title: The effect of pregnancy on orthodontic tooth movement in rats.
abstract: BACKGROUND
  The purpose of this study was to investigate the effect of pregnancy on orthodontic tooth movement in Wistar rats.
  
  
  METHODS
  Forty eight female three-month old Wistar rats with an average weight of 250 ± 25 gr were selected and randomly divided into two experimental (pregnant) and control groups (non-pregnant). Maxillary central incisors were tipped distally by insertion of springs exerting 30 g force. Two, seven and fourteen days after spring insertion animals were sacrificed. Then the mesioincisal distance between maxillary incisors were measured. Subsequently, histological sections were prepared to count osteoclasts under a light microscope. The data on the extent of orthodontic tooth movement, and the number of osteoclasts were analyzed by independent sample t-test.
  
  
  RESULTS
  The results indicated that 2,7 and 14 days after force application there was no significant difference in orthodontic tooth movement between experimental and control groups (p>0.05). The number of osteoclasts were significantly lower in the experimental group 7 and 14 days after spring insertion (p<0.05).
  
  
  CONCLUSIONS
  Pregnancy may decrease the amount of tooth movement in the linear phase but it is not statistically significant. The number of osteoclasts is significantly decreased during pregnancy.
authors.affiliation: Resident of Endodontics, Hamedan University of medical sciences, Hamedan, Iran.
authors.forename: Kavoos
authors.initials: K
authors.lastname: Ghajar
authors.forename: Pooya
authors.initials: P
authors.lastname: Olyaee
authors.forename: Behnam
authors.initials: B
authors.lastname: Mirzakouchaki
authors.forename: Loghman
authors.initials: L
authors.lastname: Ghahremani
authors.forename: Alireza
authors.initials: A
authors.lastname: Garjani
authors.forename: Esmaeil
authors.initials: E
authors.lastname: Dadgar
authors.forename: Sahel
authors.initials: S
authors.lastname: Marjani
mesh_terms: D000818:Animals; D005260:Female; D009967:Orthodontic Appliances; D011247:Pregnancy; D051381:Rats; D017208:Rats, Wistar; D014087:Tooth Movement Techniques