Microtensile bond strength and nanoleakage of self-etching adhesives containing different concentrations of 45S5 bioactive glass in caries-affected dentin

Objective To evaluate microtensile bond strength (μTBS) and nanoleakage (NL%) of self-etching adhesive systems containing different concentrations of bioactive particles when applied to caries-affected dentin: immediately and after 1 year of storage. Materials and methods Three experimental self-etching adhesive systems were developed: (1) Experimental control adhesive (without glass), (2) adhesive containing 5 % 45S5 glass (45S5 5 %), and (3) adhesive containing 20 % 45S5 glass (45S5 20 %). Sound human molars were used (n = 7). The dentin surface was exposed, and half of the specimens were subjected to artificial caries induction, followed by partial removal of the carious tissue. Adhesives were applied to the dentin surface, and teeth were restored with composite resin and sectioned. Specimens undertook microtensile bond strength tests in a universal testing machine (Instron 3342) at 24-h and 1-year. Interfaces of the sectioned specimens were observed under a stereomicroscope to obtain the fracture mode. For nanoleakage test, specimens were infiltrated with silver nitrate and the interface was analyzed using a Scanning Electron Microscope (SEM) at 24-h and 1-year. Data were subjected to ANOVA test (three-way) and Holm-Sidak post-hoc (α = 0.05). Results For μTBS (p = 0.574) and NL (p = 0.334) tests, there was no interaction between the 3 main factors (Material vs. Substrate vs. Time). There was an interaction between dentin and material for μTBS (p < 0.001) and NL (p = 0.005) tests. Bioactive adhesives with 5 % and 20 % concentration were not influenced by the type of dentin (p < 0.05). There was a reduction in μTBS values and an increase in NL values for the adhesive without bioactive glass in dentin affected by caries (p > 0.05). Conclusion Bioactive glasses had therapeutic action on dentin. The bond strength values of bioactive adhesives were maintained in caries-affected dentin and had low nanoleakage values. Clinical significance Self-etching adhesives containing 45S5 bioactive glass have the potential to preserve the dentin substrate and improve the longevity of restorations with composite resins.