Validation of the novel masseter muscle hypertrophy scale in Asian population

Abstract

Dear editor,There is a growing stream of demands for lower face contouring treatments for oval-and almond-shaped jaws among Asian populations. 1 Among various treatment options, botulinum toxin type A (BoNT-A) injection for masseter muscle hypertrophy (MMH) is an increasingly soughtafter noninvasive and easy treatment option for lower face contouring. 2

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

“…Many physicians make standardized photographs with the muscles relaxed and with patients grinding or serial photographs to document the effects of treatment [ 26 , 33 , 35 ]. Monitoring and documenting the effects of treatment is particularly important because there is only one scale to classify masseteric hypertrophy and cosmetic results of its treatment [ 4 ]. Shear wave elastography has not been used for this purpose.…”

“…In the literature, masseter muscle hypertrophy is often described as a concomitant condition to the hypertrophy of other masticatory muscles, as this condition affects masseteric and temporalis muscles [ 1 ] or even medial pterygoid hypertrophy [ 2 ]. Patients with unilateral masseter muscle hypertrophy are often consulted by an esthetic surgeon due to face asymmetry [ 3 , 4 ]. Bilateral enlargement of the masseter muscles is more common, but constitutes a smaller esthetic problem maintaining the symmetry of the face [ 1 ]; however, it is more often associated with other symptoms, such as bruxism [ 2 , 5 ], temporomandibular disorders, malocclusion, pain, otalgia, nighttime trismus [ 6 ], emotional stress [ 1 , 3 , 6 ], and oral parafunctions, including unilateral chewing and excessive chewing gum [ 2 , 7 ].…”

“…Masseter muscle hypertrophy is rare in children [ 15 ]. The incidence of masseter muscle hypertrophy is considered higher in Asians who are, at the same time, more sensitive about their lower face contouring [ 4 ].…”

Efficacy and Safety of PrabotulinumtoxinA in Subjects With Benign Masseteric Hypertrophy: A Double-Blind, Randomized, Placebo-Controlled, Multicenter, Phase 3 Trial and Open-Label Extension Study

“…We used the masseter muscle hypertrophy scale (MMHS) to evaluate the overall MMH degree, with grades ranging from 1 (minimal) to 5 (very marked). 6 The duration of treatment response was determined as the time it took the subjects whose “severity was MMHS ≥4” and “thickness of the masseter muscle at the maximal clenching was ≥14 mm for males or ≥12 mm for females after 12 weeks.” In addition, the participants were asked to rate their satisfaction on a scale of 1 (very dissatisfied), 2 (dissatisfied), 3 (somewhat dissatisfied), 4 (neutral), 5 (somewhat satisfied), 6 (satisfied), or 7 (very satisfied). We defined “satisfaction” in the case of grades 6 and 7.…”