Potency of ozonated alkali-ion water in inactivating cariogenic bacteria

Ayako Okada, DDS,(a) Toru Nikaido, DDS, PhD,(a) Mariko Gyo, DDS,(a) Kanako Shida, DDS,(a) Junji Tagami, DDS, PhD,(a,b) and Khairul Matin, BDS, PhD,(a,b)

(a)Cariology and Operative Dentistry, Department of Restorative Sciences, and (b)Center of Excellence Program for Frontier Research on Molecular Destruction and Reconstruction of Tooth and Bone,
Graduate School, Tokyo Medical and Dental University, Tokyo, Japan

Purpose: This study assessed the effects of ozonated alkali-ion water (AW-OZ) on the caries inducing bacteria Streptococcus sobrinus (S. sobrinus), Lactobacillus casei (L. casei), and Actinomyces naeslundii (A. naeslundii) in their planktonic states.
Materials and Methods: Pellets of the above bacteria were prepared from fresh cultures and resuspended. Tokyo Metropolitan City tap water (TW) was used as the source of all experimental solutions and alkali-ion water (AW) was obtained by electrolyzing TW. An ozone delivery device was used to produce ozonated TW (TW-OZ) and AW-OZ. Phosphate buffered saline (PBS) and 0.05% sodium hypochlorite (NaOCl) were included as controls. The bacterial pellets were then inoculated with the solutions and stored at room temperature for 30 minutes. Viability of the bacteria was subsequently measured.
Results: Examining viability following staining with a BacLight viability kit, it was observed that all three species of cariogenic bacteria died in significantly larger numbers with TW-OZ and AW-OZ treatment compared to PBS, TW or AW. For S. sobrinus and L. casei, the above data were confirmed by viability counting and was also verified by turbidimetric analysis for A. naeslundii. However, sparging ozone inevitably reduces the pH levels of the solutions and that this reduction is very significant for TW-OZ. However, in AW-OZ, the pH could be maintained with low alkali levels (8.40).Conclusion: Both TW-OZ and AW-OZ had an antibacterial effect on the three cariogenic biofilm forming bacteria and AW-OZ might be considered as the safer for human usage.
(Int Chin J Dent 2007; 7: 79-85.)

Key Words: cariogenic bacteria, ozone, ozonated alkali-ion water.