| 0887 Non-linear stress distribution on dentin/laminate veneer interface | ||
|
E.P. ROCHA, Araçatuba School of Dentistry, São Paulo State University - UNESP, Chapel Hill, NC, USA, C.-C. KO, University of North Carolina, Chapel Hill, USA, M.A. LUERSEN, Technological Federal University of Paraná, Curitiba, Paraná, Brazil, D. FORD, The University of North Carolina at Chapel Hill, USA, and M. MARTIN, Jr., Araçatuba School of Dentistry, State University of São Paulo - UNESP, Araçatuba, São Paulo, Brazil OBJECTIVES: There is a general consensus that stiffness of porcelain may affect the failure rate of bonded veneers. We hypothesize that high failure may result from adverse interfacial stresses failing to retain the veneer onto the dentin surface. This study, therefore, investigated stress distribution along the cement layer between dentin/veneer interfaces in a maxillary central incisor for three veneer systems of varying stiffness by manufacture process. Three commercially available veneers, Feldspate(F), IPS Empress Esthetics(E), and Laminate Procera(P) were used to represent refractory, pressed, and machining process, respectively. METHODS: Two-dimensional finite element (FE) analysis was employed to simulate various bonding and loading conditions. FE models were constructed using AutoCAD 2005 software. Young's moduli (E) of the three veneers were adapted from the literature with E= 70 GPa, 65 GPa, and 350 GPa for F, E, and P, respectively. Fully bonded and partially debonded dentin/veneer interfaces were simulated. Two different loads, one to the lingual third and the other to the incisor edge, were investigated; both loads were oriented 45° to the long axis of the incisor. Appropriate boundary conditions were assigned on the border of alveolar bone. Ansys® software was used to compute stress fields. RESULTS: Results showed that porcelain stiffness did affect interfacial stresses when the interface was fully bonded. The maximum tensile stress σmax of P veneer at the cervical finishing line, but not F and E veneers, might exceed the ultimate tensile strength of the luting cement. Stiffness and loading point had little effect on stress values in the debonded interface. CONCLUSION: Poor retention of P veneer may be attributed not only to its lower adhesive potential to its non-modified surface, but also to its high interfacial stress. Future studies investigating effects of laminated structure and incisor reduction are underway. (Supported by CAPES 2325-05-5) | ||
| Seq #107 - Ceramics: Mechanical Properties and Marginal Fit 3:30 PM-4:45 PM, Thursday, March 22, 2007 Ernest N. Morial Convention Center Exhibit Hall I2-J | ||
|
Back to the Dental Materials: III - Ceramics and Cements Program
| ||