Fracture Resistance of Endodontically Treated Teeth with Different Perforation Diameters: An In Vitro Analysis

Objectives: The aim of this study was to investigate the relationship between the diameter of iatrogenic root perforations and the fracture resistance (FR) of endodontically treated teeth. Methods: Sixty-five single-rooted teeth were sectioned at 13 mm from the anatomic apex. Their weight and the mesiodistal (MD) and buccolingual (BL) dimensions were recorded in order to ensure their allocation into five homogeneous groups (N = 13); Group 1 (control group): teeth remained intact, Group 2: teeth were instrumented but not perforated, Group 3: teeth were instrumented and perforated with a 2.1 mm bur, Group 4: teeth were instrumented and perforated with a 1 mm bur, and Group 5: teeth were instrumented and perforated with a 0.5 mm bur. All perforations were created at the same spot in the buccal surface of the roots. To further standardize the defects, an apparatus ensured that the cutting bur was positioned with a steady angle of 105° to the external root surface. A universal testing machine was used for fracture testing by applying a compressive vertical load at a speed of 1 mm/min until root fracture. The recorded forces were statistically analyzed with one-way analysis of variance (ANOVA) and post hoc Tukey test. Results: The mean fracture load was 342.68 ± 146.45 N for Group 1, 322.96 ± 98.62 N for Group 2, 214.65 ± 71.32 N for Group 3, 212.66 ± 77.89 N for Group 4, and 307.14 ± 109.16 N for Group 5. However, only the differences between groups 1-3 and 1-4 were statistically significant (p < 0.05). Conclusions: The teeth with 2.1 mm and 1 mm perforations were found to have significantly decreased FR.