A pilot study of 2 methods for control of dental unit biofilms

Objective: This pilot study was conducted to clinically evaluate 2 differen t concentrations of sodium hypochlorite for the control of dental unit biof ilms and to evaluate the efficacy of pasteurizing dental treatment water fo r patient care. Method and materials: Two dental units with no prior chemic al treatment were retrofitted with self-contained water systems for this st udy. One dental unit was treated with 5,000 ppm of sodium hypochlorite and the other with 1,500 ppm. Treatment consisted of a 10-minute contact with t he dental unit water lines, followed by a flush with a buffer solution. A p asteurizer was equipped with autoclavable spigots to provide dental treatme nt water. Heterotrophic Plate Count Samplers (Millipore) water sampler kits were used to quantify microbial contamination as absolute colony-forming u nits per millimeter. Scanning electron micrographs were taken of water line lumens to compare pretreatment and posttreatment biofilms. Results: Pasteu rized water was significantly less contaminated than was tap water. No sign ificant difference in contamination was found between the 5,000 ppm and 1,5 00 ppm treatment chairs, either in the reservoir water or effluent water. S canning electron micrographs demonstrated removal of the biofilms after sod ium hypochlorite treatments, regardless of the concentration used. Conclusi on: There was no significant difference between the abilities of 5,000- and 1,500-ppm concentrations of sodium hypochlorite to control contamination o f dental treatment water and biofilms, Pasteurization of tap water can redu ce contamination; this water can be used as acceptable dental treatment wat er (< 200 CFU/mL).