Application of Neutral Water to Dental Unit

Objectives: In order to minimize bacterial contamination of the water from dental units, we developed a new germ reducing system which uses so called neutral functional water. The objectives of this study were first, to evaluate the effect of the system on minimizing bacterial contamination of the dental unit water and second, to evaluate whether the neutral functional water causes corrosion or deterioration of the water lines of dental units.

Methods: A dental unit was equipped with a neutral functional water generator, which continuously mixed the diluted neutral functional water to the unit water. The water samples were collected from a syringe and an air turbine headpiece. As a control, dental unit tap water without addition of the neutral functional water was also collected. The dental unit was used at a typical dental office and both samples were collected sequentially for 7 days. In order to evaluate water contaminations, microbial counts and microbial species of the samples were measured. Corrosion and deterioration of water lines and connected equipments were evaluated by analyzing trace elements that had eluted into the samples.

Results: Heterotrophic bacteria were detected throughout the experiment period for the control, while the bacterial count in the samples from neutral functional water system fell to zero at 7 days after the start of the experiment. Regarding trace elements, total trihalomethane, dibromochloromethane, bromodichloromethane and bromoform demonstrated higher values for the neutral functional water system; however all of them were within normal range according to water quality criteria in Japan. There was no differences observed for other parameter.

Conclusion: A chair unit water supply system is considered to be extremely useful in preventing infection in the field of clinical dentistry with minimum corrosion of the water lines.