Masseter Muscle Thickness and Mandibular Trabecular Complexity: A Cross-Sectional Study.

Background: To evaluate the association between masseter muscle thickness and mandibular trabecular complexity in subjects with and without myogenous temporomandibular disorders (TMDs). Materials and Methods: A cross-sectional study was conducted including 77 participants (41 controls and 36 with TMD). Masseter muscle thickness was measured using ultrasonography, and fractal analysis was performed on panoramic radiographs. Associations were assessed using Spearman correlation and linear regression models. Multivariable analyses were adjusted for age, sex, and diagnostic group. Results: A weak positive correlation was observed between masseter thickness and fractal dimension ( = 0.255, p = 0.025). In unadjusted regression, masseter thickness was significantly associated with fractal values (p = 0.019). However, this association was attenuated and no longer statistically significant after adjustment for age, sex, and diagnostic group (p = 0.091). Sex was significantly associated with masseter thickness (p < 0.001) but not with fractal dimension. In contrast, TMD was independently associated with higher fractal dimension values (p = 0.011). No significant interaction between masseter thickness and diagnostic group was observed. Conclusions: Masseter muscle thickness shows a weak association with mandibular trabecular complexity that varies according to demographic factors. In contrast, TMD is independently associated with higher fractal dimension values, suggesting that mandibular bone microarchitecture is associated with complex functional and clinical influences beyond muscle morphology alone.