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Updated: Jun 7, 2025
Rodent Model of Masseter Volumetric Muscle Loss for Studying Bioengineering Materials
Published on: May 31, 2024
Reduction of masseter muscle prominence after treatment with onabotulinumtoxinA: Primary results from a randomized
Jean Carruthers1, Steven Liew2, Jason K Rivers3
1Dr Jean Carruthers Cosmetic Surgery Inc., Vancouver, British Columbia, Canada.
Background:
OnabotA is used to treat masseter muscle prominence (MMP).
Objective:
To assess the safety and efficacy of OnabotA for MMP in a randomized study.
Methods:
This 12-month, multicenter, double-blind, placebo-controlled, phase 2 study randomized adults (18-50 years of age) with marked/very marked bilateral MMP (≥4 on the Masseter Muscle Prominence Scale [MMPS]) to OnabotA (24, 48, 72, or 96 U) or placebo; retreatment occurred at day 180 if MMPS ≥4. Lower facial volume at day 90 was measured using Vectra 3-dimensional photography. Safety assessments included computed tomography and dental exams. Evaluations occurred monthly through day 360.
Results:
Among 187 randomized subjects, significant lower facial volume reductions and percentage of responders (MMPS grade ≤3) were greater with OnabotA versus placebo at day 90 (P < .001 and ≤.008, respectively). Similar efficacy was observed with retreatment. No dose-related safety trends or clinically relevant changes in the mandible or teeth occurred. Localized impact on smile was reported with 96 U OnabotA (n = 4).
Limitations:
Limited sample size per individual treatment group.
Conclusion:
OnabotA administered in 1 or 2 treatments over 1 year was associated with significant reductions in masseter muscle volume and MMP severity, with an acceptable safety profile.
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