Fractographic features of glass‐ceramic and zirconia‐based dental restorations fractured during clinical function

Abstract

Fractures during clinical function have been reported as the major concern associated with all-ceramic dental restorations. The aim of this study was to analyze the fracture features of glass-ceramic and zirconia-based restorations fractured during clinical use. Twenty-seven crowns and onlays were supplied by dentists and dental technicians with information about type of cement and time in function, if available. Fourteen lithium disilicate glass-ceramic restorations and 13 zirconia-based restorations were retrieved and analyzed. Fractographic features were examined using optical microscopy to determine crack initiation and crack propagation of the restorations. The material comprised fractured restorations from one canine, 10 incisors, four premolars, and 11 molars. One crown was not categorized because of difficulty in orientation of the fragments. The results revealed that all core and veneer fractures initiated in the cervical margin and usually from the approximal area close to the most coronally placed curvature of the margin. Three cases of occlusal chipping were found. The margin of dental all-ceramic single-tooth restorations was the area of fracture origin. The fracture features were similar for zirconia, glass-ceramic, and alumina single-tooth restorations. Design features seem to be of great importance for fracture initiation.

Fracture resistance of computer‐aided design/computer‐aided manufacturing‐generated composite resin‐based molar crowns

“…Additionally, it was observed that the primary fracture origin was located at the occlusal surface, regardless of the type of the crowns. By contrast, it has been reported that clinically failed all‐ceramic crowns fractured from the cervical area . Ø ilo et al .…”

“…Additionally, it was observed that the primary fracture origin was located at the occlusal surface, regardless of the type of the crowns. By contrast, it has been reported that clinically failed all-ceramic crowns fractured from the cervical area (43)(44)(45)(46). ØILO et al (33) demonstrated that the clinically relevant fracture mode could be reproduced in the load-to-failure test by using crowns with a clinically relevant curved finish line, dies made of epoxy resin, and the rubber sheet.…”

Fracture load of ceramic restorations after fatigue loading

“…A recent fractographic analysis of clinically fractured restorations reported that the fracture of 5 of 7 molar zirconia crowns originated at the interproximal cervical margin. 25 The authors recommend cushioning the antagonist during in vitro testing to distribute stress evenly, particularly at the cervical margin. 17 A further limitation of this study is the variation in cement thickness that can be observed between the occlusal surface of the tooth preparations and the crowns ( Fig.…”

3D statistical failure analysis of monolithic dental ceramic crowns

“…For higher strength ceramic materials such as lithium disilicate glass-ceramic, zirconia [17] and alumina [18] , failure initiation from the intaglio surface originating in margin area has been reported. While the exact fracture initiation sites appear to depend on specific materials properties, these fractographic studies indicate that the most current ceramic crown failures initiate from the cement interface as opposed to the occlusal surface.…”

“…For example, tooth restoration failure in the cervical margin in approximal area [17] cannot be represented by axisymmetric models. The use of actual crown geometries becomes important in developing experimental and modeling protocol for assessing clinical longevity.…”