Effect of AKBA on the biofilm formation (A) and preformed biofilm (B) by S. mutans ATCC 25175 and A. viscosus ATCC 15987. After incubation, the biofilms were stained with crystal violet and the optical density of stained biofilm was determined with a multidetection microplate reader at a wavelength of 595 nm (OD595). The results are expressed as average optical density readings for crystal violet assays compared to untreated control (without AKBA). The biofilm of S. mutans and A. viscosus were significantly inhibited (A) and reduced (B) when compared with untreated control (P < 0.05). Values are mean (± SD) from four independent determinations. *, P < 0.05 (Student's t test).