ABSTRACT
<p><b>OBJECTIVE</b>To observe the injury and repair of the subepithelial cordectomy by CO2 laser in different power.</p><p><b>METHODS</b>Thirty dogs were randomly divided into 5 groups according to different laser power such as A(1 W), B(3 W), C(5 W), D(8 W), E(cold instruments), 6 dogs in each group. Subepithelial cordectomy was performed on the dogs and the tissue damage and wound recovery were observed in different time after operation.</p><p><b>RESULTS</b>The mucosa reaction in group C, D was heavier than those in group A, B, E, and the wounds healed slowly with visible pathological scars. The densities of fibroblast and blood capillary were determined with optical microscope. It was found that those in group C, D were higher than those in group A, B, E. The difference was statistically significant (average P < 0.05). Observation by electron microscope showed that the injuries were lighter in group A, B, E and there was no significant difference in vocal cord repair process, while the injuries were more serious in group C, D with few elastic fibers in lamina propria and collagen fibers increased significantly after vocal cord repairing.</p><p><b>CONCLUSIONS</b>The tissue repair after subepithelial cordectomy by CO2 laser with low power (1 - 3 W) was similar to that by cold instrument surgery.</p>