Niobium silicate as a filler for an experimental photopolymerizable luting agent.

PURPOSE: To synthesize niobium silicate particles (SiNb) and incorporate into resin-based luting agents. METHODS: SiNb particles were synthesized and characterized by x-ray diffraction, FTIR spectroscopy, particle size, and specific surface area. Luting agents were formulated with 50 wt% BisGMA, 30 wt% TEGDMA and 20 wt% UDMA. BAPO was used as a photoinitiator in 1mol%. The SiNb particles were incorporated into the agents at concentrations of 50 wt% (SiNb50%) or 65% wt% (SiNb65%). Barium glass particles at the same concentrations were used as controls (SiBa50% and SiBa65%). Refractive index, degree of conversion (DC), polymerization kinetics, softening in solvent, radiopacity, film thickness, color stability, flexural strength (FS) and micro shear bond strength (microSBS) were evaluated. RESULTS: SiNb particles were successfully synthesized with an adequate structure to be applied as inorganic fillers. SiNb groups had higher DC, lower %DeltaKHN, greater film thickness and greater radiopacity than the SiBa groups. Color stability was greater for SiNb50% and SiNb65% after six months of storage, as demonstrated by DeltaE00. DeltaWID values were lower for the SiBa groups. FS results decreased over time, and lower values were found for SiNb. In microSBS, the values of SiNb65% were higher at 24 h (45.22 MPa) and at six months (36.83 MPa), with statistically differences from values for the SiBa groups. CONCLUSIONS: SiNb particles were successfully synthesized using the sol-gel method, and their incorporation into luting agents at a concentration of up to 65% improved the physicomechanical characteristics and color stability of these agents.