Fatemah Khajehzadeh - Private Practice, Yasuj, Iran
Fatemeh Raoufinejad - Department of Restorative Dentistry, School of Dentistry, Qazvin University of Medical Sciences, Qazvin, Iran
Hedayat Gorjestani - Private Practice, Kerman, Iran
Marzie Kamali - Department of Endodontics, School of Dentistry, Kerman University of Medical Sciences, Kerman, Iran
Ali Eslambol Nassaj - Department of Endodontics, School of Dentistry, Kerman University of Medical Sciences, Kerman, Iran
Arash Shahravan - Endodontology Research Center, Kerman University of Medical Sciences, Kerman, Iran

Background: 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.Method: 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 ۱-mm perforation in the furcation area, and the third group was prepared with a ۳-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.Results: Loss of marginal ridge had no significant effect on fracture resistance measurements (P=۰.۳۱۲), but the furcal perforation variable resulted in significant differences in fracture resistance measurements (P=۰.۰۰۴). Teeth without furcal perforation differed significantly from the teeth with a ۳-mm furcal perforation in fracture resistance (P=۰.۰۰۹). The ۱-mm furcal perforation group differed significantly from the ۳-mm furcal perforation group in fracture resistance (P=۰.۰۱۱).Conclusion: The teeth with a ۳-mm furcal perforation exhibited lower fracture resistance than the two other groups.

Fracture resistance, Marginal ridge, Perforation