HEALING OF RAT MOUTH MUCOSA AFTER IRRADIATION WITH CO2, ND-YAG, AND CO2-ND-YAG COMBINATION LASERS

The healing process of wounds made by a combination laser was studied in 90 rats. The laser system enabled both separate and combined use of CO2 and Nd:YAG laser irradiations. The laser wounds and the control e xcision wounds made by alligator forceps appeared on both sides of the tongue. Specimens from the wound sites were taken immediately, 6 h, a nd 1, 2, 4, 7, 11, 21, 28, and 42 days after surgery. The wound-healin g process was studied by macroscopic evaluation before preparing the s pecimens for light microscopy. Some differences were noted in the woun d-healing process among the three groups into which the experimental a nimals were divided. Tissue coagulation damage was most extensive in t he Nd:YAG laser sites, where it was observed in its full extent 4 days after surgery. Epithelial cells were seen to begin to proliferate in all the wounds 6 h after surgery. Re-epithelialization was completed b y between 7 (CO2) and 21 days (Nd:YAG) at all the wound sites. The inf lammatory cell infiltration was more prominent in the Nd:YAG and the C O2-Nd:YAG combination laser wounds than in the CO2 and excision wounds during healing. Tissue regeneration occurred faster with less contrac tion in the combination CO2-Nd:YAG wounds than in Nd:YAG wounds. The b est macroscopic healing result was seen in the CO2 wound sites. The co mbination laser was effective both at cutting and at coagulating tissu e. Combining the CO2 and Nd:YAG laser irradiation into one beam result ed in a greater incision depth than what could have been expected from using the two lasers separately.