Abstract

LORENZONI, Fabio Cesar et al. Influence of modified framework design in all-ceramic and metal-ceramic crowns fatigue life and failure mode. Innov. Implant. J., Biomater. Esthet. (Online) [online]. 2010, vol.5, n.1, pp. 22-28. ISSN 1984-5960.

To evaluate the effect of framework design on the fatigue life and failure modes of metal-ceramic and glass-infiltrated alumina. Forty composite resin tooth-replica of a prepared maxillary first molar were produced to receive crowns of a standard or modified framework design. Core design modification consisted of a standard, connecting to proximal struts. R-ratio fatigue loading was delivered with a spherical steel indenter (3.18 mm radius) on the center of the occlusal surface at a 30-300 N load range, until completion of 106 cycles or failure. Fatigue was interrupted every 125.000 cycles for damage evaluation. Catastrophic fracture, chipping within veneering porcelain, or inner cone crack reaching the core-veneer interface were the criteria for failure. Fractured and polished surfaces were characterized under light polarized microscopy followed by scanning electron microscopy. Weibull distribution fit was used for examining differences between groups. The highest fatigue life was observed for metal-ceramic crowns, but no significant differences were observed for groups with or without framework design modification. Failure modes of metal-ceramic comprised inner cone cracks without porcelain fracture. Glass-infiltrated alumina standard crowns presented bulk fracture whereas glass-infiltrated alumina modified crowns failed mainly through veneer. Fatigue life was not improved with framework design modification. Failure modes varied according to core material.

Keywords : Ceramics; Tooth crown; Dental prosthesis.