Abstract
We report a case of bilateral hypertrophy of the masseter muscle, judging from the axial CT. A 14-year-old girl was referred to our clinic complaining of bilateral protrusion around the angular region of the mandible. There was, however, no morphological abnormality in the mandible. Axial CTs revealed that the widest portion of the masseter muscle was 18mm and this volume of the muscle was statistically wider than that of other females of approximately the same age. Under general anesthesia, the bilateral deeper layers of the masseter muscle were intra-orally resected. Training in mouth opening was started at 5 days after the operation, and she achieved an adequate opening range of motion. On axial CTs at one year after her surgery, the volume of the masseter muscle was reduced to 61% compared with the original volume. She was satisfied with the result of the operation, cosmetically and functionally.
