title: Mechanical behavior of ceramic veneer in zirconia-based restorations: a 3- dimensional finite element analysis using microcomputed tomography data.
abstract: BACKGROUND
  The fracture or chipping of ceramic veneers is a common problem for zirconia-based restorations.
  
  
  OBJECTIVE
  This study evaluated the stress distribution in the veneer of a maxillary central incisor restored with a complete crown using a zirconia core with a feldspathic ceramic veneer, simulating an incomplete bond between the veneer and zirconia substructure.
  
  
  METHODS
  Based on a microcomputed tomography of a maxillary central incisor, 3 finite element models (M) for a complete crown were developed: Mf, a complete crown based on feldspathic ceramic; Mlz, a zirconia-based complete crown with a complete bond at the zirconia/veneer interface; and Mnzl, similar to Mlz, but with an incomplete bond at the zirconia/veneer interface created by using a contact element with a frictional coefficient of 0.3. A distributed load of 1 N was applied to the lingual surface at 45 degrees to the long axis of the tooth.
  
  
  RESULTS
  The zirconia core in the Mnzl model showed peak stresses for maximum principal stress (σ(max)) and shear stress of 9.02 and 8.81 MPa, respectively. The ceramic veneer in the Mnlz model showed peak stresses for σ(max), minimum principal stress (compressive), and von Mises stresses of 5.4 MPa, 61.23 MPa, and 35.19 MPa, respectively.
  
  
  CONCLUSIONS
  The incomplete bond increased the σ(max) in the ceramic veneer in comparison to the perfect bond condition.
authors.affiliation: Department of Dental Materials and Prosthodontics, Faculty of Dentistry, São Paulo State University (UNESP), Araçatuba, São Paulo, Brazil. eduardo_rocha@foa.unesp.br
authors.forename: Eduardo Passos
authors.initials: EP
authors.lastname: Rocha
authors.forename: Rodolfo Bruniera
authors.initials: RB
authors.lastname: Anchieta
authors.forename: Amilcar Chagas
authors.initials: AC
authors.lastname: Freitas
authors.forename: Erika Oliveira
authors.initials: EO
authors.lastname: de Almeida
authors.forename: Paolo M
authors.initials: PM
authors.lastname: Cattaneo
authors.forename: Ching
authors.initials: C
authors.lastname: Chang Ko
mesh_terms: D000538:Aluminum Silicates / Q000737:chemistry; D003198:Computer Simulation; D003442:Crowns; D001840:Dental Bonding; D003776:Dental Porcelain / Q000737:chemistry*; D019232:Dental Restoration Failure; D003801:Dental Veneers; D055119:Elastic Modulus; D020342:Finite Element Analysis; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D007180:Incisor; D055595:Mechanical Phenomena; D008954:Models, Biological; D011176:Post and Core Technique; D017680:Potassium Compounds / Q000737:chemistry; D013314:Stress, Mechanical; D055114:X-Ray Microtomography; D015040:Zirconium / Q000737:chemistry*
chemical_list: D000538:Aluminum Silicates; D017680:Potassium Compounds; D003776:Dental Porcelain; C016447:feldspar; D015040:Zirconium; C028541:zirconium oxide