Application of D-Amino Acids as Biofilm Dispersing Agent in Dental Unit Waterlines

AIM AND PURPOSE: Biofilms in dental unit waterlines (DUWLs) are extremely difficult to eliminate. Aim of this study is to evaluate the efficacy of a mixture of four D-amino acids on biofilm dispersion in DUWLs. MATERIALS AND METHODS: A mixture of four D-amino acids (D-methionine, D-tryptophan, D-leucine, and D-tyrosine, 10 mM each), distilled water (control), and 0.1 M hydrochloric acid (HCl) was used in the experiment. In laboratory, pieces of DUWLs covered with biofilms were submerged in different solutions for 5 days, flushed, and measured OD(600) of the dispersed biofilms. Remnants of biofilms on the DUWLs were evaluated by SEM. In clinic, fifteen DCUs were incubated with test and control solutions, flushed, and measured OD(600) of the dispersed biofilms. Microbial count of DUWL output water was enumerated twice a week for four weeks. RESULTS: There was a slight, but not significant, increase in OD(600) of flushing water in D-amino acids group. D-amino acids effectively reduced bacterial plaque as demonstrated by SEM. Incubation with D-amino acids significantly reduced biofilms especially after the first day of flushing. Bacterial count in DUWL output water was significantly reduced after treatment with D-amino acids. CONCLUSION: D-amino acids are applicable as biofilm dispersing agents in DUWLs.