title: [Effects of orthodontic tooth movements on serum and local estrogen expression].
abstract: OBJECTIVE
  To investigate the changes of the serum and local estrogen level during orthodontic tooth movements and attempt to elucidate the bio-mechanism of orthodontic treatment.
  
  
  METHODS
  A Wistar rat experimental model was established to apply orthodontic activation during different stages of estrous cycle. One hundred and twenty female rats were randomly divided into sham-operated group, activation group and control group. Each group was further divided into 4 sub-groups according to the different stage of the estrous cycle. The serum and periodontal tissue estradiol level were determined by radioimmunoassay and immunocytochemistry. The data of each group was analyzed with SPSS11.0 software package for Student-Newman- Keuls(S-N-K) test, and cosinor-rhythmometry method was used for chronobiologic analysis to show the rhythmic change of the estrogen level.
  
  
  RESULTS
  Both serum and periodontal estradiol expression were increased by orthodontic activation during various stages of the estrous cycle (P<0.05). But the rhythm of the estradiol level during the estrous cycle was not changed.
  
  
  CONCLUSIONS
  It is concluded that local mechanical stimulation directly enhances the periodontal tissue estrogen expression and inferred that the stress induced by orthodontic activation is related to the serum estrogen augmentation.
authors.affiliation: Department of Orthodontics, School of Stomatology, Peking University, Beijing 100081, China. kqgj@sdu.edu.cn
authors.forename: Jie
authors.initials: J
authors.lastname: Guo
authors.forename: Qing
authors.initials: Q
authors.lastname: Zhao
authors.forename: Yang-xi
authors.initials: YX
authors.lastname: Chen
authors.forename: Xiang-long
authors.initials: XL
authors.lastname: Zeng
mesh_terms: D000818:Animals; D004967:Estrogens / Q000096:biosynthesis*; D030762:Estrous Cycle; D005260:Female; D010519:Periodontium; D051381:Rats; D017208:Rats, Wistar; D014087:Tooth Movement Techniques
chemical_list: D004967:Estrogens