予防歯科におけるレーザー

う蝕予防を中心として

抄録

The effect of the laser beam on the tooth structure is principally due to an acquired resistance against acid decalcification of human enamel. We have demonstrated that, of 9 different kinds of laser, the normal pulse Nd: YAG laser is the most suitable for acquired resistance of human enamel. The glazed surface of the enamel was observed immediately after the laser irradiation with an energy density of 47J/cm2. The acid resistance of the lased enamel was observed even after etching in an acidic solution. This means that the surface structure of the enamel still persisted after the acid treatment. In treatment with laser irradiation and fluoride application combined, the enamel treated with an acidulated phophate fluoride (APF) after the laser irradiation obtained the most remarkable acid resistance compared with the other treatments. In this case, the inhibition of calcium dissolution from the enamel was more than 90% (Fig. 1). This level of inhibition has never been approached before. A possible mechanism of the acid resistance of enamel was proposed. In the clinic, sensory responce of 11 subjects during the laser irradiation is summarized (Table 1). Among the 11 subjects, 9 felt a warm sensation during the irradiation, one felt a transient pain, and one felt an impact sensation. The laser beam was also applied at the surface of incipient caries. The black paint almost completely disappeared after the laser irradiation. Then the lased enamel was treated with APF. No visible expansion of the lesion was observed for 24 months after the laser and fluoride application.