title: [Expression of type III collagen mRNA in rat periodontal ligamemt in response to different occlusal force].
abstract: OBJECTIVE
  To investigate the altered expression level of type III collagen mRNA in the periodontal ligament of rat molar in response to changes in occlusal force.
  
  
  METHODS
  A model of the rat experimental occlusal trauma was established, in which the occlusal surface on the upper first molar of (250+/-20) g male SD rats was approximately 1 mm elevated unilaterally. Another model was establishde, in which the upper first molar was extracted to remove occlusal force against the lower first molar. The rats were perfusion-fixed at 12 h and on the 3rd, 7th, 14th and 30th day after treatment. The prepared sagittal sections were processed to study the expression of type III collagen mRNA in rat periondontal ligament by in situ hynbridization.
  
  
  RESULTS
  Following the bite-raising,the number and the desity of the positive cells of type III collagen mRNA in the periodontal ligament of the lower first molar increased gradually. The expression of type III collagen mRNA was the strongest on the 7th day (124.03 +/- 14.82). Comparde to the normal rats,the expression level of type III collagen mRNA in the periodontal ligament of the lower first molar significantly decreased on the 14th day (63.07 +/- 5.69). When occlusal force was removed the expression level of type III collagen mRNA in the periodontal ligament of the lower first molar showed a rapid decrease. Subsequently, a gradual increase was recognized. Compared to the normal animal,a more significant increase (154.39 +/- 17.61) was detected on the 7th day after occlusal force was removed.
  
  
  CONCLUSIONS
  The results suggest that type III collagen may play important roles in the process of periodontium remodeling against different occlusal force.
authors.affiliation: Department of Stomatology, Tongji Hospital, Tongji University, Shanghai 200065, China.
authors.forename: Xin-Ping
authors.initials: XP
authors.lastname: Fan
authors.forename: Yun-Feng
authors.initials: YF
authors.lastname: Zhao
authors.forename: Wei-Ping
authors.initials: WP
authors.lastname: Liu
authors.forename: Xiao-Qin
authors.initials: XQ
authors.lastname: Zhao
mesh_terms: D000818:Animals; D001732:Bite Force; D024061:Collagen Type III / Q000096:biosynthesis* / Q000235:genetics; D008297:Male; D008963:Molar / Q000378:metabolism; D010513:Periodontal Ligament / Q000378:metabolism*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D024061:Collagen Type III; D012333:RNA, Messenger