Evaluation of the Effect of Furcation Perforation on the Fracture Resistance of Endodontically Treated Mandibular Molars

Root perforations are among the most common procedural complications during root canal treatment; these complications have a poor prognosis. This study aimed to evaluate the effect of furcation perforation on the fracture resistance of endodontically treated mandibular molars. Sixty intact extracted mandibular molars were divided into two groups; with a marginal ridge (access only) and without a marginal ridge (MOD and access cavity preparation). The two groups underwent endodontic treatment and were divided into three subdivisions: the first group was prepared without any furcal perforation, the second group had a 1-mm perforation in the furcation area, and the third group was prepared with a 3-mm perforation in the furcation area. The furcation perforation site was filled with calcium hydroxide powder and covered with glass-ionomer (GI). The teeth were restored with posterior composite resin. The teeth were then mounted in acrylic blocks and tested with a Testometric machine under compressive strengths. The fracture resistance diagram of each tooth was drawn. The data were analyzed with two-way ANOVA. The fracture patterns were evaluated after separating the teeth from acrylic blocks. Loss of marginal ridge had no significant effect on fracture resistance measurements (P=0.312), but the furcal perforation variable resulted in significant differences in fracture resistance measurements (P=0.004). Teeth without furcal perforation differed significantly from the teeth with a 3-mm furcal perforation in fracture resistance (P=0.009). The 1-mm furcal perforation group differed significantly from the 3-mm furcal perforation group in fracture resistance (P=0.011). The teeth with a 3-mm furcal perforation exhibited lower fracture resistance than the two other groups.