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

Abstract 

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 Brånemark 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 unpaired t test (α=.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 Al₂O₃ 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.