50 anterior teeth with flat interproximal root surface that had been extracted due to periodontal destruction were selected. All teeth were treated by the same procedure as conventional periodontal root treatment, such as scaling and root planing, root conditioning with tetracycline HCl(100mg/ml, 5min). The pre-treatment weight of each tooth was measured by a dial scale(SHIMADEU Co., LIBROR EB-220HU, capacity 220.000 g, Japan). All teeth were divided into 5 groups as follows; Nd:YAG laser irradiation(group 1, 1 W, 100 mJ, 10Hz, fiberoptic-root surface distance=5mm, 10 sec.×6times, EL.EN.EN060, Italy); NaF iontophoresis(group 2, 150µgA, 4 min.); Nd:YAG laser irradiation following NaF iontophoresis(group 3); NaF iontophoresis following Nd:YAG laser irradiation(group 4); No treatment(control group). Electric toothbrushing (Oral-B, Brown Co., Germany) was conducted during 1 hour(10 min.×6 times). Subsequently post-treatment weight was remeasured by the same method as pre-treatment weight measurement.

The difference of abrasion rate among all groups was statistically analyzed by ANOVA(SAS program).

Following results were obtained;

The results suggest that combined treatment of Nd:YAG laser irradiation and NaF iontophoresis on exposed root surface after periodontal therapy can enhance the abrasion-resistance of root surface and may inhibit the root caries development.