Tooth decay and gum disease are caused by bacteria that settle in plaque. This bacterial plaque must be removed daily. You need the right cleaning technique and special tools for this. However, the deposits in the spaces between the teeth and under the gums are difficult to reach and therefore cannot be removed even with thorough brushing. Dental prophylaxis takes these problems into account. To come back to the question "what is prophylaxis": Prophylaxis means the complete removal of all dental plaque. Regular preventive appointments at the dentist complement brushing your teeth at home. Your dentist goes where your toothbrush can't.