2001 Volume 51 Issue 1 Pages 29-36
We surveyed whether water used for dental treatment met the water quality standard and chlorine residue concentration rule stipulated in the Water Supply Law Enforcement Regulation in 20 dental clinics in Japan between Nov. 1999 and Jul. 2000. The water was collected at the shut-off valve and the tip of the air and water syringes in each clinic. Immediately after routine use at the end of the day or before the first treatment of the next day, the collected water was evaluated for chlorine residue concentration and the number of bacteria. The results of our tests showed that 45% of the water surveyed met regulation standards, but that, all the clinic had a chlorine residue concentration of less than 0.1 ppm, which is below regulation standards bacteria were found at the shut-off valves at the end of the day (n=5), but in all institutions bacteria was found in the tips of the air and water syringes (n=5). In the first water flow measured the next day (n=15), bacteria was found at the shut-off valves in 70% of clinics and at the tips of the air and water syringes in 77% of clinics. Although there have been several studies regarding the quality of dental treatment water, none of them discussed any fundamental counter-measures to address the issue of bacteria growth in the water piping system. In order to improve water quality, we devised a unique chlorine residue concentration compensator and evaluated its effectiveness in clinical use. The results were very successful : the water at all of the institutions surveyed met both the water quality standard and the chlorine residue concentration rule, and no bacteria were found.
