Effects of hybrid inorganic-organic nanofibers on the properties of enamel resin infiltrants - An in vitro study.

This in vitro study aimed to evaluate the overall mechanical properties of resin infiltrants doped with bioactive nanofibers and their ability in inhibiting enamel demineralization or achieving remineralization of the adjacent enamel to white spots. A commercial resin infiltrant (ICON, DMG) was doped with hybrid inorganic-organic nanofibers and analyzed for degree of conversion (DC, n = 3) and surface hardness (SH, n = 6). Subsequently, enamel specimens (6 × 4 × 2 mm) were prepared and submitted to a demineralizing/remineralizing process to produce a subsurface caries-like lesion. The specimens were treated with one of the following materials: ICON infiltrant, DMG (control); ICON + nanofibers of poly-lactic acid (PLA)-filled with silica (PLA-SiO); ICON + nanofibers of (PLA)-filled with calcium incorporated into a silica network (SiO-CaP). Then, the specimens were subjected to a pH-cycling demineralizing/remineralizing model for 7 days at 37 °C. The %ΔSH change (after treatment), %SH loss and %SH recovery (after pH-cycling regimen) were calculated after SH evaluation (n = 9/group). The Ca/P weight ratio before and after pH-cycling regimen was evaluated through SEM/EDX. The results of DC were analyzed through the T-test (p < 0.05). ANOVA followed by Tukey's test (p < 0.05) was performed for hardness and EDX. A significant SH increase was observed in the ICON/SiOCaP group (p < 0.05). The ICON/PLA-SiO presented higher DC values than the control group (p = 0.043). All groups presented significant difference in %ΔSH (p < 0.05), although the specimens treated with ICON/SiOCaP presented greater values. Regarding the %SHL and %SHR, the ICON/SiOCaP and ICON/PLA-SiO were significantly different compared to the control group (p < 0.001). However, no difference was observed between the ICON/SiOCaP and ICON/PLA-SiO The Ca/P ratio showed that the ICON/SiOCaP and ICON/PLA-SiO after the pH-cycling regimen differed from sound enamel and modified infiltrants before pH-cycling. In conclusion, tailored hybrid nanofibers may be incorporated into enamel resin infiltrants without compromise the mechanical properties of such experimental materials. These latter can inhibit the demineralization of enamel and increase its hardness during pH-clycling challange.