Fracture Loads of All-Ceramic Crowns under Wet and Dry Fatigue Conditions

Purpose: The aim of this study was to test the hypothesis that fracture loads of fatigued dental ceramic crowns are affected by testing environment and luting cement. Materials and Methods: One hundred and eighty crowns were prepared from bovine teeth using a lathe. Ceramic crowns were prepared from three types of ceramic systems: an alumina-infiltrated ceramic, a lithia-disilicate-based glass ceramic, and a leucite-reinforced ceramic. For each ceramic system, 30 crowns were cemented with a composite resin cement, and the remaining 30 with a resin-modified glass ionomer cement. For each ceramic system and cement, ten specimens were loaded to fracture without fatiguing. A second group (n = 10) was subjected to cyclic fatigue and fracture tested in a dry environment, and a third group (n = 10) was fatigued and fractured in distilled water. The results were statistically analyzed using one-way ANOVA and Tukey HSD test. Results: The fracture loads of ceramic crowns decreased significantly after cyclic fatigue loading (p <= 0.05); furthermore, fracture loads of crowns fatigued in a wet environment were statistically lower than those in a dry environment (p < 0.05). Crowns luted with a composite resin cement showed statistically greater fracture loads than those luted with a resin-modified glass ionomer cement (p <= 0.05). Conclusions: Fracture load of the three ceramic systems was found to be influenced by ceramic composition. Moreover, cement and fatigue condition influenced the fracture loads of the crown specimens evaluated in this study.