title: [Analysis of the fracture processes in all-ceramic crowns by finite element analysis].
abstract: OBJECTIVE
  To analyze the effects of core material and design on the fracture mechanism of veneered all-ceramic crowns.
  
  
  METHODS
  The fracture process of 6 veneered alumina or zirconia crowns with different core design (well-distributed core, not well distributed core, and core with cervical ring) under load was analyzed by RFPA'2D finite element analysis software.
  
  
  RESULTS
  All the six tested crowns fractured due to tension failure, and the crack started at the porcelain in the cusp and spread along the interface between core and porcelain. Under the conditions of this test, the break was only related to the porcelain and not the core, and the crack of porcelain took place earlier in zirconia crowns than in alumina crowns. Minimum stress distribution in cervical ring core design crown and maximum stress distribution in not well distributed core design crown could be seen at the neck area.
  
  
  CONCLUSIONS
  Zirconia crowns presented greater stress at the interface between core and porcelain than alumina crowns. The not well distributed core design did not increase the rise of break. The neck area was the weak area with tensile stress concentration in the cervical ring core design.
authors.affiliation: Department of Prosthodontics, Peking University School and Hospital of Stomatology, Beijing 100081, China.
authors.forename: Yi-hong
authors.initials: YH
authors.lastname: Liu
authors.forename: Hai-lan
authors.initials: HL
authors.lastname: Feng
authors.forename: Yi-wang
authors.initials: YW
authors.lastname: Bao
authors.forename: Yan
authors.initials: Y
authors.lastname: Qiu
mesh_terms: D017267:Dental Prosthesis Design; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D020342:Finite Element Analysis; D008422:Materials Testing; D016876:Metal Ceramic Alloys
chemical_list: D016876:Metal Ceramic Alloys