2017 Volume 60 Issue 6 Pages 273-281
Purpose: Several desensitizers that are routinely used in clinical situations for dentin hypersensitivity are also expected to have a demineralization inhibition effect. Because of the increasing incidence of root caries in an aging society, it is crucial to establish preventative and restorative procedures. The purpose of this study was to evaluate the effectiveness of sealing materials for demineralization inhibition and increasing fluorine uptake by the acid-treated root surface of the human tooth, through the use of automatic pH cycling.
Methods: Seven extracted human molars were used in the study. One of the teeth was divided into four specimens and demineralized in a buffer solution (0.2 mol/l lactic acid, 3.0 mmol/l CaCl2, 1.8 mmol/l KH2PO4, 2% carboxymethyl cellulose, pH 4.5) at 37°C for 72 hours. Three different fluoride-containing materials, namely “MS Coats F” (MS), “MS coat HyS Block gel” (HS), and CTX2 Varnish (FV), were used in this study. Each material was applied to the original root surface, which was then stored in a phosphate-buffered saline (PBS) solution (pH 7.5) at 37°C for 24 hours. Single sections, 300 μm thick, were obtained from each specimen. Untreated specimens were used as controls. The fluorine and calcium distributions in the carious lesion in each specimen were evaluated using the proton-induced gamma emission (PIGE) and proton-induced X-ray (PIXE) techniques, respectively. All surfaces of the specimen, except the outer surface, were covered with wax, and the automatic pH-cycling system simulated daily acid changes (pH 7.0-4.5) occurring in the oral cavity for 2 weeks. Caries progression was analyzed using transverse microradiography (TMR), taken before and after the pH cycling. The increment of integrated mineral loss (ΔIML) after the pH cycling was calculated from the TMR images and analyzed using the Games-Hawel test (p<0.05).
Results: In-air μPIXE/PIGE analysis demonstrated that all sample groups showed increased uptake of fluorine in the root surface compared with the controls. However, only the HS group showed significantly higher fluoride uptake. TMR analysis found that both HS and FV showed significantly lower values of ΔIML than the control group. There were no significant differences between the control and MS groups.
Conclusion: All three samples demonstrated a tendency towards increased uptake of fluoride from fluoride-containing hypersensitivity desensitizers and a demineralization inhibition effect on root dentin. These results suggest that fluoride-containing hypersensitivity desensitizers can be used for the prevention of root caries.
