Objective: This study aims to evaluate fracture formation values of the prefabricated posts supporting the dental crown structure and ensuring its integrity in the application stage of the teeth.

Materials and Methods: Overall, 40 mandibular 1st premolar teeth of similar anatomical shape and dimension with tooth extraction indication were used. The teeth divided into 4 groups with 10 teeth in each group, root canal treatment was applied and afterwards 1 week of waiting interval was included to the study plan. Then the teeth were placed in self-polymerizing acrylic, which was poured into molds forming 3 cm diameter and 2 cm height, where the 2 mm cement enamel junction was exposed. By using Gates Glidden drill, a post-gap suitable for the placement of prefabricated posts in two different diameters and lengths was obtained. Torques were applied manually to the samples placed in the digital torque measuring device, and torque values causing fracture formation were recorded.

Results: While the mean fraction value was the lowest in Group D (8.10 N), the highest fraction value was observed in Group A (14.25 N). In samples with the same post diameter, no statistically significant difference was found when fraction values of the samples were increased. By comparing the fracture values of prefabricated post diameters between 1.25 and 1.50 mm a statistically significant difference was found (P<0.05).

Conclusion: Tooth fractures due to tightening torques can occur in prefabricated post applications and an increase in post diameter use weakens the fracture strength of the teeth.