Introduction: The authors review the present state of the problems in connecting composite materials to hard dental tissues. Objective: The aim of the work was to examine and compare the appearance of enamel after adhesive adjustment (adaptation) by a total etching technique after treatment with an acid primer of the self-etching adhesive. Material and Methods: The experiment was made with 30 premolars extracted for orthodontic reasons. The extracted teeth were divided into groups, five premolars each. The etching gel of orthophosphoric acid was used for enamel without grinding as well as for enamel freed of the most superficial layer by grinding. After rinsing and drying the enamel prepared in this way was observed by electron microscope. In order to examine the adhesive preparation of dentine, grinding for denuding the dentin and formation of smear layer was made in 10 samples. The dentin prepared in this way was treated in five samples with orthophosphoric acid and by an acid primer in five other samples. The results were examined by electron microscope. Results: It has become obvious that the enamel treated with orthophosphoric acid displayed a jaggier surface of better quality for mechanical adhesion than the enamel treated with a self-etching primer. In the morphology of dentine surface there was no difference between the two ways of treatment. Conclusion: The self-etching adhesives are substantiated in cases, where more extensive atreas of dentine are available. They represent a lower risk of tightness in joining the filling.

        Key words: adhesion – adhesive – primer – self etching adhesive