Abstract
An index was established for the laser apparatuses selection for appropriate laser treatment in the clinic. In this experiment, rat skins were incised using CO2 and Nd:YAG lasers, and histopathological examination of each healing process was performed. After CO2 laser treatment, the margin showed coagulation necrosis with carbonization immediately after incision. A few days later, mild epithelial cell proliferation and inflammatory cell infiltration in subcutaneous tissue and dermis were observed. Thereafter, inflammatory changes diminished gradually, and granulation tissue, consisting of fibroblasts and neovascularization, was seen in subcutaneous tissue. Five and 6 days later, epithelial regeneration and necrosis tissue absorption had almost been completed, respectively. On the other hand, after Nd:YAG laser treatment, histological changes were similar to those after CO2 laser treatment. However, necrosis was greater than that after CO2 laser treatment, and inflammatory cell infiltration, chiefly neutrophils, were present in all specimens 0.5 days later. Although granulation tissue formation and necrosis absorption occurred, reepithelialization tended to be delayed in contrast to that after CO2 laser treatment. These findings suggested that the CO2 laser was more suitable to incise the skin or other tissues with the cornification stratified flattened epithelium than the Nd:YAG laser.
