Intraradicular Dentin Biomodification with Natural Agents for Bonding Glass-fiber Posts

Purpose: To evaluate the effects of pretreatment with different crosslinking agents on glass-fiber-post adhesive luting. Materials and Methods: Single-rooted human teeth (n = 20) were randomly assigned to four groups: proanthocyanidins (PA) from grape-seed extract, cardol and cardanol (separated from cashew nut-shell liquid) and negative control (hydroethanolic solution). The solutions were applied on 37% phosphoric acid-etched dentin for 60 s. Glass-fiber posts were cemented using a three-step etch-and-rinse adhesive (Scotchbond Multi-Purpose, 3M Oral Care) and composite cement (RelyX ARC, 3M Oral Care). Slices for the push-out bond strength test were cut and tested after 24-h or 6-month storage in distilled water. The dentin underlying the adhesive layer was analyzed by micro-Raman spectroscopy to evaluate vibrational formation of collagen crosslinks. Three additional slices per group were also made and the adhesive in-situ degree of conversion (DC) was analyzed by micro-Raman spectroscopy. The results were analyzed using two-way ANOVA and Tukey's test (p < 0.05). Results: No statistically significant changes in bond strength were found over time for any of the groups, except with cardol, which increased bond strength (8.4 +/- 3.9 MPa at 24 h to 15.0 +/- 2.9 MPa after 6 months, p < 0.001) after aging. The formation of peaks at 1117 cm(-1) and 1235 cm(-1) showed the presence of collagen crosslinks for all three biomodification agents. The DC outcomes showed no statistically significant differences between groups (p = 0.514). Conclusion: Biomodification agents did not impair adhesive polymerization. Cardol demonstrated a positive influence on intraradicular dentin bonding for glass-fiber-post luting.