[The Helium-neon laser effect on skin and oral mucosal tissue]

The biological effects of the helium-neon (He-Ne) laser on skin and oral mucosa were examined for the first time electron microscopically. Canine epidermis, gingiva and sublingual regions were subjected to treatment by the helium-neon laser with varying exposure times. The exposed tissues were excised immediately after radiation and studied with an electron microscope. Depending on the exposure times, ultrastructural alterations were observed such as cytoplasmic vesiculation and vacuolization, mitochondrial changes, dilation of the endoplasmic reticulum, the Golgi cisternae and other endomembranes of the keratinocytes. Furthermore, ultrastructural changes were seen in stromal cells, endothelial cells of the blood and lymphatic vessels, nerves, muscle cells and in the extracellular compartment of the lamina propria. The ultrastructural alterations of different cell and tissue structures following helium-neon laser radiation were compared with the effects induced by other types of lasers. The results are discussed in light of the stimulation of biological cell processes by low-energy lasers.