Repeated Botulinum Toxin Type A Injections on Intramuscular Fat Accumulation in Individuals With Sleep Bruxism.

Inclusion Criteria: * Adults aged 18 years or older. * Clinical diagnosis of probable sleep bruxism according to the international consensus criteria proposed by Lobbezoo et al. * Indication for BoNT-A injection in the masseter muscle due to bruxism-related pain or muscle hypertrophy. * Willingness to undergo repeated BoNT-A injections at six-month intervals. * Willingness to participate in ultrasonographic evaluations at each follow-up visit. Exclusion Criteria: * Presence of neurological or neuromuscular disorders affecting the masticatory muscles (e.g., dystonia, myasthenia gravis). * History of orofacial trauma, temporomandibular joint dysfunction, or maxillofacial surgery. * Systemic diseases that may affect neuromuscular transmission or muscle metabolism. * Use of medications known to interfere with neuromuscular function, including aminoglycoside antibiotics or corticosteroids.