Abstract: Tooth enamel is treated with a dental etching acid to leach out the positvely charged calcium ions therefrom and to provide a roughened, porous, sponge-like appearing surface which is negatively charged. Said surface is treated with the positively charged ions of the heavy metals which are ionically attracted to said negatively charged surface and deposited into and on said sufrace which is remineralized with said heavy metal ions to form a relatively smooth surface like that of the original tooth enamel before the acid etch. Thereafter, the heavy metal covering said surface is converted into the corresponding heavy metal sulphide which is resistant to decay and to caries producing acids.