Accumulation of Ag in dentin and enamel of permanent teeth diseased by the secondary caries under processing of etching gel «Etchmaster Ag ™» is studied in this work. It is shown that the concentration of Ag in the hard tissues of the tooth is in the range 0.02-0.07 mg/g and it does not reduce the cohesive strength of the boundary between the seal and the hard tissues and dentin-enamel junction.