Comparison of the Bond Strength of Silane-Treated Glass Fiber Posts at Different Solvent Evaporation Times: An In Vitro Study

Background Silane is used as a coupling agent on glass fiber posts to enhance chemical interaction at the post-resin cement interface. This in vitro study evaluated the bond strength of silane-treated glass fiber posts at different solvent evaporation times. Material and Methods This in vitro experimental study included forty single-rooted mandibular premolars assigned to four groups according to silane solvent evaporation time: G1 (control), G2 (60 s), G3 (120 s), and G4 (180 s). Specimens were stored in physiological saline at 37 °C. After endodontic treatment, root canals were prepared and glass fiber posts were cemented. In the experimental groups, silane was applied and allowed to evaporate for the allotted time. After cementation, the roots were sectioned into thirds (coronal, middle, and apical) and bond strength was determined using the push-out test on a universal testing machine. Welch's ANOVA with Games-Howell post hoc was used to compare groups. Statistical significance was set at p < 0.05. Results In the middle third, significant differences were observed between evaporation times (p < 0.001), with higher values for 180 s (13.94 ± 6.59 MPa) versus 60 s (3.86 ± 2.04 MPa; p = 0.004), 120 s (3.30 ± 1.85 MPa; p = 0.003) and control (4.69 ± 2.95 MPa; p = 0.007). In the coronal third (control: 7.09 ± 3.00 MPa; 60 s: 7.22 ± 3.16 MPa; 120 s: 4.81 ± 2.05 MPa; 180 s: 8.01 ± 4.34 MPa) and in the apical third (control: 6.49 ± 3.09 MPa; 60 s: 5.56 ± 1.96 MPa; 120 s: 5.19 ± 3.98 MPa; 180 s: 8.10 ± 3.40 MPa) no significant differences were detected between protocols (p = 0.164 and p = 0.196, respectively). When comparing root thirds within each protocol, only the 60 s group showed differences, with higher bond strength in the coronal third than in the middle third (p = 0.032). Conclusions Evaporation of the silane solvent for 180 s improved the bond strength of the glass fiber posts in the middle root third, while no significant differences were detected in the coronal and apical thirds between the times evaluated. Within protocols, the 60 s group showed lower bond strength in the middle third than in the coronal third. Taken together, these findings suggest that prolonging evaporation to 180 s may be a useful operative adjustment to optimize bonding in the middle third, with no evidence of consistent benefit in the coronal and apical regions.