The Influence of Low Power Laser Local Irradiation on the Mineralization of Tooth Germ in Mice

To elucidate the in vivo effect of low power diode laser irradiation on mineralization in molar tooth germ, we examined the effect of the laser on the development of mandibular first and second molars in neonatal mouse. In a newborn mouse, the mandibular first molar showed differentiated odontoblast, differentiated ameloblast, slight dentin and enamel formation. The second molar was an early bell stage. In a two day-old neonatal mouse, the developmental stage of the second molar corresponded to the stage of the first molar in a newborn mouse. The laser (50mW, 5min/day) was irradiated to the mandibular tooth germ at twice and the chemical and histological changes in these molars were examined. In the second molar showing an early developmental stage (cell proliferation and differentiation), the laser irradiation increased alkaline phosphatase activity, calcium content and the formation of both dentin and enamel. Also, in the first molar showing a late developmental stage (additional mineralization), the laser irradiation also increased the mineralization in both dentin and enamel. From the in vivo experiment, we confirmed that diode laser irradiation accelerated tooth formation and mineralization at all developmental stages observed in the present study.(J. Jpn. Soc. Laser Dent. 7: 22-29, 1996 Reprint requests to Dr. Okumura)