The Comparison of Long-term Effect of Botox(R) Injection on Lower Face Contouring after Single Injection and Long-term Repeated Injections by Standardized Photograph Analysis

ABSTRACT

PURPOSE: A botulinum toxin type A(BoNT-A) injection has been used as a noninvasive management for lower face contouring since 2000. The aim of this study is to compare reduction rate of lower face width for a longtime according to repeated Botox(R) injections on masseter muscles for lower face contouring procedure. METHODS: Forty-five patients were analyzed for single session of Botox(R) injection and 13 patients were evaluated for repeated Botox(R) injections for over two years. Single injection group was tracked regular intervals at 1, 3, 6, 10, 12 months after the injection, and repeated injection group was measured at every injection time. Twenty-five to thirty units of Botox(R) was injected into each masseteric muscle at five to six points at the prominent portions of the mandibular angle. Standardized frontal view of digital photographs were analyzed by Adobe Photoshop(R)(version CS3) to measure an reduction rate of lower face's width. RESULTS: Reduction rate was 3.7%, 6.9%, 6.2%, 4%, 4% at 1, 3, 6, 10, 12 months post injection each other in single injection group. However, more than 8% reduction rate was found in repeated injection group persistently for more than two years. CONCLUSION: This study shows that effective duration of Botox(R) injection for lower face contouring is expected to continue over one year clinically. Moreover, repeated injections maintained lower reduction rate consistently for a long time. Therefore, repeated injections on masseter muscles at regular intervals is the most effective procedure for lower face contouring.