title: [Effect of local injection of rhTGF-α1 on osteoclasts during orthodontic tooth movement in rats].
abstract: OBJECTIVE
  To investigate the effect of exogenous TGF-β1 on improving periodontal tissues remodeling during orthodontic tooth movement in rats.
  
  
  METHODS
  Eighty male SD rats were randomly divided into 2 groups. Rats in the experimental group were injected respectively with rhTGF-β1 in dosages of 0.1 mL (5 ng/mL) in the buccal submucosal area of the molar every other day, while rats in the control group received equivalent volumes of PBS. Each group (n=40) was subdivided equally into 5 subgroups. An orthodontic appliance, consisting of a 5 mm nickel titanium closed coil spring, was ligated between the maxillary left incisor and first molar of each rat to deliver an initial force of 0.49N. Eight rats in each subgroup were sacrificed at one of the five time points (1, 4, 7, 10 and 14 days) after appliance placement. The distance of the tooth movement was measured by using stereomicroscope. Tissue sections around the first maxillary left molar were stained with tartrate-resistant acid phosphatase (TRAP) histochemistry to analyze the changes of the amount and distribution of osteoclasts on the compression side of tooth. Statistical analysis was performed using SPSS 17.0 software package.
  
  
  RESULTS
  Molars treated with rhTGF-β1 moved mesially more rapidly than the control group. The distance of tooth movement of the experimental group showed a significant increase compared with the control group at day 7 (P<0.05) and significant increase compared with the control group at day 10 and 14 (P<0.01). The number of TRAP positive cells appearing in the periodontal ligament space on the pressure side of the alveolar bone were increased markedly in experimental group. There were statistically significant differences in the amount of osteoclasts between experimental and control groups (P<0.01).
  
  
  CONCLUSIONS
  Local injection of rhTGF-β1 in the periodontal tissues can accelerate orthodontic tooth movement via enhancing the numbers of osteoclasts. At the histologic level, increased numbers of mononuclear osteoclasts are recruited and activated, resulting in greater amounts of alveolar bone resorption on the pressure side of the periodontal ligament.
authors.affiliation: Department of Dentistry, The Fifth Affiliated Hospital of Zunyi Medical College. Zhuhai 519100, Guangdong Province;China.E-mail:xyhong-81@163.com.
authors.forename: Yu-hong
authors.initials: YH
authors.lastname: Xu
authors.forename: Gao-hua
authors.initials: GH
authors.lastname: Li
authors.forename: Jian-guo
authors.initials: JG
authors.lastname: Liu
authors.forename: Xiao-yan
authors.initials: XY
authors.lastname: Guan
mesh_terms: D016301:Alveolar Bone Loss; D000818:Animals; D006801:Humans; D007180:Incisor; D008297:Male; D008437:Maxilla; D008963:Molar; D009532:Nickel; D009967:Orthodontic Appliances; D010010:Osteoclasts; D010513:Periodontal Ligament; D010519:Periodontium; D051381:Rats; D017207:Rats, Sprague-Dawley; D014025:Titanium; D014087:Tooth Movement Techniques; D016211:Transforming Growth Factor alpha
chemical_list: C587886:TGFA protein, human; D016211:Transforming Growth Factor alpha; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium