title: [Analysis of reliability of the strength of all-ceramic crown on mandibular first molar].
abstract: OBJECTIVE
  To analyze the reliability of all-ceramic crown on mandibular first molar under randomized biting force, and to explore the failure possibility of all-ceramic crown.
  
  
  METHODS
  Finite element (FE) models of all-ceramic crown on mandibular first molar were established using the Algor FE software. All-ceramic crown was loaded at different occlusal areas and positions with random variables of biting force, and the reliability of all-ceramic crown was analyzed.
  
  
  RESULTS
  The occlusal contact positions were located on the fossa, inclined surface and dental cusp. When the occlusal contact area was 0.4 mm(2), The reliability of all-ceramic crown on mandibular first molar were 100% (fossa), 99% (inclined surface), and 97% (cusp) respectively. When the occlusal contact area was 1.5 mm(2), the reliabilities of all-ceramic crown on mandibular first molar were 100% (fossa), 100% (inclined surface), and 99% (cusp) respectively. When the occlusal contact area was increased to 12.6 mm(2), the reliability of all-ceramic crown was 100%.
  
  
  CONCLUSIONS
  Premature occlusal contact and steep cusp inclination on all-ceramic crown on mandibular first molar will result in stress concentration and the crown will exhibit high failure probabilities. Chewing hard food is another contributing factor to the failure of all-ceramic crowns.
authors.affiliation: Department of Prosthodontics, College of Stomatology, The Fourth Military Medical University, Xi'an 710032, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.forename: Shao-feng
authors.initials: SF
authors.lastname: Zhang
authors.forename: Jian-jun
authors.initials: JJ
authors.lastname: Chen
mesh_terms: D001732:Bite Force; D002516:Ceramics / Q000737:chemistry*; D003442:Crowns; D003799:Dental Stress Analysis; D020342:Finite Element Analysis; D006801:Humans; D008334:Mandible; D008409:Mastication; D008963:Molar; D011475:Prosthesis Failure; D015203:Reproducibility of Results; D013718:Tensile Strength