2D–3D comparison of the temporomandibular joint in skeletal Class II versus Class I adults: A retrospective study

Objective: To compare the temporomandibular joint (TMJ) morphological characteristics in people with Class II versus Class I sagittal skeletal relationship and to identify other factors that influence the TMJ dimensions. Material and methods: This cross-sectional and retrospective study evaluated 188 people divided into two groups, 92 cone-beam computed tomographies (CBCTs) and lateral radiographs (LR) of people with Skeletal class II relationship with Class II division 1 malocclusion versus 96 CBCTs and LR of people with Class I skeletal relationship and Class I malocclusion (controls). The CBCTs included people of both sexes, aged between 15 and 65 years old. The 3D Imaging Carestream Software was used to evaluate the condyle height and neck width, mediolateral and anteroposterior condyle dimensions, the shape of the glenoid fossa and condyle in the CBCTs. Likewise, the ANB angle, the Wits appraisal and other measurements were evaluated on LR. Besides, Mann-Whitney U, Chi² and multiple linear regression tests were performed. The significance level was set at P ˂ 0.05. Results: The mediolateral and anteroposterior condyle dimensions were smaller in class II people (1.82 mm and 0.29 mm, respectively) than class I people (P < 0.05). Likewise, height and neck width of condyle were smaller in class II people (0.73 mm and 0.40 mm, respectively) than class I people (P < 0.05). Multiple linear regression identified mainly the ANB angle as a factor (P < 0.05) that influenced the dimensions, decreasing the condyle dimensions in skeletal class II relationship. Conclusions: People with skeletal class II relationship showed smaller condyle dimension values than class I people. A decrease in the dimensions of the eminence and the condyle could be expected when the ANB angle increases.