Influence of the veneer-framework interface on the mechanical behavior of ceramic veneers: a nonlinear finite element analysis.
BACKGROUND
The chipping of ceramic veneers is a common problem for zirconia-based restorations and is due to the weak interface between both structures.


OBJECTIVE
The purpose of this study was to evaluate the mechanical behavior of ceramic veneers on zirconia and metal frameworks under 2 different bond-integrity conditions.


METHODS
The groups were created to simulate framework-veneer bond integrity with the crowns partially debonded (frictional coefficient, 0.3) or completely bonded as follows: crown with a silver-palladium framework cemented onto a natural tooth, ceramic crown with a zirconia framework cemented onto a natural tooth, crown with a silver-palladium framework cemented onto a Morse taper implant, and ceramic crown with a zirconia framework cemented onto a Morse taper implant. The test loads were 49 N applied to the palatal surface at 45 degrees to the long axis of the crown and 25.5 N applied perpendicular to the incisal edge of the crown. The maximum principal stress, shear stress, and deformation values were calculated for the ceramic veneer; and the von Mises stress was determined for the framework.


RESULTS
Veneers with partial debonding to the framework (frictional coefficient, 0.3) had greater stress concentrations in all structures compared with the completely bonded veneers. The metal ceramic crowns experienced lower stress values than ceramic crowns in models that simulate a perfect bond between the ceramic and the framework. Frameworks cemented to a tooth exhibited greater stress values than frameworks cemented to implants, regardless of the material used.


CONCLUSIONS
Incomplete bonding between the ceramic veneer and the prosthetic framework affects the mechanical performance of the ceramic veneer, which makes it susceptible to failure, independent of the framework material or complete crown support.
Graduate student, Department of Prosthodontics and Periodontology, Piracicaba Dental School, State University of Campinas, Piracicaba, São Paulo, Brazil.
Priscilla Cardoso
PC
Lazari
Professor, Department of Restorative Dentistry, Juiz de Fora Dental School, Federal University of Juiz de Fora, Minas Gerais, Brazil.
Bruno Salles
BS
Sotto-Maior
Professor, Department of Dental Materials and Prosthodontics, Araçatuba Dental School, São Paulo State University, São Paulo, Brazil.
Eduardo Passos
EP
Rocha
Graduate student, Department of Prosthodontics and Periodontology, Piracicaba Dental School, State University of Campinas, Piracicaba, São Paulo, Brazil.
Germana
G
de Villa Camargos
Professor, Department of Prosthodontics and Periodontology, Piracicaba Dental School, State University of Campinas, Piracicaba, São Paulo, Brazil. Electronic address: altcury@fop.unicamp.br.
Altair Antoninha
AA
Del Bel Cury
D002484:Cementation / Q000379:methods; D002516:Ceramics / Q000737:chemistry*; D017076:Computer-Aided Design; D003442:Crowns; D003722:Dental Alloys / Q000737:chemistry; D001840:Dental Bonding; D015921:Dental Implants; D003764:Dental Materials / Q000737:chemistry*; D017267:Dental Prosthesis Design; D019094:Dental Prosthesis, Implant-Supported; D003801:Dental Veneers; D020342:Finite Element Analysis; D017276:Friction; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D008422:Materials Testing; D016876:Metal Ceramic Alloys / Q000737:chemistry; D017711:Nonlinear Dynamics; D010165:Palladium / Q000737:chemistry; D012834:Silver / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D015040:Zirconium / Q000737:chemistry
D003722:Dental Alloys; D015921:Dental Implants; D003764:Dental Materials; D016876:Metal Ceramic Alloys; D012834:Silver; D010165:Palladium; D015040:Zirconium; C028541:zirconium oxide