The Effect of Coating Material Containing S-PRG Filler on the Prevention of Enamel Demineralization Detected by Optical Coherence Tomography

Purpose: We examined the effect of a fluoride-releasing coating material containing surface reaction-type prereacted glass-ionomer (S-PRG) filler on enamel demineralization using optical coherence tomography (OCT). Methods: Bovine incisors were cleaned and stored in physiological saline. The teeth were sliced, and enamel specimens were shaped into a rectangle (4×4×2 mm). Specimens (n=6) were treated with undersaturated 0.1 mol/l lactic acid buffer solution (pH 4.75) for 10 min, then placed in artificial saliva (pH 7.0; De Group). This treatment was repeated twice daily for 4 weeks, with specimens maintained in artificial saliva at 37°C between treatments. In the second group, a thin film of coating material was applied before demineralization (PRG Group). A third group (Control Group) was maintained in artificial saliva for 4 weeks. Using OCT at selected locations on the enamel surface, peak intensity (dB) and (μm) at 1/e2 were measured, and integrated values were calculated. All data were subjected to one-way repeated-measures analysis of variance and the Tukey-Kramer test with a significance level of 0.05. Results: The changes in integrated values differed between groups, there was a slight but significant increase in that of the Control Group (1,855-2,425), and a slight but significant decrease in that of the De Group (1,521-1,990). In the PRG Group, the integrated values doubled 7 days after the start of the experiment, followed by a further slight increase (1,560-3,666). Conclusion: Fluoride-releasing coating material containing S-PRG fillers prevents enamel demineralization detected by OCT.