To explore the impact of exogenous dextranase (Dex) and sodium fluoride (NaF) on the biofilm formation of Actinomyces viscosus.

Crystal violet was used to quantify the biomass of Actinomyces viscosus treated with serial concentrations of Dex and NaF. Scanning electronic microscope was applied to detect the morphology and structure of the biofilms.

The formation of Actinomyces viscosus biofilm was inhibited when the concentrations of Dex or NaF rised. Compared with the separate use of 0.25 U/mL Dex and 40 or 80 μg/mL NaF, the combined use of these two agents could obviously inhibit the biofilm formation.

Both separate and combined use of Dex and NaF could inhibit the Actinomyces viscosus biofilm formation, and they displayed synergistic effect under certain conditions.