The Nd YAG laser is useful in oral surgery because of its superior hemostatic and coagulating effects.
The purpose of this study is to examine the hemostatic effects of tongue wounds caused by the Nd: YAG laser and their healing process. The laser's effects on the capillary architecture and the healing process were observed using the India ink perfusion method and the injection replica scanning electron microscope method. Six-week-old male Wistar rats were used in this experiment. To study hemostatic effects, irradiation of 6, 12 and 18 watts was applied for 1.0 second, and the rats were sacrificed immediately. To study the healing process, irradiation of 6 and 12 watts was applied for 1.0 second, and the rats sacrificed on the 4th, 7th, 14th and 28th days after irradiation. The results were as follows.
The capillaries around the wound showed complete hemostasis by the Nd: YAG laser irradiation at 6, 12 and 18 watts.
Healing process of 6 watts: Epithelialization and direct proliferation of new capillaries from around the wound were observed on the 4th day. New capillaries showed continuity and capillary loops appeared at the wound margin on the 7th day. The regeneration of filiform papillae and the continued formation of capillary loops were observed on the 14th day. The wound was almost completely healed on the 28th day.
Healing process of 12 watts: Epithelialization was not observed, but the direct proliferation of new capillaries from around the wound was observed on the 4th day. Epithelialization was noted, but the capillary architecture was insufficient on the 7th day. The regeneration of filiform papillae and the formation of capillary loops were observed on the 14th day. Continued development was seen on the 28th day.
The regeneration of filiform papillae was observed as a conical elevation from the margin of the wound. The regeneration of capillay loops appeared as capillary protrusion on the 7th day after irradiation. The presence of capillary loops under the filiform papillae was necessary for the regeneration of the latter.
As to the difference between 6 and 12 watts, healing of the capillaries at 6 watts was observed earlier than at 12 watts in regard to epithelialization, the germination of new capillaries, and the stage of anastomosis. The wound almost completely healed at 6 watts, whereas healing was insufficient at 12 watts on the 28th day.