Impact of silanization of different bioactive glasses in simplified adhesives on degree of conversion, dentin bonding and collagen remineralization

Objective: To analyze simplified adhesive containing pure or silanized bioglass 45S5 (with calcium) or Sr-45S5 (strontium-substituted) fillers applied on dentin and to evaluate the microtensile bond strength (mu TBS), interface nanoleakage, degree of conversion of ad-hesive, collagen degradation and remineralization.Methods: Ambar Universal adhesive (FGM) was doped with 10 wt% bioactive glasses to form following groups: Control (no bioglass), 45S5 (conventional bioglass 45S5), Sr-45S5 (Sr -substituted bioglass 45S5), Sil-45S5 (silanized bioglass 45S5) and Sil-Sr-45S5 (silanized bio-glass Sr-45S5). Adhesives were applied after dentin acid-etching using phosphoric acid at extracted human molars. Resin-dentin sticks were obtained and tested for mu TBS, nano -leakage at 24 h or 6 months. Degree of conversion was measured using micro-Raman spectroscopy. Dentin remineralization was assessed by FTIR after 6-month storage in PBS. Hydroxyproline (HYP) release was surveyed by UV-Vis spectroscopy. Statistical analysis was performed using ANOVA and Tukey's test (p < 0.05).Results: Regarding pTBS, Sr-45S5 and 45S5 presented higher and stable results (p > 0.05). Control (p = 0.018) and Sil-Sr-45S5 (p < 0.001) showed pTBS reduction after 6-month aging. Sil-Sr-45S5 showed higher HYP release than that obtained in the 45S5 group. Sil-45S5 showed mineral deposition and increase in pTBS (p = 0.028) after 6-months. All experi-mental adhesives exhibited higher degree of conversion compared to Control group, except for 45S5. All adhesives created gap-free interfaces, with very low silver impregnation, ex-cept for Sil-Sr-45S5.Significance: The incorporation of silanized 45S5 bioglass into the universal adhesive was advantageous in terms of dentin remineralization, bonding performance and adhesive polymerization. Conversely, Sil-Sr-45S5 compromised the pTBS, interface nanoleakage and had a negative impact on HYP outcomes.(c) 2023 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.

Automated summary

The objective of this study is to analyze the effects of simplified adhesives containing pure or silanized bioglass 45S5 or Sr-45S5 fillers on dentin. The results showed that the incorporation of silanized 45S5 bioglass into the adhesive improved dentin remineralization, bonding performance, and adhesive polymerization. However, the silanized Sr-45S5 compromised the bond strength, interface nanoleakage, and had a negative impact on HYP outcomes.