[Quantitative analysis based on three-dimensional stereophotogrammetry in the observation of curative effect of botulinum toxin A on masseter hypertrophy].

[OBJECTIVE] To observe the curative effect of botulinum toxin A on masseter hypertrophy using three-dimensional stereophotogrammetry.

[METHODS] 46 cases with masseter hypertrophy (92 masseters) who received botulinum toxin A injection were enrolled from May 2013 to August 2014.Data were collected before and 3,6 and 9 months after injection.

[RESULTS] The efficacy of botulinum toxin A in reducing the volume of the lower face has been proven by MAS 3D.3 and 6 months after injection, the volume reduction were measured as 7.23 ％,2.15％ respectively (P ＜ 0.05).The coefficients between middle and lower thirds of the face showed an increase compatible with thinning of the lower face with statistical significance at 3 months follow up. The increase percentage was measured by MAS 3D as 40.21％ between pre-and post-injection (P ＜ 0.05),and the increase percentage was 21.03％ at 6 months follow up (P ＜ 0.05).While 9 months after injection,the value was insignificant comparing to pretreatment at 9 months.

[CONCLUSIONS] Three-dimensional stereophotogrammetry provides a safe effective and direct way to observe masseter hypertrophy.