The effect of Sterilex UltraR for disinfection of dental unit waterlines

Aim: To evaluate the effect of a disinfectant agent based on hydrogen peroxide (Sterilex Ultra R, Sterilex Corporation, Maryland, USA) on the microbiological water quality in dental unit waterlines (DUWL). Setting: Six older dental units were disinfected with Sterilex Ultra R and another six units with sodium hypochlorite. The results were compared to six non-disinfected units examined during a period without patient treatment. Outcome measure: The number of colony forming units of bacteria (cfu)/ ml of water was determined according to European Standards on water quality. Design: The water quality was initially determined during a six week period, and subsequently in more detail for two weeks. Finally, the effect of prolonged administration of Sterilex Ultra(R) was investigated for six weeks. Results: Instillation of Sterilex Ultra(R) according to the recommendations of the manufacturer initially reduced the number of bacteria in DUWL to < 10(2) cfu/ml. However, following daily, as well as prolonged administration of Sterilex Ultra R a gradual recolonisation was observed resulting in bacterial numbers > 10(4) CfU/ml in a number of units. Major differences between the number of cfu/mI in individual units were observed. Conclusion: Neither daily nor extended administration of Sterilex Ultra R was capable of maintaining an acceptable water quality in these older dental units.