Since the laser was developed in 1960,its applying to optical communication and medical practice has been investigated well. There are many kinds of dental laser and more than twelve of them are used in Japan. High-energy lasers are useful in producing coagulation necrosis in target tissue with a subsequent reaction in the surrounding tissue. Various biostimulatory effects of low-energy laser irradiation have been reported that it acts on regeneration healing, fibroblast and chondral proliferation, collagen synthesis, nerve regeneration. It is used in odontotherapy for diseases of hard tissue and soft tissue, periodontitis and peri-implantitis. The usage rate of a dental laser is 30% of dental clinics in Japan and 60% of them use a laser with carbon dioxide gas. In this paper, we describe the carbon dioxide whether promote the wound healing or not. The laser is used for a lot of medical treatments now. Moreover, the laser is used for not only the treatment; its usage also has been increased for diagnosis and prevention of the disease. Especially, its research and development progress rapidly due to applying to the odontology for medical treatment.
