Evaluation of the Adhesive Strength of Different Types of Fiberglass Posts in Flared and Unflared Canal Roots

Introduction Fiberglass posts are used in the rehabilitation of endodontically treated teeth, and adaptation to the canal is a determining factor. Objective This study aimed to evaluate the Push-out Bond Strength (PBS) and failure mode of different types of fiberglass posts, associated or not with a fiberglass sleeve (Exacto and Splendor SAP) in different types of canals (enlarged and non-enlarged canals). Method and Materials Forty bovine roots were used, and the samples were divided into four groups (n=10). The canals were instrumented in a standardized manner. The samples were cemented with dual self-adhesive resin cement. The roots were sectioned in the coronal, middle, and apical thirds with a thickness of 1 mm. The Push-out Bond Strength (PBS) test was performed in a universal testing machine (EMIC). Statistical analysis: PBS values were recorded, and data were analyzed using repeated measures, such as ANOVA and Tukey's test. To determine the failure mode, a stereomicroscope with 40× magnification and 2.5D analysis was used. Results SPrFl showed significantly higher bond strength in the coronal third than SPr and Exc. However, SPr, Exc, and ExcFl did not show any differences between them. Furthermore, similar bond strength was observed between SPrFl and ExcFl. The failure mode was not influenced by the post system (p=0.144) or root third (p=0.146). All experimental groups showed a prevalence of adhesive failures (Types I, II, and III). Conclusion The groups that used the Splendor system showed similar results to conventional posts anatomized with resin, but in the middle and apical thirds, there was no statistical difference in PBS. Clinical Significance The results of this laboratory test can help the dentist to answer which types of fiberglass can be used to rehabilitate endodontically treated teeth, ensuring good adhesive resistance and, consequently clinical success.