Temporomandibular joint articular disc position and shape in skeletal Class III

Objective To compare the position and shape of the temporomandibular joint (TMJ) articular disc among the sagittal and vertical skeletal patterns in Angle Class III, Class III subdivision malocclusion and normal occlusion. The null hypothesis was that there was no difference in disc position and shape in different (1) malocclusions and (2) skeletal patterns. Methods This cross-sectional observational study evaluated 105 patients divided into 3 groups: Class III (33, 9.39 +/- 1.96 years), Class III subdivision (45, 9.51 +/- 1.59 years) and a normal occlusion (27, 10.24 +/- 0.87 years) was included as healthy control. Severity of the maxilla-mandibular anteroposterior discrepancy and vertical facial pattern were determined using 2D cephalometry, and the position and shape of the articular discs were evaluated in magnetic resonance images. Statistical parametric and non-parametric tests and Kappa analysis for intra-observer and inter-observer assessment were used (p <= .05). Results Significant between-group differences were found in articular disc position. In the normal occlusion group, all the articular discs were well positioned. In Class III and Class III subdivision, the discs were displaced in 30.3% and 12.2% of the TMJs, respectively. Sagittal and vertical skeletal patterns did not affect the findings significantly. The Class III subdivision malocclusion group is probably different from the other groups, showing 97.7% of biconcave discs in both TMJs. Conclusion The longitudinal follow-up of this sample becomes relevant as the two groups with malocclusion in the pre-peak phase of pubertal growth showed differences in the prevalence of displacement and form of the articular disc, with no association with their vertical facial characteristics.

Automated summary

This study compared the position and shape of the temporomandibular joint articular disc in different malocclusions and skeletal patterns. The results showed significant differences in disc position among different groups, and the Class III subdivision group was found to have a higher prevalence of biconcave discs.