Influence of the retropreparation ultrasonic insert type on the adhesive union of fiberglass posts within the root canal

To assess the displacement resistance of cemented fiberglass posts within the root canal, based on the type of ultrasonic retropreparation insert used during endodontic surgery. Material and methods: Thirty primary bovine incisor roots, measuring 17 mm in length, underwent endodontic treatment. After a seven-day period, the teeth were debrided and prepared to receive 13 mm posts. The roots were randomly divided into three groups, depending on the type of ultrasonic retropreparation insert used: GC – no retropreparation (control); GL – smooth insert; GD – diamond insert. The posts were cemented using RelyX U200® within the root canal. Subsequently, the roots were immersed in distilled water for 15 days and then sectioned to create specimens with an average thickness of 1.87 mm in each of the root thirds (cervical and middle). These specimens were subjected to a push-out test. Following the test, the fractured samples were examined under a stereomicroscope to determine the fracture pattern. The data obtained were analyzed using a one-way Anova test and non-parametric t-test (α = 0.05). Results: There were no statistically significant differences in the cervical third when comparing the tested ultrasonic inserts. However, in the analysis of the middle third, the use of a smooth ultrasonic insert had a significant impact on the adhesion of the intraradicular post (P < 0.05). Conclusion: The application of a smooth ultrasonic insert during endodontic retropreparation significantly influenced the displacement resistance of intraradicular fiberglass posts cemented in the middle third of the canal. In the cervical third, the type of ultrasonic retropreparation insert used did not affect post retention.