An antibody or an antibody fragment that binds to an epitope under specifically chosen conditions; the binding of which to the epitope is broken under specifically chosen different conditions. Also, an antibody or antibody fragment with which a diagnostically, therapeutically or cosmetically active substance is optionally conjugated, for targeted and temporary diagnostic, therapeutic, or cosmetic treatment of externally accessible parts of the human and animal body. Both the specifically chosen binding conditions and the conditions wherein the binding is broken lie within physiologically acceptable limits and involve pH and/or ionic strength. The antibody or antibody fragment can be used for targeted and temporary treatment of externally accessible parts of the human and animal body. Also, a composition including at least one antibody, or a fragment thereof, according to the invention such as a teeth cleaning agent, mouthwash, mouth spray, chewing tablet, cream or ointment.