Abstract
A forecast of demineralization and remineralization on teeth in the oral cavity is important to prevent and treatment of the occurrence and progression of caries. The automatic pH-cycling system developed by Mastuda et al. can simulate daily changes in pH that occur in the oral cavity. In the previous study, permanent teeth were used to evaluate the caries progression and inhibition. However,there was no study that used deciduous teeth. Therefore, the aim of this study was to compare and evaluate the demineralization on deciduous and permanent tooth enamel using the automatic pHcycling system.A 150-μm thick single-section specimen was prepared from a human extracted deciduous molar and permanent third molar and polished surface was coated with Sticky Wax. The experimented condition was 9 pH cycles/day for four weeks, and a demineralizing solution (lactic acid solution, pH 4.5) and remineralizing solution (HEPES solution, pH 7.0) were used to reproduce the same pH changes that typically occur in the oral cavity. During the interval, the specimen was left in the remineralization solution. The Transverse Microradiography(TMR) images of each specimen were examined to evaluate the progression of artificial caries with respect to integrated mineral loss(IML) and lesion depth(Ld) at week 1, week 2, week 3 and week 4.Integrated mineral loss of the deciduous teeth was significantly higher than that of the permanent teeth at all weeks. Lesion depth of the deciduous teeth was significantly higher than that of the permanent teeth at all weeks. Especially, integrated mineral loss and lesion depth of the deciduous tooth at week 4 was higher than that at other weeks.The results suggested that the occurrence and progression of demineralization of the deciduous tooth is higher than the permanent tooth, and we concluded that the automatic pH-cycling system was qualified as a system that evaluated demineralization of the deciduous tooth and the permanent tooth. It could be beneficially employed to clarify the difference of the deciduous tooth and the permanent toothinoralcavity.
