Topical application of concentrated sodium fluoride or stannous fluoride solution was practiced in the US some decades ago, but, because of safety concerns, this is no longer common (Chu et al., 2010). Application of silver fluoride or silver diamine
fluoride (SDF) solution at concentrations of 38 to 40% to arrest active cavitated caries lesions in primary teeth has been practiced in Australia and Japan for many years (Chu and Lo, 2008).