Botulinum Toxin Injection Technique for Reducing the Masseter Size and Enhancing the Jawline.

[BACKGROUND] The injection of botulinum toxin into the masseter muscle is an important method for improving hypertrophy. However, some patients may experience adverse reactions, such as sagging of the lower jaw. Therefore, we proposed a method of injecting botulinum toxin into the masseter and platysma muscles that would reduce masseter size and enhance the jawline.

[OBJECTIVES] The aim of this study was to reduce the masseter size while enhancing the jawline.

[METHODS] Twenty patients received botulinum toxin injections into the masseter and platysma muscles. Pain levels were evaluated with the visual analog scale. All patients were photographed before and 6 months after treatment. Evaluations were performed based on standardized criteria. The lift index, reduction index, and symmetry index were performed to assess the degree of jawline elevation, masseter size reduction, and jawline symmetry before and after treatment.

[RESULTS] The mean visual analog scale score of the 20 patients was 2.80 (±1.24). The mean lift index score decreased from 4.93 (±0.34) to 4.53 (±0.37), P < .05. The mean reduction index score decreased from 3.13 (±0.27) to 2.74 (±0.27), P < .05. The mean symmetry index score changed from 0.0393 (±0.0296) to 0.0257 (±0.0246), P < .05.

[CONCLUSIONS] Botulinum toxin injections into the masseter and platysma muscles through nerve block reduced the masseter size, elevated the jawline, and improved symmetry.