Evaluation of reliability and failure modes of ceramic crown systems depending on framework design and location of load application

• Grant number: 11/23177-8
• Support type: Regular Research Grants
• Duration: March 01, 2012 - August 31, 2014
• Field of knowledge: Health Sciences - Dentistry - Dental Materials
• Principal researcher: Gerson Bonfante
• Grantee: Gerson Bonfante
• Home Institution: Faculdade de Odontologia de Bauru (FOB). Universidade de São Paulo (USP). Bauru , SP, Brazil

Abstract

The excellent mechanical properties of zirconia make it to be the material of choice for ceramic crowns and posterior fixed prostheses. However, problems still exist related to the chippings. The lack of framework support to porcelain is indicated as a possible cause. This study aims to evaluate through laboratory tests if metallic and ceramic framework with conventional or modified design show statistical difference in reducing mechanical complications, such as chipping or fracture of the porcelain veneer on receiving axial loads in marginal ridges of the first molar inferior crowns. Forty crowns will be manufactured on standardized preparations and divided into four groups: group I (conventional framework Nickel-Chromium), group II (modified framework nickel-chromium), group III (conventional framework Zirconia - ZirCAD IPS Emax) and group IV (modified framework Zirconia - IPS Emax ZirCAD). These crowns will be subjected to cyclic loading in a fatigue machine and submerged in water (1.000.000 cycles or until the fracture - load range at 30-300 N). A stainless steel spherical indenter covered by porcelain (IPS Emax Press) will apply the axial load on the mesial marginal ridge, and after the end of the cycle, it will apply the axial load on the distal marginal ridge of the same crown. The cycling will be interrupted at a prescribed number of loading cycles (125.000) and crowns will be inspected for damage accumulation under a stereomicroscope. In the end, fractured crowns will be submitted to scanning electron microscopy and crowns without fractures will be embedded in epoxy resin and sequentially polished for the analysis of the damage. Each sample will receive scores according to the type of failure presented. The Kruskal-Wallis test will be used to verify differences, and the Miller test will be used for multiple comparisons between groups. (AU)

Scientific publications

(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)

FARDIN, VINICIUS P.; BONFANTE, ESTEVAM A.; COELHO, PAULO G.; JANAL, MALVIN N.; TOVAR, NICK; WITEK, LUKASZ; BORDIN, DIMORVAN; BONFANTE, GERSON. Residual stress of porcelain-fused to zirconia 3-unit fixed dental prostheses measured by nanoindentation. Dental Materials, v. 34, n. 2, p. 260-271, FEB 2018. Web of Science Citations: 4.

FARDIN, VINICIUS P.; DE PAULA, VITOR GUARCONI; BONFANTE, ESTEVAM A.; COELHO, PAULO G.; BONFANTE, GERSON. Lifetime prediction of zirconia and metal ceramic crowns loaded on marginal ridges. Dental Materials, v. 32, n. 12, p. 1543-1554, DEC 2016. Web of Science Citations: 5.