A method and composition is disclosed for treating oral diseases, including inflammatory periodontal disease, by utilizing photosensitizing compounds in long term effect or timed release formulations, including local highly concentrated formulations in biofilms on teeth and implants and oral wounds as well as periodontal pockets, and activating the photosensitizers with radiation to selectively destroy bacteria and other microbial bodies. Photosensitizers in a timed release formulation are released over a prolonged period of time. In a version, photosensitizers are housed within nanoparticles, and can be gradually released through biodegradation or periodically released by such processes as brushing, irradiation, ultrasonic and chemically induced release. The formulation is applied to the oral cavity and allowed to settle on biofilms therein, in periodontal pockets formed by disease, or coated at the desired sites. Released photosensitizers are activated by radiation of preselected wavelengths in one or repeated treatments which can be carried out either by a dental professional or as a repeated treatment by the patient at home. Alternatively, the photosensitizer molecule is also modified to more effectively target the molecule to the unwanted oral bacterial species. A further benefit is that the nanoparticles act to protect photosensitizers from inactivation or degradation by saliva or other body fluids.
