SDF acts to both prevent and arrest tooth decay in multiple ways: 1) it acts on the body of carious lesions by precipitating silver ion into the lesion, thus blocking diffusion pathways for cariogenic acids; 2) it interacts with dental enamel leading to the formation of fluoroapatite crystals making the tooth surface more acid resistant; and 3) the precipitated silver from SDF acts as a bactericidal agent disturbing the formation of cariogenic biofilm.