Effect of Hydrofluoric Acid, Silane, and Air Abrasion Surface Treatments on the Tensile Bond Strength and Failure Pattern of Glass Fiber Posts: An In Vitro Study

Introduction: The long-term success of endodontically treated teeth restored with glass fiber posts depends mainly on adequate post-retention. Surface treatment of fiber posts may enhance the bonding between the post and resin cement. The aim of the present study was to evaluate the effect of hydrofluoric acid, a silane coupling agent, and air abrasion with 50 µm alumina particles on the tensile bond strength and failure pattern of glass fiber posts. Materials and methods: Eighty extracted single-rooted mandibular premolars were endodontically treated and prepared for post-placement. Glass fiber posts were divided into four groups (n = 20): hydrofluoric acid treatment (Group 1), silane application (Group 2), air abrasion with 50 µm alumina particles (Group 3), and distilled water (control as Group 4). The posts were cemented using dual-cure resin cement. After storage, the specimens were subjected to tensile testing using a universal testing machine with a crosshead speed of 3 mm/min. Failure modes were analyzed using a stereomicroscope. Data were analyzed using one-way analysis of variance (ANOVA) and Tukey’s post-hoc test at a significance level of p < 0.05. Results: The hydrofluoric acid group exhibited the highest mean tensile bond strength (240.12 ± 88.00 MPa), followed by the air abrasion group (209.40 ± 91.15 MPa), silane group (184.13 ± 74.16 MPa), and control group (166.86 ± 72.22 MPa). A one-way ANOVA revealed a statistically significant difference between the groups (p = 0.034). Post-hoc analysis showed a significant difference only between the hydrofluoric acid and control groups. The failure patterns were predominantly mixed, with no significant association between the surface treatment and mode of failure (p = 0.509). Conclusion: Surface treatment enhanced the retention of glass fiber posts. Hydrofluoric acid and air abrasion improved the bond strength compared to untreated posts; however, hydrofluoric acid showed a significant advantage over the control group. Clinicians should consider both bonding efficacy and potential surface damage when selecting conditioning methods.