title: [Characteristics of experimental occlusal interference-induced masticatory mechanical hyperalgesia of rats].
abstract: OBJECTIVE
  To investigate the relationship between the existence of occlusal interference and masticatory muscle hyperalgesia by exploring the stimulus-response relationship between the duration of occlusal interference and masticatory muscle mechanical withdrawal threshold.
  
  
  METHODS
  Occlusal interference with 0.4 mm-thick crowns on rat molars was removed under anaesthesia at 2, 3, 4, 5, and 6 d after wear, and masticatory muscle mechanical withdrawal threshold was tested at 1, 3, 5, 7, 10, 14, 21 and 28 d.
  
  
  RESULTS
  Decreased mechanical withdrawal thresholds were detected in temporal muscles and masseter muscles on both sides following occlusal interference (P < 0.05). After removal of crowns at 2, 3, 4 and 5 d, rats exhibited the similar head withdrawal thresholds as the sham-application control in masticatory muscles on both sides at 10, 14, 14 and 21 d (P > 0.05). No significant differences were detected between the contralateral side with the ipsilateral side (P < 0.05). After removal of crowns at 6 d, rats still exhibited significantly decreased head withdrawal thresholds[right temporal muscle: (1.365±0.018) N; right masseter: (1.437 ± 0.024) N] in masticatory muscles on both sides until the last day of the experiment[the sham-application control: right temporal muscle: (1.554±0.040) N, P < 0.001; right masseter: (1.546±0.019) N, P < 0.001].
  
  
  CONCLUSIONS
  The mechanical hyperalgesia can disappear after removal of the occlusal interference at 5 d, and the existence of the occlusal interference is positively correlated with the duration of the mechanical hyperalgesia.
authors.affiliation: Department of Prosthodontics, Center for Oral and Jaw Functional Diagnosis, Treatment and Research, Peking University School and Hospital of Stomatology, Beijing 100081, China.
authors.forename: Xuejiao
authors.initials: X
authors.lastname: Li
authors.affiliation: Department of Prosthodontics, Center for Oral and Jaw Functional Diagnosis, Treatment and Research, Peking University School and Hospital of Stomatology, Beijing 100081, China.
authors.forename: Ye
authors.initials: Y
authors.lastname: Cao
authors.affiliation: Department of Prosthodontics, Center for Oral and Jaw Functional Diagnosis, Treatment and Research, Peking University School and Hospital of Stomatology, Beijing 100081, China. Email: xieqiuf@163.com.
authors.forename: Qiufei
authors.initials: Q
authors.lastname: Xie
mesh_terms: D000818:Animals; D006930:Hyperalgesia / Q000503:physiopathology*; D008406:Masseter Muscle / Q000503:physiopathology*; D008410:Masticatory Muscles; D008963:Molar; D051381:Rats; D013703:Temporal Muscle / Q000503:physiopathology*