Central and Peripheral Sensitization in Temporomandibular Disorders: Proposed Mechanisms of Botulinum Toxin Therapy

Temporomandibular disorders (TMDs) are common musculoskeletal chronic orofacial pain conditions involving peripheral and central sensitization within trigeminal nociceptive pathways, manifesting as mechanical allodynia and functional impairment. Botulinum toxin type A (BoNT-A) has been explored as a treatment targeting both muscle hyperactivity and nociceptive modulation. Preclinical and clinical evidence demonstrate that BoNT-A reduces peripheral neurotransmitter release, neurogenic inflammation, and central neuronal excitability, leading to attenuation of mechanical allodynia in TMD models and patients. Clinical trials show modest and variable analgesic effects, with patients displaying sensory sensitization appearing to respond more favorably, though methodological heterogeneity limits definitive conclusions. Safety concerns related to muscle weakening, changes in bone density, and structural changes underscore the need for standardized protocols optimizing dosing and monitoring, in addition to prospective studies. These findings suggest that BoNT-A may serve as an adjunctive, mechanism-based therapy within multimodal TMD management. Future research should focus on standardized sensory phenotyping and trial design to clarify BoNT-A's role in modulating central sensitization and improving patient outcomes.