Comparing vertical fracture resistance of teeth obturated with two materials

Objectives: Endodontically-treated teeth are more prone to vertical fractures. Various methods have been proposed to increase their resistance. Among these are bonded amalgams, bonded resin composites, and resin-based sealers in addition to new obturation materials (Resilon). This study compared fracture resistance of teeth filled with these materials. Methods: 40 non-carious single-canal premolars were undergone MOD and step-back root canal cavity preparations. They were randomly grouped into 4 groups of 10 each, according to two categories of coronal restoration (amalgam-Panavia F [A]/composite [B]) and obturation (gutta-percha-AH26 [1]/Resilon-Epiphany [2]). These alongside 10 intact control teeth were incubated in 100% humidity (37°C) for a week; then were subjected to compressive forces at 0.5 mm/min crosshead speed to measure fracture loads. Types of fractures (restorable/non-restorable) were evaluated under 32x magnifications. Results: ANOVA revealed a significant difference among all groups (P=0.000). According to Tukey HSD, 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, 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). Groups control, 1A, 2A, 1B, and 2B had 100%, 20%, 30%, 40%, and 40% of restorable fractions. All fractions were significantly lower (P<0.00) than 100% in the control group, according to Fisher exact test. Conclusion: Composite resin restoration may recover the fracture resistance, significantly more than bonded amalgam do. Resilon-Epiphany may have slightly but not significantly superior results regarding fracture resistance.