Niobium silicate as a filler for an experimental photopolymerizable luting agent

Abstract

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 (µSBS) were evaluated. Results: SiNb particles were successfully synthesized with an adequate structure to be applied as inorganic fillers. SiNb groups had higher DC, lower %ΔKHN, 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 ΔE00. ΔWID values were lower for the SiBa groups. FS results decreased over time, and lower values were found for SiNb. In µSBS, 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.

A Scoping Review on the Polymerization of Resin-Matrix Cements Used in Restorative Dentistry

“…Regarding the inorganic composition, commercially available resin-matrix cements contain an inorganic content ranging from 57 up to 78 wt% [ 13 , 14 , 19 , 55 , 56 , 57 , 58 , 59 , 60 ]. As shown in Table 1 , colloidal silica, ytterbium, or barium glass are the most frequent inorganic particles used as fillers [ 19 , 61 ]. However, other combinations of fillers have also been used, such as fluoroaluminoborosilicate glass, strontium calcium aluminosilicate glass, quartz, or other glass fillers [ 13 ].…”

“…However, other combinations of fillers have also been used, such as fluoroaluminoborosilicate glass, strontium calcium aluminosilicate glass, quartz, or other glass fillers [ 13 ]. The inorganic filler content is responsible for enhanced mechanical properties, although resin-matrix cements usually have a lower filler content when compared with resin-matrix composites [ 58 , 61 ]. Resin-matrix cements reveal a high variability in shape, size, and content of inorganic filler particles [ 56 ].…”

Orthodontic resins loaded with niobium silicate particles: Impact of filler concentration on the physicochemical and biological properties

“…The increased particle concentration may impair light transmission, reducing the light available through the material 29 . As an amorphous structure is observed for the SiNb particles, the light scattering could likely be limited when compared to other bioactive inorganic particles used as filler for remineralization 17 . Most of the used bioactive particles are based on crystalline oxides 15,18,21,30 with high refractive index (RI 2–3) values that differ from the values obtained in methacrylate 31,32 .…”

“…Most of the used bioactive particles are based on crystalline oxides 15,18,21,30 with high refractive index (RI 2–3) values that differ from the values obtained in methacrylate 31,32 . Previous reports have shown that the SiNb particles presented RI values close to 1.5, similar to the base resin 17,18,28 . Inadequate polymerization is directly related to reduced performance with impaired resistance to degradation and mechanical properties, as well as potential cytotoxic effect 33,34 …”

“…15,16 The development of bioactive particles with tailored properties may overcome these limitations. Niobium silicates (SiNb) have been studied as fillers for dental resin composites, [17][18][19] showing adequate interaction with the polymeric matrix, maintaining the polymerization ability in the composites in combination with the capacity of modifying the environment promoting nucleation of minerals on its surface. This was possible through an adjusted synthesis for the production of a particle that combines high silica content, which is similar to the glassy particles currently used in commercially available orthodontic resin, 20 with niobium, a metal that has been studied for its ability to enhance mineral formation.…”