A histopathological study of the effects of low-power laser irradiation on wound healing of exposed dental pulp tissues in dogs, with special reference to lectins and collagens.

This study investigated the effects of low-power laser irradiation on exposed pulp tissue in dogs. Gallium-aluminium-arsenide diode laser (300 mW) irradiation was applied to the exposed surface of the pulp, and histopathological changes were observed at 1, 3, and 7 wk after the operation. In addition, the lectin (concanavalin A, Dolichos biflorus agglutinin, peanut agglutinin, Ricinus communis agglutinin I, soybean agglutinin, Ulex europeus agglutinin I, and wheat germ agglutinin) binding pattern and distribution of collagens (type I, III, and V) were examined to determine the histochemical and immunohistochemical nature of wound healing. The fibrous matrix formation and the continuing changes in the dentin bridge formation of the irradiation group were observed earlier (1 wk after the operation) than in the nonirradiation control group. Lectin histochemistry and collagen immunohistochemistry showed that concanavalin A, peanut agglutinin, wheat germ agglutinin, and collagens (types I, III, and V) were distributed in the fibrous matrix and dentin bridge. The expression of these lectins and collagens occurred earlier in the laser irradiation group than in the control group. These results suggest that laser irradiation accelerates wound healing of the pulp and the expression of the lectins and collagens. Furthermore, D-glucose-, D-mannose-, N-acetyl-D-galactosamine-, and N-acetyl-neuraminic acid-binding sugars and type I, III, and V collagens play an important role in the healing of pulp wounds.