This study was designed to determine the most effective concentration of fluoride and energy density of laser irradiation for the anticarious effect. For this study, surface hardness in enamel was measured before and after irradiation with pulsed Nd:YAG laser and the topical application of fluoride.
Of the permanent mandibular anterior bovine teeth, healthy, carious free ones were used. Three hundred specimens were made. Specimens within 25.45 Ijickers hardness numbers were assigned to 20 control and experimental groups each containing 15 specimens.
After forming artificial carious lesions, 1Q j/cm2, 20 J/cm2, and 30 J/cm2 eruegies were irradiated: on the enamel surface of each experimental group. Also NaF, NEW, Elmex gel(amine fluoride) and APF gel fluoride compounds were applied topically.
Next, all the specimens were placed into the pH circulatory procedures for eight days. Vickers hardness numbers were measured using a microhardness tester. Surface changes of the enamel were observed using an scanning electron microscope.
The comparative analysis yielded the following results
1. The reduction of surface hardness of the enamel surface was less in all groups with fluoride application than in the group without fluoride application.
2. The APF gel group with 10 J/cm irradiation showed the lowest reduction of surface hardness.
3. The reduction of surface hardness of the enamel surface in the group of laser irradiation without fluoride application
not showed any significant difference according to the energy density of the laser.
4. Under the scanning electron microscope, in enamel irradiated with 10 J/cm2 showed appearance similar to acid
etching surface. In enamel irradiated with 20 J/cm2, fine enamel crack was detected. In enamel irradiated with 30
J/cm2, severe enamel crack and fusion of enamel were detected.
These results suggest that one could obtain the best anticariogenic effects without damage to teeth in the group of application of APF gel after laser irradiation with 10 J/cm2.
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