Tooth-surface alteration with a prototype fluoride-containing tooth-surface treatment material

Objectives: This study was designed to examine the effects of a prototype fluoroaluminocalciumsilicate glass-containing tooth-surface treatment material (Nanoseal, Shimonoseki, Japan) on enamel and dentin. Methods: Human enamel and dentin plates were prepared and Nanoseal treatment (20 seconds of Nanoseal application followed by 24 hours of phosphate-buffered saline (Ca- and Mg-free, pH 7.2) immersion) was carried out for 1, 2 or 4 cycles. The specimens were then processed for surface morphological observation and Ca and Si incorporation depth measurement using a wavelength-dispersive X-ray spectroscopy electron probe microanalyzer with image observation function (SEM-EPMA). For the measurement of demineralization depths, specimens were similarly treated with Nanoseal, immersed in a 0.2 M acetic acid solution (pH4.5) for 24 h, and analyzed with a confocal laser scanning microscope. Results: The Nanoseal treatment caused the deposition of precipitates on the surface of enamel and dentin specimens. Occlusion of dentinal tubules with the precipitates was noted in dentin specimens. Moreover, incorporation of Ca and Si was detected in the superficial layer of the enamel and dentin, and the width of the Ca- and Si-rich layer showed an increase with increasing the treatment cycle. Furthermore, the Nanoseal treatment resulted in the decrease of demineralization depths on enamel and dentin surfaces. Conclusion: Nanoseal treatment of the enamel and dentin surfaces caused the deposition of precipitates, formation of Ca- and Si-rich layer, and increased the acid resistance.