Durability of bactericidal activity in three electrolyzed water gels

Objectives:  Electrolyzed waters have been widely used in clinical dentistry because of their excellent bactericidal activities.  For the wider use, we developed three preparation methods of the neutral electrolyzed water gel (pH: about 7, residual chlorine concentration: 70-150ppm) which varied in the gelling agent.  In this study, bactericidal activity and chemical properties were examined about three neutral electrolyzed water gels which were prepared using each gelling agent, agar, carboxyvinyl polymer and xanthan gum, as compared with these gels in order to consider the applicability to sterilization in dental practice.   Methods: Three gels were prepared by our methods using each gelling agent.  After preparation, these gels were stored at room temperature or in a refrigerator.  Changes of these gels in the pH value and the residual chlorine concentration under each storage condition were examined.   Their sterilization effects were also examined just after each preparation and during storage.   Results: Just after preparation, all gel could completely sterilize the bacteria by 3-min treatment, and no significant difference in the bactericidal activity was shown among three gels. The gel containing xanthan gum showed a remarkable decline of the residual chlorine concentration.  Even the storage in the refrigerator did not show effective residual chlorine concentration two or three days later, and it was impossible to maintain the bactericidal effect.   On the other hand, it was difficult to maintain the sterilization effect by storage at room temperature in other gel containing agar or carboxyvinyl polymer, but it showed effective residual chlorine concentration and the excellent bactericidal effect during 21-day storage in the refrigerator.   Conclusions: It was suggested that it was inappropriate to use xanthan gum as a gelling agent, and agar and carboxyvinyl polymer were appropriate from the point of durability of the sterilization effect of gel by storage.