An interchangeable brush head with ultrasound action makes it possible by way of the thin wall, which has a wall thickness of equal to or less than a millimeter and a low damping coefficient, for the energy to be transmitted as directly as possible by the ultrasonic waves into the effective medium, whereby the otherwise very high losses in the case of such prior-art appliances of the type in question are largely avoided, wherein, at the same time, the safety-related and dental-care aspects and the user-friendliness are increased. Further advantageous measures for increasing the efficiency of transmission are also present. Certain embodiments have only a directly interchangeable insert with the bristles thereon, this being environmentally friendly, user-friendly and cost-saving. In other embodiments, the entire interchangeable brush head, together with the electromechanical transducer installed therein and the neck, has to be replaced.