電解水による歯科用器具の消毒とその腐食傾向

Abstract

The excellent bactericidal activity of the electrolyzed acid water has recently been noticed in dentistry. The authors previously demonstrated the validity of the strong acid water as a disinfectant for impression showing rapid and reliable sterilization effect. In the present study, the applicability of the electrolyzed water to sterilization of dental metallic instruments was examined. The contamination bacteria tested were Streptococcus salivarius (IFO 13956). As the problem with the acid water is that it is potentially corrosive to metals, corrosion tests were also carried out. The instruments having simple configuration such as reamer and explorer could be sterilized by one-minute immersion in the strong acid water, while those of comlicated configuration such as diamond stones and burs required much longer time for equivalent sterilization. When the ultrasonic cleaning action was added in the strong acid water, all the instruments were sufficiently sterilized by one-minute treatment although such a cleaning itself could give little effect of removing bacteria from the instruments even by 20-minute treatment in distilled water. Another type of electrolized water, the week acid water 5.2 in pH showed almost the same effects as the strong acid water. The reamer and diamond stone showed no corrosion in 24-hour immersion in the acid water. The working end of the explorer was also sound while many corrosion pits were observed on its handle. A marked corrosion was found on the overall surface of the steel burs, and a localized loss occurred at the brazed area between the blade and shank of the carbide burs without the blade being harmed. It was confirmed that the week acid water was less corrosive than the strong. Significant damages of the burs by corrosion appeared after 3-hour immersion in the acid water. The term corresponds to 180-time repetitions of one-minute immersion treatment, indicating that such a corrosion behavior may not result in any practically serious problem because it may far exceed the mechanical lives in service of their blades. These findings suggest that both the electrolyzed strong and week acid waters may well be available as the disinfectant for dental instruments.