Effect of a Prototype Fluoride-containing Tooth Surface Coating Material on Enamel and Dentin Surfaces

Abstract

The present study investigated the effect of a prototype fluoro-alumino-calcium-silicate glass-containing tooth-coating material (Nanoseal, Nihon Shika Yakuhin) on the ultrastructure, acid resistance, and elemental distribution of enamel and dentin surfaces in vitro. Labial enamel and dentin surfaces of extracted human incisors were used as test surfaces. Each specimen was twice coated with Nanoseal for 10 seconds, followed by being stored in phosphate buffered saline (pH 7.2) at 37℃ for 24 hours. For surface morphological observation, the specimens were coated, by using nail enamel, with Nanoseal covering half of the test surface. The specimens were then washed in acetone to remove the nail enamel, and demineralized in an acetic acid buffer (pH 4.5) for 24 hours. The surface ultrastructure was then analyzed by using a wavelength-dispersive X-ray spectroscopy electron probe microanalyzer with an image observation function (SEM-EPMA). For cross-sectional morphological observation and elemental distribution analysis, specimens were coated with Nanoseal, cross-sectioned, and analyzed with the SEM-EPMA. The surface analysis demonstrated that Nanoseal-coated surfaces show a deposition of nanoparticles, whereas uncoated surfaces show typical features of demineralization. The cross-sectional analysis revealed the formation of a nanoparticle-deposited layer, 1-2μm in thickness, on the enamel and dentin surfaces; and occlusion of dentinal tubules with nanoparticles in the dentin specimens. Moreover, incorporation of F and Si was detected in the superficial layer of the enamel and dentin specimens. In conclusion, the Nanoseal coating on the enamel and dentin surfaces resulted in a deposition of nanoparticles, the incorporation of F and Si into the coated surfaces and a resistance to acetic acid demineralization, which suggests that Nanoseal possesses anti-cariogenic and dentin desensitizing effects.