An in vitro study to assess the efficacy of OH- ion superadded alkali-ion water in inhibiting caries and secondary caries

Ryoichiro Uchida, DDS,a Khairul Matin, BDS, PhD,a and Junji Tagami, DDS, PhDa,b

aCariology and Operative Dentistry, Department of Restorative Sciences, Graduate School of Medical and Dental Sciences, and bGlobal Center of Excellence (GCOE) Program; International Research Center for Molecular Science in Tooth and Bone Diseases, Tokyo Medical and Dental University, Tokyo, Japan

Purpose: This study assessed the caries and secondary caries prevention efficacy of OH- ion superadded alkali-ion water (AW) using an in vitro model.
Materials and Methods: Class 1 type cavities were prepared on bovine teeth blocks and they were immediately filled with Clearfil AP-X composite with application of an adhesive system. Biofilms were formed on the specimens using three species of cariogenic bacteria inside an oral biofilm reactor for 20 hours and specimens were further incubated separately for 7 days. During the incubation period the specimens were lightly rinsed with three pH levels of AW (AW-H: 11.5, AW-M: 10.5, and AW-L: 9.5) as the experimenting functional waters and control solutions (tap water; TW: 7.5 and heart infusion broth; HI: 7.3) dividing into five groups. The progression of the developed caries and secondary caries lesions were examined using a fluorescence microscope. Sizes of the lesions were measured by using an image analyzing software. Data were statistically analyzed by one-way ANOVA and Turkey’s HSD methods.
Results: The caries and secondary caries were visible mainly in enamel at the edge of resin restorations in all specimens. Photomicrographs and data on image analysis clearly showed that the lesion size was smaller in AW samples compared to control samples, which was statistically significant when compared between AW-H and TW (p<0.05).
Conclusion: It was suggested that AW can be used to inhibit the progression of caries and secondary caries by adjusting the pH levels as required.(Asian Pac J Dent 2011; 11: 1-8.)

Key Words: alkali-ion water, glucan, secondary caries, Streptococcus mutans