Biofilm Control - Ozonation in an Automated Waterline Cleaning Dental Unit

Objectives: To study the effects of water dissolved ozone as a sanitizer in an automated waterline cleaning dental unit to control microbial contamination. Methods: A Logos Jr. Dental Unit equipped with an Autosteril Self-Cleaning Dental Water System (Castellini S.p.A., Bologna, Italy)was retrofitted with a mature biofilm laden waterline. Baseline and 29 post flush heterotrophic plate counts for planktonic contamination with HPC water samplers (Millipore Inc.), and Laser Confocal Microscopy of the lumen to study presence/absence of biofilm was performed. BacLight® (Molecular Probes, OR,USA) was used to determine viability of biofilm/cells. 29 simulated between-patient cleaning cycles were performed utilizing 2ppm ozone in water generated by Aquia^TM Waterpick Technologies, Fort Collins CO, USA. Each automated cleaning cycle lasted 5 minutes. Water/irrigant used for simulation of patient care and post-sanitization waterline flush was water sanitized by ozonation using Aquia^TM. Results: Baseline waterline samples showed viable mature biofilm. Post study waterline samples showed no viable or non-viable biofilm. Heterotropic plate counts of effluent water at baseline was >2000 cfu/mL while the mean counts of the remaining 29 samples showed <10 cfu/mL (SD=6.2). Conclusions: Simulated between patient sanitization by ozonation of tap water generating about 2ppm of dissolved ozone was beneficial in controlling biofilms when used with the Autosteril of the Logos Jr. Dental Unit. Heterotrophic plate counts were also within the ADA's goal of <200 cfu/mL and CDC recommendation of <500 cfu/mL. Support in part from Diagnostic Science, BCD TAMUS HSC Dallas, TX USA; materials in part from Lynntech Inc., College Station, TX, USA and Castellini S.p.A., Bologna, Italy.