Formation of hydroxyapatite nanoprecursors by the addition of bioactive particles in resin-modified glass ionomer cements

Abstract Objective The objective of this study was to evaluate the impact of adding bioactive glasses 45S5 and niobophosphate (NbG) in different concentrations (5, 10 and 20%) of two resin modified glass ionomer cements (RMGIC). Materials and methods Two RMGIC were used: Vitro Fil LC (DFL) and Resiglass F (Biodinâmica) they were modified by the addition of two bioactive glasses - 45S5 or NbG. Different concentrations of bioactive glasses (5, 10 and 20 wt%) were mixed with the powder of the RMGICs. The properties evaluated were: alkalinization activity (pH), fluoride (F−), calcium (Ca2+) and phosphate (PO43−) release, flexural strength, flexural modulus, Knoop microhardness and bioactivity. The analyses of the surfaces were examined using SEM and FTIR after storage at 37 °C for 28 days in simulated body fluid (SBF). The data were analyzed using ANOVA One-way ( multiple comparison vs control ) and Holm-Sidak test (α = 0.05). Results The addition of 45S5 increased the pH while the addition of NbG neutralized the pH of the Vitro Fil RMGIC. The RMGIC Resiglass maintained its acidic pH condition in almost all conditions. The addition of the 45S5 and NbG in high concentration increased the release of F−, Ca2+ and PO43− ions. Resiglass did not reduce its mechanical properties with the addition of bioactive glasses (p > 0.05). NbG glass did not alter the mechanical properties of the Vitro Fil (p > 0.05). The addition of the bioactive glasses 45S5 and NbG contributed to the formation of nanoprecursors of hydroxyapatite. Conclusion The obtaining of bioactive RMGIC is dependent on the composition of the material. The NbG glass provides a neutralization of the pH, an increase of the ions release and the amount of precipitates without jeopardizing the mechanical properties of the RMGIC.