The analysis of the effect of etching of the carious cavity after preparation with a gel containing silver nanoparticles (Ag NPs) on the structure and strength properties of the "dentin- filling" and "enamel-filling" boundaries in permanent teeth with low caries resistance of hard tissues was carried out. The research samples were made from teeth removed for medical reasons in patients aged 18 to 60 years. The sealing was performed with adhesive systems of the IV and V generations, fluid and packable composites were selected as the filling material. Samples for metallographic studies were cut perpendicular to the main axis of the tooth, and their surfaces were polished mechanically and etched in concentrated orthophosphoric acid. The observations were carried out on light and scanning electron microscopes. It is shown that the etching gel does not lead to a decrease in the cohesive strength of the boundaries, despite the presence of silver there.
