title: Effects of botulinum toxin type A on contouring of the lower face.
abstract: BACKGROUND
  Masseteric muscle hypertrophy is an uncommon dition represented as a swelling of the masseter muscle. Recent reports have demonstrated the successful use of botulinum in the treatment of masseteric hypertrophy.
  
  
  OBJECTIVE
  This study was a prospective trial to evaluate the effectiveness of botulinum toxin type A (Botox) in the treatment of masseteric muscle hypertrophy according to doses of 10, 20, and 30 U.
  
  
  METHODS
  Twenty-two patients were referred to the dermatologic clinic for the management of masseteric muscle hypertrophy. Ultrasonographic measurements of the thickness of the masseter muscle were performed, and clinical photographs were taken before treatment and 1, 2, 3, 4, 6, and 9 months after the treatment. RESULTS. The median values of percentage reduction of muscle mass were 10.3%, 16.5%, 23.7%, 24.7%, 21.6%, 16.5% in the 10 U group; 11.9%, 18.8%, 24.8%, 27.7%, 26.7%, and 21.8% in the 20 U group; and 12.0%, 19.4%, 25.0%, 27.8%, 37.8%, and 24.1% in the 30 U group. CONCLUSION. The adequate dose of botulinum toxin type A for treatment of masseteric muscle hypertrophy should be above 20 U. The effect of botulinum toxin type A is maintained for at least 9 months as the treatment of masseteric muscle hypertrophy.
authors.affiliation: Department of Dermatology, College of Medicine, Chung-Ang University, Seoul, South Korea.
authors.forename: Seong Wook
authors.initials: SW
authors.lastname: Choe
authors.forename: Wan Ik
authors.initials: WI
authors.lastname: Cho
authors.forename: Chang Kyun
authors.initials: CK
authors.lastname: Lee
authors.forename: Seong Jun
authors.initials: SJ
authors.lastname: Seo
mesh_terms: D000328:Adult; D019274:Botulinum Toxins, Type A / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D006984:Hypertrophy / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000473:pathology; D015552:Injections, Intralesional; D008297:Male; D008406:Masseter Muscle / Q000000981:diagnostic imaging / Q000187:drug effects / Q000473:pathology*; D009465:Neuromuscular Agents / Q000008:administration & dosage*; D011446:Prospective Studies; D011897:Random Allocation; D016896:Treatment Outcome; D014463:Ultrasonography
chemical_list: D009465:Neuromuscular Agents; D019274:Botulinum Toxins, Type A