Can bioactive glasses compensate for polymer degradation in adhesive systems and reduce dentin permeability over time?

Objective To evaluate the dentin permeability of experimental adhesive systems incorporated with 45S5 and NbG bioactive glasses (10 % and 20 %), compared to an experimental adhesive without bioactive glass after 12 months of storage in PBS. Methods Two-step self-etching adhesiv systems containing 10 % and 20 % by weight of 45S5 and NbG bioactive glasses were tested on forty freshly extracted human teeth. An experimental adhesive without microparticles was used as a control group. Dentin permeability was evaluated immediately after adhesive system application, 30 days, and 12 months after storage in PBS. The formation of nanoprecipitates on the dentin surface and within the tubules was analyzed at the end of the permeability tests using SEM/EDS. For statistical analysis, data were subjected to Shapiro-Wilk tests, two-way repeated measures ANOVA ( Material x Time) and Holm-Sidak (α = 5 %). Results There was a statistically significant interaction between Material and Time (p < 0.001). Significant differences were observed in the reduction of dentin permeability values among the adhesive systems evaluated after 12 months of immersion in PBS (p < 0.001). All adhesive systems containing bioactive glass showed the lowest dentin permeability values compared to the control adhesive (p < 0.001). SEM images showed mineral precipitation on the surface of the samples and microparticles and precipitates at the entrance of the dentinal tubules in the bioactive adhesive groups. Conclusion The addition of 45S5 and NbG bioactive glass at concentrations of 10 % and 20 % to an experimental adhesive system decreased the dentin permeability of the specimens evaluated after 12 months of immersion in PBS compared to the same adhesive system without the addition of bioactive material.