Is Mandibular Cortical Bone and Trabecular Microarchitecture Altered by Masseter Botox Treatment? A Quantitative Perspective

Background/Objectives: Bruxism is a prevalent parafunctional activity that induces masticatory muscle hypertrophy and physiological mandibular bone alterations. While botulinum toxin type A (BTX-A) injections effectively reduce muscle hyperactivity, objective radiological assessment of their skeletal effects remains limited. This study aimed to quantitatively evaluate the impact of BTX-A on mandibular trabecular bone structure by assessing potential reductions in fractal dimension (FD) in bruxism patients compared to controls. Methods: This retrospective matched-pair study included 42 bruxism patients (39 females, 3 males) receiving 50 U of BTX-A in masseter muscles and 32 age-matched non-bruxism controls (30 females, 2 males). Pre- and 6-month post-treatment panoramic radiographs were analyzed. FD values were calculated from bilateral condylar neck, ramus, and angulus regions. Results: Statistically significant reductions in FD values were observed in the angulus regions post-treatment (Right: 1.3856 to 1.2995; Left: 1.3718 to 1.2529, p < 0.001). Postoperative FD values in the BTX-A group showed no significant differences when compared to the control group (p > 0.05). Conclusions: BTX-A administration leads to measurable, region-specific reductions in mandibular trabecular bone fractal dimension, particularly in the angulus. The postoperative similarity to the control group suggests a potential normalization of bone structure following treatment. These findings highlight the clinical utility of fractal analysis for monitoring osseous adaptations in neuromuscular interventions.