Niobium containing bioactive glasses as remineralizing filler for adhesive resins

The aim of this study was to incorporate sol-gel-derived bioactive glass as filler into experimental adhesive resins and evaluate the influence of glass composition on the physicochemical and biological properties of the developed adhesives.

Sol-gel particles were produced with or without the addition of niobium (BAGNb or BAG, respectively). The produced particles were incorporated (2wt%) into experimental adhesive resins formulated with 66wt% bisphenol A-glycidyl methacrylate and 33wt% hydroxyethyl methacrylate. Ethyl dimethyl-4-aminobenzoate and camphorquinone were used as photoinitiator system. Two experimental groups were produced: A_BAGNb and A_BAG. The adhesive without particles was used as control (A_CG). The materials were tested for their degree of conversion, softening in solvent, and cytotoxicity. The mineral deposition was analyzed by Raman spectroscopy. Flexural strength and immediate and 1-year microtensile bond strength were evaluated.

No statistical difference was found in degree of conversion. A_BAGNb showed reduced softening and higher mineral deposition than A_CG and A_BAG after 28 days. A_BAG and A_BAGNb resulted in higher cell viability and lower flexural strength when compared to A_CG. After 1-year, A_BAGNb and A_BAG presented statistically significant lower μTBS values.

Sol-gel-derived bioactive glasses promoted increased mineral deposition and cell viability for experimental adhesives with increased phosphate content and longitudinal μTBS values for the A_BAGNb group. These results suggest the potential of the studied particles to be applied as bioactive fillers for dental adhesives. Reductions in longitudinal μTBS and flexural strength, however, were observed for both glasses compositions and must be considered.