Fracture resistance of pulpotomized primary molars restored with three types of composite resins with and without fiber-reinforcement

Objective: Coronal restoration of pulpotomized primary molars plays a vital role in ensuring the long-term success of the treatment. This study aimed to evaluate the effect of fiber reinforcement on the fracture resistance of pulpotomized primary molars restored with flowable or paste bulk-fill composite resins in comparison to a conventional composite resin.Methods: In this in vitro experimental study, 48 primary molars were randomly allocated into six groups (n=8). The teeth were pulpotomozed and restored with the following materials: Group 1: Conventional composite resin, Group 2: Fiber+ conventional composite resin, Group 3: Paste bulk-fill composite resin, Group 4: Fiber+ paste bulk-fill composite resin, Group 5: Flowable bulk-fill composite resin, and Group 6: Fiber + flowable bulk-fill composite resin. Fracture resistance was measured by a universal testing machine, and the type of failure was determined. Data were analyzed using two-way ANOVA and Tukey’s post hoc test (α = 0.05).Results: The highest fracture resistance was observed in group 6, whereas the lowest was in group 1. Two-way ANOVA revealed that the fiber reinforcement significantly increased fracture resistance (P<0.001), whereas the type of composite resin had no significant effect on fracture resistance (P=0.182). Most failure modes were restorable, with no significant differences observed between groups (P=0.06).Conclusions: Under the study conditions, fiber reinforcement significantly improved the fracture resistance of pulpotomized primary molars. No significant differences were observed among the three composite resins or in their fracture patterns, implying that the three types of composite resins are suitable for restoring pulpotomized primary molars.