Effects of alkali-ion water on single species Streptococcus mutans biofilm

Mariko Gyo, DDS,(a) Ayako Okada, DDS, PhD,(a),(b) Masahiro Ono, DDS, PhD,(a) Junji Tagami, DDS, PhD,(a),(c),(d) and Khairul Matin, BDS, PhD(a),(d)

(a)Cariology and Operative Dentistry, Department of Restorative Sciences, Graduate School, Tokyo Medical and Dental University, (b)Department of Translational Research, School of Dental Medicine, Tsurumi University, Yokohama, (c)Global Center of Excellence Program; International Research Center for Molecular Science in Tooth and Bone Diseases, Tokyo Medical and Dental University, and (d)Support Program for Improving Graduate School Education, Tokyo Medical and Dental University, Tokyo, Japan

Purpose: The aim of this study was to assess the efficacy of alkali-ion water (AW) on removal of Streptococcus mutans (S. mutans) single species biofilms from bovine enamel surfaces in vitro.
Materials and Methods: AW solutions were produced by electrolyzing tap water using a water electrolyzing device. S. mutans biofilms were formed on bovine enamel blocks in an oral biofilm reactor for 8 hours and 12 hours, respectively. AW solutions, AW-H (pH 11.5) and AW-L (pH 10.5), were tested for their efficacy in dissolving water insoluble glucans (WIG) from the above biofilms. Sodium hydroxide solution (NaOH pH 13.5) and mineral water (MW pH 7.5) were also compared as controls. Biofilms were tried to disintegrate employing two different methods; 1) assisted by a driving force (shaking) which was a simulation of gargling by an adult, and 2) incubation without applying any driving force to observe biofilm disintegration effect on self-penetration by the solutions on their sole chemical potentiality.
Results: One-way ANOVA and Tukey’s HSD tests indicated that amount of dissolved glucan was significantly (p<0.05) more in AW-H compared to MW and AW-H yielded significant differences (p<0.05) in all tests with or without application of a driving force equivalent to NaOH. AW-L also dissolved more glucan than MW. Longer incubation period without any driving force dissolved more glucan by AW time dependently.
Conclusion: It was suggested that AW has the efficacy to remove a remarkable amount of biofilms by disintegrating glucans from the S. mutans artificial biofilms. (Int Chin J Dent 2009; 9: 55-60.)

Key Words: alkali-ion water, cariogenic biofilm, glucan, mutans streptococci, oral biofilm reactor.