Effect of Restoration Strategy and Cavity Location on the Fracture Resistance of Teeth with External Cervical Resorption

Introduction The restoration of external cervical resorption (ECR) defects requires materials capable of withstanding functional stresses. This study aimed to compare the fracture resistance of different restorative approaches applied to buccal versus palatal ECR defects under simulated clinical conditions. Methods Eighty-one extracted human maxillary central incisors were used. Nine intact teeth served as the positive control group (n = 9). The remaining 72 teeth were randomly assigned to standardized buccal or palatal ECR defect groups (n = 36 each). Each subgroup (n = 9) received one of the following treatments: negative control (no restoration), Biodentine alone, Ribbond + Biodentine, or EverX Flow + Biodentine (n = 9 per subgroup). Standardized ECR cavities were created 4 mm apical to the cementoenamel junction, with dimensions of 3 mm in width and 3 mm in depth and connected to the pulp chamber. All specimens underwent chewing simulation (240,000 cycles, 50 N load) and thermocycling (5°C–55°C) prior to fracture testing. The fracture test was performed using a universal testing machine by applying force at a 45° angle, and the maximum load was recorded in Newtons (N). Statistical analysis was performed using parametric or nonparametric tests based on data distribution, with significance set at P < .05. Results The restorative material significantly influenced fracture resistance (P < .05). In buccal defects, the Ribbond + Biodentine group demonstrated significantly higher fracture resistance compared to negative controls. For palatal defects, Biodentine alone showed significantly greater resistance than negative controls. No significant differences were observed between buccal and palatal locations (P > .05). Conclusions While the choice of restorative material had a significant effect on the performance of restorations in ECR defects, the location of the cavity (buccal or palatal) did not significantly influence the outcomes. © 2025 American Association of Endodontists.