Three-Dimensional Evaluation of Mandibular Asymmetry in Adult Violin and Viola Players: A Prospective Cone-Beam Computed Tomography Study

Long-term violin and viola performances involve sustained asymmetric loading of the craniofacial skeleton; however, their association with 3-dimensional mandibular asymmetry has not been well characterized. This prospective study aimed to evaluate mandibular asymmetry using cone-beam computed tomography (CBCT) in adult violin and viola players who have undergone prolonged intensive musical training since childhood. We prospectively included 20 adult violin and viola players, enrolled in or who graduated from the College of Music, Seoul National University. Participants underwent standardized questionnaire-based assessments, including playing history, practice characteristics, and playing-related musculoskeletal symptoms. Three-dimensional CBCT images were reconstructed following standardized reorientation. Bilateral mandibular morphology was evaluated using linear measurements (condylion-gonion, mandibular notch-gonion, and gonion-menton distances), hemimandibular volume, and asymmetry indices (AI). Associations between mandibular asymmetry and questionnaire-derived playing-related variables were analyzed using univariate regression analyses. Handspan measurements were collected as secondary outcome measures to evaluate skeletal laterality associated with prolonged unilateral hand training, providing an additional indicator of musculoskeletal adaptation beyond the craniofacial skeleton. Three-dimensional CBCT demonstrated right-sided predominance in the condylion-gonion distance, mandibular notch-gonion distance, and hemimandibular volume. The gonion-menton distance showed a small, nonsignificant, left-sided predominance. All hand measurements showed a left-sided predominance. No playing-history variable was significantly associated with directional side differences. Adult violin and viola players exhibited characteristic 3-dimensional mandibular asymmetry, with a right-sided predominance of the ramus and hemimandibular volume, accompanied by left-sided hand-span dominance. These findings suggest that prolonged asymmetric mechanical loading during intensive musical training may contribute to adaptive skeletal laterality.