Mechanical and Chemical Changes in the Adhesive-Dentin Interface after Remineralization.

PURPOSE: To evaluate the remineralization effects of Bioglass 45S5 (BAG) on dentin composition, adhesive-dentin bond strength, as well as interface and diffusion zone thickness. MATERIALS AND METHODS: Dentin specimens were assigned to a control group (CG), in which the adhesive was applied following the manufacturer's instructions, and a remineralized group (RG), in which remineralization treatment was carried out by rubbing a remineralization solution (0.015 g of BAG with 1.35 ml of distilled water) on the etched dentin surface for 30 s before applying the adhesive. For bioactive analysis (n = 10), control and remineralized dentin were investigated using micro-Raman spectroscopy (mRS) and scanning electron microscopy (SEM). Stick specimens prepared with a three-step etch-and-rinse adhesive were submitted to a microtensile bond strength (µTBS) test (n = 10) after 24 h (24 h) and eight months (8 m). Micro-RS 3D-maps (n = 10) characterized the adhesive-dentin interface composition and diffusion zone thickness, and SEM images (n = 10) evaluated interface thickness. Data were analyzed using Student's t-test or two-way ANOVA and Tukey-Kramer's post-hoc test (α = 0.05). RESULTS: Remineralization treatment increased the mineral content of dentin. Mean µTBSs were statistically different at 24 h, with RG higher than CG; however, this difference was not significant at 8 m. When the adhesive was applied on remineralized dentin, its penetration was reduced, its physical interaction with phosphate was improved, and its degree of conversion increased. The diffusion zone in the CG did not differ from that of the RG, and interface thickness values of the CG did not differ from that of the RG. CONCLUSION: Remineralization treatment promoted mineral growth on the dentin surface, improved the interaction of dentin with adhesive monomers, and consequently resulted in higher immediate bond strengths.

The In Vitro Bioactivity, Degradation, and Cytotoxicity of Polymer-Derived Wollastonite-Diopside Glass-Ceramics.

Ca-Mg silicates are receiving a growing interest in the field of bioceramics. In a previous study, wollastonite-diopside (WD) glass-ceramics were successfully prepared by a new processing route, consisting of the heat treatment of a silicone resin embedding reactive oxide particles and a Ca/Mg-rich glass. The in vitro degradation, bioactivity, and cell response of these new WD glass-ceramics, fired at 900-1100 °C for 1 h, as a function of the Ca/Mg-rich glass content, are the aim of this investigation The results showed that WD glass-ceramics from formulations comprising different glass contents (70-100% at 900 °C, 30% at 1100 °C) exhibit the formation of an apatite-like layer on their surface after immersion in SBF for seven days, thus confirming their surface bioactivity. The XRD results showed that these samples crystallized, mainly forming wollastonite (CaSiO3) and diopside (CaMgSi2O6), but combeite (Na2Ca2Si3O9) crystalline phase was also detected. Besides in vitro bioactivity, cytotoxicity and osteoblast adhesion and proliferation tests were applied after all characterizations, and the formulation comprising 70% glass was demonstrated to be promising for further in vivo studies.