Abstract
BACKGROUND: Masseter muscle prominence (MMP) contributes to a widened lower facial shape, considered aesthetically undesirable to some individuals. This study assessed lower facial shaping improvements with onabotulinumtoxinA. METHODS: In a phase 2, randomized, placebo-controlled study, onabotulinumtoxinA (24, 48, 72, or 96 U) or placebo was injected intramuscularly (3 sites per masseter) into subjects with bilaterally symmetric "marked" or "very marked" MMP on the Masseter Muscle Prominence Scale (MMPS). Changes from baseline at day 90 in lower facial width, mandibular facial angle, investigator-rated MMPS response, subject-perceived symptoms, psychosocial impact of lower face appearance, and satisfaction with lower face on the Lower Facial Shape Questionnaire were assessed. RESULTS: Among 187 subjects (mean age, 35.4 years; 81.8% female; and 79.7% Asian), significant reductions from baseline in lower facial width and mandibular angle were achieved with all onabotulinumtoxinA doses versus placebo at day 90 ( P < 0.001, each parameter), continuing through day 180. At day 90, greater improvements in MMPS grade (all doses) and MMP signs, psychosocial impacts, and satisfaction were observed. CONCLUSION: OnabotulinumtoxinA treatment improved lower facial shape in individuals with MMP, producing a more desirable ovoid appearance for at least 6 months, with greater patient satisfaction.