title: [An immunohistochemical study of the effects of excessive fluoride on type I collagen in rat developmental dentine].
abstract: OBJECTIVE
  To study the effects of excessive fluoride on type I collagen in rat developmental dentine.
  
  
  METHODS
  Eighty SD rats, 5 days old, were divided into experimental and control groups, 40 in each group. The experimental group received subcutaneous injection of 0.2% NaF every 4 days (the dose was 2 mg NaF per kg body wt). The same volume of 0.9% NaCl was used in the control. Twenty rats in each group were killed 4 days after the second and the seventh injection respectively. The expression of type I collagen was assayed with immunohistochemical technique.
  
  
  RESULTS
  4 out of 20 rats after two injections showed abnormal distribution of type I collagen (dense stain of collagen in the odontoblast, aggregation of collagen in the dentine and disordered arrangement of collagen in the predentine; All 20 rats after seven injections showed abnormal distribution of type I collagen.
  
  
  CONCLUSIONS
  Excessive fluoride may affect the metabolism of type I collagen in rat developmental dentine.
authors.affiliation: The College of Stomatology, Huaxi, Sichuan University, Chengdu 610041, China.
authors.forename: Yu-qing
authors.initials: YQ
authors.lastname: Hao
authors.forename: Gou-quan
authors.initials: GQ
authors.lastname: Wang
authors.forename: Zhong-ying
authors.initials: ZY
authors.lastname: Niu
authors.forename: Xue-dong
authors.initials: XD
authors.lastname: Zhou
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D024042:Collagen Type I / Q000032:analysis*; D003804:Dentin / Q000737:chemistry / Q000187:drug effects* / Q000254:growth & development; D005459:Fluorides / Q000633:toxicity*; D007150:Immunohistochemistry; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D024042:Collagen Type I; D005459:Fluorides