Influence of different adhesive resin cements on the fracture strength of aluminum oxide ceramic posterior crowns

The influence of different types of adhesive resin cements on the long-term prognosis of aluminum oxide ceramic posterior crowns is unclear. The purpose of this study was to evaluate the fracture resistance of aluminum oxide ceramic on maxillary posterior crowns cemented with different resin luting agents before and after cyclic thermomechanical loading. Forty-eight maxillary first molars were prepared and restored with standardized aluminum oxide ceramic (In-Ceram Alumina) crowns. The test specimens were randomly divided into 3 groups (n=16). The crowns were luted with an acrylic resin cement (Super-Bond C&B, control, Group SB) and 2 composite luting agents (Panavia F, Group PV; and Rely X Unicem, Group RX). Half of the specimens were exposed to thermomechanical fatigue in a masticatory simulator. All specimens were tested for fracture strength (N) using quasistatic loading. The Wilcoxon rank sum test was used to compare the fracture strength (α=.05). All specimens survived the exposure to the simulator. The following median fracture strength values were obtained without/with thermomechanical fatigue loading: Group SB, 2726 N/2673 N; Group PV, 2520 N/2083 N; and Group RX, 2036 N/2369 N. The fracture strength in Group PV after thermomechanical fatigue loading was significantly lower compared to the fracture strength in Group PV without artificial aging ( P=.016), as well as significantly lower compared to Group SB with artificial aging ( P=.003). Within the limitations of this study, all tested cements are capable of successfully luting aluminum oxide ceramic crowns. The fracture strength of Group PV after artificial aging was comparatively low.