||Development of reliable new cures is expected in clinical dentistry, although there are still very few examples of the regenerative dentistry. In order to achieve breakthrough in these areas, new approache is proposed. Root canal therapy and filling methods using an optical irradiation lamp for composite resin polymerization. A transparent point for root canal restoration will be used and weak phototoxicity will facilitate apical tissue regeneration. Phototoxicity will also be used also for the medical treatment of root canal infection by optical irradiation only, without requiring extraction. And, crown removal and root filling points can be judged using light irradiation by observing the progress of symptoms.