title: [The effect of bleaching on fracture resistance in human dentin].
abstract: OBJECTIVE
  To study the effect of bleaching on the mechanical properties of human dentin.
  
  
  METHODS
  The finite element method (FEM) based the cohesive zone model had been employed to study the fracture resistance of human dentin. There types of dentin were considered, i.e. original dentin, dentin after direct-bleaching and indirect-bleaching.
  
  
  RESULTS
  The bleaching treatments had large impact on the crack growth resistance of human dentin. The initiation toughness (1.48 MPa x square root of m), growth toughness (3.90 MPa x square root of m x mm(-1)) and plateau toughness (3.25 MPa x square root of m) of human dentin were reduced to 1.29 MPa x square root of m, 3.45 MPa x square root of m x mm(-1) and 2.71 MPa x square root of m respectively after indirect-bleaching. The worst case was the direct-bleaching which causes significant reductions in the growth toughness (0.14 MPa x square root of m x mm(-1)) and plateau toughness (1.63 MPa x square root of m) respectively, while the initiation toughness remained the same as that after indirect-bleaching.
  
  
  CONCLUSIONS
  The cohesive zone modeling is an effective tool in characterizing the fracture behavior of human dentin. Bleaching treatments reduce the crack growth resistance of human dentin and increase the risk of fracture of teeth.
authors.affiliation: Dept. of Stomatology, The Tenth People's Hospital Affiliated to Tongji University, Shanghai 200072, China.
authors.forename: Yuanzhi
authors.initials: Y
authors.lastname: Xu
authors.forename: Raorao
authors.initials: R
authors.lastname: Wang
authors.forename: Bingbing
authors.initials: B
authors.lastname: An
authors.forename: Yinxiao
authors.initials: Y
authors.lastname: Zhou
authors.forename: Haiyang
authors.initials: H
authors.lastname: Yu
authors.forename: Dongsheng
authors.initials: D
authors.lastname: Zhang
mesh_terms: D003804:Dentin; D006801:Humans; D014092:Tooth Root