Efficacy and Safety of a Novel Botulinum Toxin A for Masseter Reduction: A Randomized, Double-Blind, Placebo-Controlled, Optimal Dose-Finding Study

Abstract

BACKGROUND A wide lower face and a square jaw are considered esthetic problems, particularly in Asia. OBJECTIVE To investigate the optimal dose of a novel botulinum toxin (prabotulinum toxin A) for treating masseteric hypertrophy. METHODS Ninety subjects with masseteric hypertrophy were randomly divided into 5 groups and treated with placebo (A, normal saline) or prabotulinum toxin A (B: 24, C: 48, D: 72, and E: 96 units). Photography, ultrasonography, and 3-dimensional imaging were performed before and after injection at baseline and at 4, 8, 12, and 16 weeks after treatment. The participants also rated their satisfaction. RESULTS Masseter thickness significantly reduced in all groups at 12 weeks, compared with that in the placebo group. A dose-dependent reduction in masseter thickness was observed at the resting and maximal clenching positions. Sonography and 3-dimensional imaging revealed a gradual reduction in masseter thickness and volume, respectively, during the first 12 weeks. Despite being slightly effective, a dose of 24 units might be insufficient for resolving square face problems. Patients in Group E reported discomfort during jaw movement. CONCLUSION Prabotulinum toxin A could effectively improve lower face contour without major complications, with an optimal dose of 48 to 72 units, followed by reinjection after 12 weeks.

Three-dimensional soft tissue landmark detection with marching cube algorithm

“…This area did not protrude from the center of the cheek, nor was it in the middle of the cheek area; neither point was clinically meaningful. Hence, before-and-after evaluations of cheek area modifications such as MEDPOR augmentation 37 , soft tissue treatments with botulinum toxins 38 – 40 , malar-plastic surgery 41 , and changes in soft tissue when treated by mini-screw-assisted rapid palatal expanders 36 could not be precisely assessed using these landmarks. However, in this study, when using the marching cube algorithm to digitize dots on the cheeks (Ch_r, Ch_l) using Program S, the most protruding area could be evaluated, which is clinically significant, and can possibly be applied to the evaluation of the forementioned treatments.…”

Botox Therapy for Hypertrophy of the Masseter Muscle Causes a Compensatory Increase of Stiffness of Other Muscles of Masticatory Apparatus

“…In a randomized controlled study conducted by Hong et al (2021), the effective dose range for a reduction of the masseter muscle ranged from 48 to 72 units. They also found that gradual reduction was observed up until 12 weeks and after that period, reinjection should be considered for maintaining satisfactory cosmetic effect [ 30 ].…”

“…It also helps to evaluate the condition of the masseter muscle and surrounding tissues, thus, differential diagnosis. Ultrasound measures muscle thickness which is helpful for the determination of the optimal dose of Botox [ 26 , 30 , 31 , 32 , 33 ]. Magnetic resonance and computerized tomography of the masseter regions are performed commonly for the purpose of differential diagnosis with some attempts to use them for assessments of treatment effects [ 34 ].…”

Efficacy of botulinum toxin in masseter muscle hypertrophy for lower face contouring

“…Frequent BTA or Xeomin [incobotulinumtoxin A (INCO)] injections given at intervals of 3–6 months may be effective in long term management of masseter hypertrophy and contouring of lower face 30,31 . Prabotulinumtoxin A (PRA) in a dosage of 48–72 units followed by reinjection after 12‐weeks is also effective in a dose‐dependent manner; however, higher doses may lead to discomfort during jaw movement 32 . It is important to note that studies which reported on the use of higher doses of BTA are almost always from Asian countries, especially Korea.…”

“…30,31 Prabotulinumtoxin A (PRA) in a dosage of 48-72 units followed by reinjection after 12-weeks is also effective in a dosedependent manner; however, higher doses may lead to discomfort during jaw movement. 32 It is important to note that studies which reported on the use of higher doses of BTA are almost always from Asian countries, especially Korea. Our experience is that Caucasian patients achieve acceptable results using 15-30 units per side (Figures 2, 3).…”