Stimulatory effect of laser irradiation on calcified nodule formation in human dental pulp fibroblasts

The purpose of the present study was to investigate the effect of laser irr adiation on calcified nodule formation in human dental pulp (HDP) cells. HD P cells were irradiated once with a Ga-Al-As laser for 5 and 10 min, and ca lcified nodule formation was determined by von Kossa staining. The laser ir radiation increased the number of calcified nodules in a time-dependent man ner. The activity of alkaline phosphatase and production of collagen and os teocalcin in conditioned medium were measured. Both were higher in the irra diated group than in the nonirradiated group. These results suggested that formation of calcified nodules in HDP cells, as well as in alkaline phospha tase activity, the production of collagen and osteocalcin were enhanced by laser irradiation.