This study investigated whether the shape of the face affects how jaw muscles respond to botulinum toxin injections in people who grind their teeth (bruxism). Participants were divided into two groups based on their facial structure: low-angle (shorter face height) and normal-angle. Each participant received botulinum toxin type A injections into the masseter (jaw) muscle. Bite force measurements were taken before and 15 days after the injection using the T-Scan computerized occlusal analysis system. The study aimed to determine whether facial structure influences the early changes in bite force balance following the injection.