title: [The use of botulinum toxin type A in masseter muscle hypertrophy: long-term effects and lasting improvement].
abstract: OBJECTIVE
  In this study, we aimed to evaluate the long-term efficacy of botulinum toxin A injection in reducing the masseter muscle thickness.
  
  
  METHODS
  Between 2007 and June 2008, we retrospectively analyzed the data from 28 patients (21 females, 7 males; mean age: 25.5±4.5 years; range 20 to 46 years) with benign masseter hypertrophy treated with botulinum toxin A injections. All patients were diagnosed by the morphometric analysis of the masseter muscle. The injections were repeated intermittently every six months and totally for six times. The patients were recalled and the last measurement was performed at a mean follow-up of 13.2 months.
  
  
  RESULTS
  The values obtained following consecutive injections were compared and a statistically significant reduction in thickness of masseter muscle thickness after every single injection was found (p<0.001). The final measurement following treatment discontinuation revealed that this reduction was long-lasting.
  
  
  CONCLUSIONS
  Botulinum toxin A injection is a safe and long-term effective therapy for the masseter muscle hypertrophy.
authors.affiliation: İstanbul University Faculty of Dentistry, Department of Oral Surgery, İstanbul, Turkey. barisaydil@yahoo.com
authors.forename: Barış
authors.initials: B
authors.lastname: Aydil
authors.forename: Bora
authors.initials: B
authors.lastname: Başaran
authors.forename: Selin
authors.initials: S
authors.lastname: Unsaler
authors.forename: Yusufhan
authors.initials: Y
authors.lastname: Süoğlu
mesh_terms: D000328:Adult; D019274:Botulinum Toxins, Type A / Q000627:therapeutic use*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006984:Hypertrophy / Q000188:drug therapy*; D008297:Male; D008406:Masseter Muscle / Q000002:abnormalities*; D008875:Middle Aged; D009465:Neuromuscular Agents / Q000627:therapeutic use*; D012189:Retrospective Studies; D013997:Time Factors; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D009465:Neuromuscular Agents; D019274:Botulinum Toxins, Type A