Resin-dentin Interface Remineralization Effects on Bond Strength

Objectives: The purpose of this study was to evaluate the remineralization effect on the dentin bond strength promoted by treatment with a bioactive glass (Bioglass 45S5) and with a bioactive glass-ceramic (Biosilicate) developed in Brazil.
Methods: Thirty dentin discs (8x8x5mm) were divided into 3 groups (n=10): G1) control group; G2) Bioglass 45S5 remineralized group; G3) Biosilicate remineralized group. The specimens were etched with 37% phosphoric acid for 15s, followed by copious water rinse and gently air dried. Dentin hybridization was performed with a two step etch-and-rinse adhesive (Optibond S- Kerr, Orange, CA, USA) applied according to the manufacturer's instructions. Remineralization process of G2 and G3 was done after acid conditioning and before adhesive treatment. Bioactive material solutions were prepared by mixing 0,015mg of the specific agent powder in 1,35ml of distilled water. Remineralization treatments were carried out through the active application of the bioactive solution at conditioned dentin during 30s. After adhesive treatment, five 1-mm-thick increments of a resin composite were built up at dentin surface. These restored disks were stored in artificial saliva at 37°C during 24h, were sectioned into 0.8mm² beams and then were subjected to microtensile bond strength testing (μTBS). The fractured modes of specimens were observed with a scanning electron microscope (SEM). μTBS values were submitted to ANOVA and post-hoc Tukey-Kramer tests (p≤0.05).
Results: Significant high μTBS values were achieved in groups G2 (78,5 MPa + 15,2) and G3 (73,7 MPa + 14,8) when compared to G1 (58,9 MPa + 11,8) (p≤0.05). SEM analysis showed that failure modes were prevalently adhesive for both groups, G1 (35,7%), G2 (40%) and G3 (35,5%).
Conclusions: These results confirmed that remineralization treatment with Bioglass 45S5 and with Biosilicate increased dentin bond strength, indicating that mineral deposition within the hybrid layer improved the resin-dentin bond.