title: Change in elastic modulus of bovine dentine with exposure to a calcium hydroxide paste.
abstract: OBJECTIVE
  To determine the effect of calcium hydroxide [Ca(OH)(2)] paste exposure on the elastic modulus of bovine dentine.
  
  
  METHODS
  Dentine sections (4 mm x 4 mm x 1 mm) were obtained from freshly extracted bovine incisors and placed in dishes containing a 1-mm deep layer of Ca(OH)(2) paste or physiological saline as a control. An ultrasonic device was used to measure the sonic velocities of the longitudinal and shear waves, and the elastic modulus was calculated. Data were examined by analysis of variance followed by the Tukey H.S.D. test in order to compare different storage times.
  
  
  RESULTS
  Exposure to Ca(OH)(2) paste significantly increased the mean elastic modulus of the dentine from 16.3 to 22.1 GPa. By contrast, the elastic modulus of the control dentine, which was exposed to physiological saline, remained constant.
  
  
  CONCLUSIONS
  These results demonstrate that exposure to Ca(OH)(2) paste increases the elastic modulus of dentine, thereby making it more prone to fracture.
authors.affiliation: Department of Operative Dentistry, Nihon University School of Dentistry, 1-8-13 Kanda-Surugadai, Chiyoda-ku, Tokyo 101-8310, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Kawamoto
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Kurokawa
authors.forename: Chikako
authors.initials: C
authors.lastname: Takubo
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Shimamura
authors.forename: Takeshi
authors.initials: T
authors.lastname: Yoshida
authors.forename: Masashi
authors.initials: M
authors.lastname: Miyazaki
mesh_terms: D000287:Administration, Topical; D000818:Animals; D001843:Bone Cements / Q000494:pharmacology*; D002126:Calcium Hydroxide / Q000494:pharmacology*; D002417:Cattle; D003804:Dentin / Q000187:drug effects*; D055119:Elastic Modulus / Q000187:drug effects*; D014082:Tooth Fractures / Q000139:chemically induced
chemical_list: D001843:Bone Cements; D002126:Calcium Hydroxide