title: [Expression of MMP-2 in the periodontal tissues with the mini-screw for molar intrusion with cyclic intrusive force in dogs].
abstract: OBJECTIVE
  To observe the expression of MMP-2 in the periodontal tissues of molars in Beagle dogs after different times of intrusion by mini-screw with cyclic intrusive force.
  
  
  METHODS
  Three mature Beagle dogs were used for the experiment. On the buccal and palatal sites of the left maxillary second and third premolars, a minis-crew was placed at the inter-radicular septa separately, intruding the tooth with 150 g initial force, which would be reinforced every 4 weeks. The teeth of left side as the experimental group were divided into 3 subgroups, as being intruded 12, 24 and 36 weeks, and the right side as blank control. Then the dogs were sacrificed, and the second and the third premolars with the surrounding periodontal tissue were cut down, fixed, decalcified, wrapped and cut into slices. Immunohistochemical staining with MMP-2 was performed. The average optical density (OD) of MMP-2 was calculated with IPP software, which represented the expression of MMP-2. SPSS 17.0 software package was used for statistical analysis.
  
  
  RESULTS
  Immunohistochemical staining revealed that the expression of MMP-2 in control group was low. After tooth intrusion, MMP-2 expression significantly increased in the periodontal tissues of molars, and reached the maximum in the group of 24 weeks. Then MMP-2 expression decreased in the 36-week group but still significantly higher than the control group. There was no significant difference among the 3 subgroups for different intrusion times(P>0.05).
  
  
  CONCLUSIONS
  MMP-2 participates in remodeling of the periodontal tissue during tooth intrusion. The expression of MMP-2 is not significantly increased with the extension of the intrusion time with cyclic intrusive force, which suggests that with the use of mini-screw to intrude the molars with cyclic intrusive force, the periodontal tissues of the intruded tooth maintain dynamic balance of bone remodeling.
authors: School of Stomatology, Jilin University. Changchun 130021, Jilin Province, China.E-mail:gumengjie198909@126.com.
authors: Meng-Jie
authors: MJ
authors: Gu
authors: Bai-Juan
authors: BJ
authors: Gong
authors: Xin-Hua
authors: XH
authors: Sun
authors: En-Hui
authors: EH
authors: Wang
authors: Bing
authors: B
authors: Zhang
authors: Han
authors: H
authors: Sun
mesh_terms: D000818:Animals; D001641:Bicuspid; D016723:Bone Remodeling; D001863:Bone Screws; D004285:Dogs; D020778:Matrix Metalloproteinase 2; D008437:Maxilla; D008963:Molar; D010519:Periodontium; D018677:Tooth Injuries; D014087:Tooth Movement Techniques
chemical_list: D020778:Matrix Metalloproteinase 2