods  This was a prospective interventional study. Cone-beam computerized tomography (CBCT) images of 22 patients were taken before and after treatment by using Planmeca Promax 3D CBCT machine version 2.9.2 (Planmeca OY Helsinki, Finland). The condylar width, height, length, roof of glenoid fossa thickness, and all joint spaces were measured. The condylar position was determined based on Pullinger and Hollander formula. The condylar shape was determined as per Kinzinger et al. The condylar volume was calculated by using Mimics software (Materialize, Belgium).

Statistical Analysis  Data analysis was performed by using SPSS software version 24. Wilcoxon paired signed-rank test was used to compare the difference in temporomandibular joint morphology and condylar volume between pre- and post-treatment measurements. Chi-square test was used to compare the condylar position and shape.

Results  The superior ( p = 0.000 on the right side, p = 0.005 on the left side) and posterior joint spaces ( p = 0.000 on both sides) were decreased after the treatment, respectively. The condyles were rotated upward and backward, thereby increasing the anterior joint spaces ( p = 0.000 on both sides) after the treatment. The condylar volume increases after treatment, but no significant differences were observed ( p = 0.903 on the right side, p = 0.062 on the left side).

Conclusion  The significant changes were observed in joint spaces. The condyles were more anteriorly placed before treatment. Condylar position and shape alter in response to ASSD treatment. The condylar volume did not show any significant change.

Effects of rapid maxillary expansion on temporomandibular joints

OBJECTIVE

To evaluate the impact of rapid maxillary expansion (RME) on the condylar position, disc joint, joint space, and interarticular relationship in growing patients.

MATERIALS AND METHODS

A systematic search was performed in nine databases. The clinical studies selected included those with pre- and post-magnetic resonance, conventional computed tomography or cone beam tomography in growing patients. Risk of bias assessment was performed using the Cochrane Collaboration tool for controlled clinical studies and National Heart, Lung, and Blood Institute (NHLBI) Quality Assessment for Before-After Studies With No Control Group.

RESULTS

Initially, 4303 records were identified. Only eight studies fulfilled the criteria and were included in the qualitative analysis. Of those, two were controlled clinical studies with a risk of uncertain to high bias. The remaining papers had a low to moderate risk of bias. Results showed that RME in children and adolescents promoted the following: remodeling in the head and or condylar branch, changes in condylar position and joint space, maintenance of improved symmetry between the condyles, and no ability to modify the position or shape of the articular disc.

CONCLUSIONS

RME in growing patients is able, in the short term, to modify the condyle-fossa relationship but does not change the position or shape of the articular disc. The intercondylar symmetric relationship is maintained or improved. Although the NHLBI score shows low to moderate risk of bias, the clinical relevance of these review findings is limited by Cochrane and Grades of Recommendation, Assessment, Development and Evaluation scores.