In vivo fracture resistance of implant-supported all-ceramic restorations

Statement of problem. Because of their specific mechanical properties, all-ceramic restorations demonstrate a lower fracture resistance than ceramic restorations supported by metal substructures. However, advances have been made in the fabrication of high-strength all-ceramic abutments for anterior implants. No previous study has compared the fracture loads between 2 different all-ceramic abutments restored by glass-ceramic crowns. Purpose. The purpose of this in vitro investigation was to quantify, the fracture load of implanted-supported Al2O3 and ZrO2 abutments restored with glass-ceramic crowns. Material and methods. Two ceramic abutments were tested: an Al2O3 abutment (CerAdapt) and a ZrO2 abutment (Wohlwend Innovative). The abutments (n = 10) were placed on Branemark dental implants and prepared for restoration with glass-ceramic crowns (IPS Empress). After fabrication, in accordance with the manufacturer's guidelines, the crowns were bonded to the all-ceramic abutments with a dual-polymerizing resin luting agent. The fracture loads (N) were determined by force application at an angle of 30 degrees by use of a computer-controlled universal testing device. The data were analyzed with the impaired t test (alpha = .05). Results. Statistical analysis showed significant differences between both groups (P = .001) of all-ceramic abutments, with mean fracture load values of 280.1 N ( +/- 103.1) for the A1(2)O(3) abutments and 737.6 N ( +/- 245.0) for the ZrO2 abutments. Conclusion. Within the limitations of this study, both all-ceramic abutments exceeded the established values for maximum incisal forces reported in the literature (90 to 370 N). The ZrO2 abutments were more than twice as resistant to fracture as the Al2O3-abutments.