Anti biofilm effect of low concentration chlorine containing disinfectant assisted by multi enzyme detergent in dental unit waterlines.

The highly structured biofilms on the surface of internal tubing are regarded as the most important source of water pollution in the dental unit waterline (DUWL). Herein, the study aimed to evaluate the anti-biofilm effect of combined application of chlorine-containing disinfectant with multi-enzyme detergent in the dental unit waterline. Six dental units were included and randomly divided into two groups - Group A was treated with chlorine-containing disinfectant and multi-enzyme detergent; Group B was treated only with chlorine-containing disinfectant as control. All groups were treated once a day for four weeks. The anti-biofilm effect was evaluated by heterotrophic plate counts in output water, structure of biofilms, and fluorescence density of biofilms before and after treatment. Abundant opportunistic bacteria forming dense biofilms were observed before treatment. After one week, scanning electron microscopy showed the extracellular polymeric substance of biofilms in Group A was partially destroyed. The biofilms of Group A were completely removed in the third week, while the biofilms of Group B were still present. The combined application of chlorine-containing disinfectant and multi-enzyme detergent achieved a satisfactory effect on biofilms removal, demonstrating this strategy may play a significant role in reducing contamination in the dental clinic.