Sermswan P, Tansatit T, Meevassana J, Panchaprateep R. A Cadaveric Study of Dye Spreading: Determining the Ideal Injection Pattern for Masseter Hypertrophy.
Dermatol Surg 2021;
47:1354-1358. [PMID:
34417381 DOI:
10.1097/dss.0000000000003171]
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Abstract
BACKGROUND
Masseter hypertrophy is the main cause of an asymmetrical and squared lower facial contour in the Asian community. Botulinum toxin injection technique is crucial to treat this condition.
OBJECTIVE
To improve injection techniques for masseter hypertrophy by elucidating the distribution of the injections within the masseter.
METHODS
Thirty masseter muscles were divided into 6 groups of 5 muscles each. Each group received one 0.2- or 0.3-mL injection at Point A, B, or C according to a three-point technique. Muscle dimensions and dye of the primary and secondary dye spreading were measured.
RESULTS
The average muscle length, width, and thickness were 69.87, 33.50, and 11.23 mm, respectively. The average primary longitudinal and horizontal spreading was 36.56 and 15.60 mm, respectively. No statistically significant difference was found between 0.2- and 0.3-mL injections at each point.
CONCLUSION
The three-point technique best fits in the safe zone and should be the standard injection technique for masseter hypertrophy. Injection at Points B and C may create secondary spreading that affect the risorius muscle and the parotid gland which are the cause of asymmetrical smiling and xerostomia, respectively. The dosage should be adjusted according to the muscle volume and not only the thickness.
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