AbstractBackground/purposeVarious methods were proposed to increase the fracture resistance of endodontically treated teeth. This study comparatively evaluated the fracture resistance of teeth restored with two obturation and two filling systems.Materials and methodsForty noncarious single-canal premolars underwent MOD and step-back root-canal cavity preparations. They were randomly divided into four groups of 10 teeth each, according to two categories of coronal restoration (amalgam-Panavia F [A] and composite [B]) and obturation (gutta-percha-AH26 [1] and Resilon-Epiphany [2]). These premolars along with 10 intact control teeth were incubated in 100% humidity (37°C) for 1 week, and then were subjected to compressive forces at a 0.5-mm/min crosshead speed to measure fracture loads. Types of fractures (restorable or nonrestorable) were evaluated under 32× magnification.ResultsAn ANOVA revealed a significant difference among all groups (P=0.000). According to Tukey's honest significant difference test, there were significant differences only between Groups 1B and 1A, and between 2B and 2A (those restored with amalgam compared to those restored with composite). However, an independent-samples t test revealed a significant difference between 1A and 2A as well (gutta-percha-AH26 and Resilon-Epiphany restored with amalgam, P=0.027).ConclusionsComposite-resin restorations may recover significantly more fracture resistance than those bonded with amalgam. Resilon-Epiphany may have slightly but not significantly superior results in terms of fracture resistance.