title: [Influences of orthodontic tooth movement on estrous cycle and estrogen in rats].
abstract: OBJECTIVE
  To explore the influences of orthodontic tooth movement on estrous cycle and estrogen in female rats.
  
  
  METHODS
  Two hundred female rats were divided into control group, one-time activation group, four-time activation group and sham-operated group. Each group was divided again into 4 sub-groups according to the different stage of the estrous cycle. The force-loading groups received repeated intermittent force. Serum estrogen was measured and the change of estrous cycle was recorded.
  
  
  RESULTS
  There were significant variations in the estrogen level among the groups which received mechanical force during the same stage of the estrous cycle (P < 0.01) and among the subgroups within each group (P < 0.05). These experimental treatments affected the estrous cycle of the rats in the groups received force in metestrus and diestrus.
  
  
  CONCLUSIONS
  Estrus of rats was the appropriate time for the orthodontic force.
authors.affiliation: Department of Orthodontics, West China School of Stomatology, Sichuan University, Chengdu 610041, China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Zhao
authors.forename: Zhen
authors.initials: Z
authors.lastname: Tan
authors.forename: Jie
authors.initials: J
authors.lastname: Guo
authors.forename: Yang-xi
authors.initials: YX
authors.lastname: Chen
mesh_terms: D000818:Animals; D004967:Estrogens / Q000097:blood*; D030762:Estrous Cycle / Q000502:physiology*; D005260:Female; D051381:Rats; D017208:Rats, Wistar; D014087:Tooth Movement Techniques
chemical_list: D004967:Estrogens