Aim of this study was to evaluate the quality of laser ablation in comparison with the classical drilling system. For the experiment the Er:YAG laser drilling machine was used. The system had a laser head, water cooler, and power supply with automatic control. Shape of cavity in comparison with classical drill, time of preparation and influence of cavity shape on filling materials retention were criteria for evaluation of non-contact Er:YAG ablation. The shape of cavity was irregular, the surface had a microretentive appearance. It was possible to remove enamel, dentin and the old adequate fillings, except for amalgam or metal alloys. Cavo surface margin discoloration ranging from 82 to 86 % could be a problem. From 4 to 8 % were observed changes of the color and anatomic form of the tooth. In comparison with classical treatment it could be said that the retention and quality of filling materials is the same or similar.

        Key words: dentistry – laser preparation – Er:YAG laser – enamel – dentin