title: Change of distribution and timing of bite force after botulinum toxin type A injection evaluated by a computerized occlusion analysis system.
abstract: OBJECTIVE
  The aim of this study was to determine the force distribution and pattern of mastication after injection of botulinum toxin type A (BTX-A) into both masseter muscles. The hypothesis to be tested was that the difference between right and left balance of occlusal force diminishes over time following BTX-A injection.
  
  
  METHODS
  Fifteen patients were submitted to BTX-A injection therapy for subjective masseter hypertrophy. A total of 25 U of BTX-A (50 U in total) was injected into two points located 1 cm apart at the center of the lower one-third of both masseter muscles. All patients were examined using the T-Scan occlusion analysis system before and 4, 8, 12, and 24 weeks after BTX-A injection.
  
  
  RESULTS
  A significant change in force balance was found between the right and left sides over time and the difference between the two sides decreased with the time post-injection, reaching a minimum at 12 weeks. Comparison of the force balance between the anterior and posterior occlusions revealed no significant difference at any of the time points. The occlusion and disclusion times (right and left sides) did not differ significantly with time since BTX-A injection.
  
  
  CONCLUSIONS
  A decline in the difference in the clenching force between the left and right sides was found with increasing time up to 12 weeks following BTX-A injection.
authors: Department of Orofacial Pain and Oral Medicine, College of Dentistry, Yonsei University, Seoul, Korea.
authors: Ji Hee
authors: JH
authors: Song
authors: Department of Orofacial Pain and Oral Medicine, College of Dentistry, Yonsei University, Seoul, Korea.
authors: Eunae S
authors: ES
authors: Cho
authors: Department of Orofacial Pain and Oral Medicine, College of Dentistry, Yonsei University, Seoul, Korea.
authors: Seong Taek
authors: ST
authors: Kim
authors: Department of Orofacial Pain and Oral Medicine, College of Dentistry, Yonsei University, Seoul, Korea. hjahn@yuhs.ac.
authors: Hyung Joon
authors: HJ
authors: Ahn
mesh_terms: D001732:Bite Force; D019274:Botulinum Toxins, Type A / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D005260:Female; D006801:Humans; D006984:Hypertrophy / Q000188:drug therapy; D007267:Injections; D008297:Male; D008406:Masseter Muscle / Q000002:abnormalities / Q000187:drug effects; D009465:Neuromuscular Agents / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use
chemical_list: D009465:Neuromuscular Agents; D019274:Botulinum Toxins, Type A
keywords: Botulinum toxin type A; bite force; dental occlusion; masseter muscle; mastication; time factors