The influence of different skeletal patterns on TMJ anatomy: a comprehensive CBCT study across various sagittal and...

This study aimed to evaluate the impact of sagittal and vertical skeletal patterns as well as gender on temporomandibular joint (TMJ) morphology using Cone Beam Computed Tomography (CBCT).

A cross-sectional analysis was conducted on CBCT scans of 126 adult patients (63 females, 63 males) aged 20 to 40 years, stratified into Class I, II and III sagittal classifications and further divided by vertical patterns: horizontal, normal and vertical. Measurements included condylar dimensions (length, height, and width) and glenoid fossa dimensions (depth and width). Left and right TMJs were assessed and average values were used due to the absence of significant side differences. A multiple linear regression model was used to examine the effects of sagittal and vertical patterns and Gender on the parameter. Gender was included as a covariate in all models. Both an interaction model (vertical × sagittal pattern) and a main-effects-only model were considered with interaction effects accounted for where present. Model selection was based on statistical significance and model fit criteria. Pairwise comparisons were conducted using Tukey's Honest Significant Difference (HSD) test and estimated marginal means (EMMs) were calculated where applicable. Statistical significance was set at p < 0.05 with adjustments for multiple comparisons.

For Condyle Height, a significant difference was found between Class III and Class I within the vertical pattern (VP) subgroup (p = 0.011). In contrast, Gender significantly influenced Condyle Length (p = 0.009) and a significant difference was found between Class II and Class I (p = 0.01). Subgroup analysis revealed a significant difference between Class II and Class I in the VP group (p = 0.023). For Condyle Width, a significant interaction between VP and Class III was found (p = 0.029). Significant pairwise differences were observed between HP-Class II and VP-Class III (p = 0.023), NP-Class II and VP-Class III (p = 0.007), and HP-Class III and VP-Class III (p = 0.013). Within the NP subgroup, Class II differed significantly from Class I (p = 0.044). Analysis of Glenoid Fossa Width revealed a significant interaction between NP and Class III (p = 0.048). Multiple significant pairwise differences were identified, including NP-Class I versus HP-Class II (p = 0.002), NP-Class I versus NP-Class II (p = 0.004), and VP-Class II versus HP-Class III (p = 0.004). Regarding glenoid fossa depth, a significant interaction between VP and Class III was found (p = 0.037), but no pairwise subgroup differences reached statistical significance (all p > 0.05).

This study demonstrates that TMJ morphology is variably influenced by vertical and sagittal skeletal patterns and gender. Significant differences in condyle length and width as well as glenoid fossa width were primarily observed in individuals with vertical patterns and Class II or III skeletal relationships. Gender significantly affected condyle length. While glenoid fossa depth showed a high interaction between vertical pattern and sagittal skeletal relationships, no individual comparisons reached statistical significance. These findings underscore the nuanced interplay of sagittal and vertical skeletal patterns in shaping TMJ morphology.