|Budget Amount *help
¥2,400,000 (Direct Cost : ¥2,400,000)
Fiscal Year 2000 : ¥500,000 (Direct Cost : ¥500,000)
Fiscal Year 1999 : ¥600,000 (Direct Cost : ¥600,000)
Fiscal Year 1998 : ¥1,300,000 (Direct Cost : ¥1,300,000)
TCP slurry was extracted from tertiary calcium phosphate (TCP) of submicron particles, by which TCP sheets (dozens of μm in thickness) were made. The decalified enamel tip coated with slurry and sheets were irradiated by excimer laser, Q switch YAG laser and CO_2 Laser, respectively. We studied the effect of laser ablation on recalcification of enamel.
According to the conventional method, we made specimens as follows ; an extracted permanent tooth that approximately 200 μm of the surface was removed was polished, which was decalcified for 4 hours into a 0.1 M-lactic acid buffer solution (0.3 mM -HAp, pH 4.5). Two enamel specimen of the same tooth were employed. One specimen was irradiated on slurry or sheets (2 reacted groups), and the other one was then treated by single slurry and sheets without irradiation (control group). Some specimens were immersed with artificial saliva for 4 weeks, whose recalcification was observed. In making slurry, TCP (a mean granular diameter of 0.41 μm)
was prepared to 10-20% with purified water. In making sheets, 10% TCP slurry, agar powder and potato starch mixed with purified water was heated at 85℃, and dissolved. An adequate amount of the solution was then poured into a plastic schale (30-60 μm in thickness), was then left, dried and cut to approximately 5 mm square. As adhesive agents for TCP sheets, 5% CMC, a 0.3 mM-HAp solution and 75% HAp slurry were employed. Each condition of irradiation ; 248 nm (KrF) of excimer laser, 355 nm (the 3rd harmonic generation of basic wavelength 1,064 nm) of Q switch YAG laser and 10,600 nm of CO_2 laser at 2000 shots of 70-150 mJ/cm^2 and 0.8-1.0 W/lsec were irradiated.
Laser ablation occurred on slurry or sheets of enamel tip at 70-100 mJ/cm^2 of excimer laser/YAG laser and 0.8 W/lsec of CO_2 laser. The adherent effect of TCP in slurry or sheets for decalcified enamel surface was more strongly enhanced by laser ablation. In CO_2 laser irradiation, laser ablation plume was formed on slurry and sheets.
Recalcification of adherent slurry and sheets was also more advanced by artificial saliva. Less