The objectives of the present study were to evaluate the effects of soft laser irradiation for the proliferation and the differentiation of human bone cells and periodontal cells cultured on titanium plates and plastic dishes both derived from the identical donor.
Bone cells derived from mandibular fragments and periodontal ligament (PDL) cells from mandibular first premolars were obtained simultaneously from the identical orthognathic patient. Both cells in the 6th passage were seeded (5×103 cells/well) in 24-well plastic culture dishes with or without titanium plates and incubation continued for 72 hours. During the incubation period, soft laser irradiation was performed none, once, twice, which were served as control, 1×laser, 2×laser, respectively. At the end of incubation period, both cells were used for the assays of DNA synthesis and alkaline phosphatase (ALP) activity. The following results were obtained:
1. Bone cells cultured on plastic dishes did not show any significant change of DNA contents and ALP activity by the various time periods of soft laser irradiation. On the other hand, bone cells cultured on titanium plates showed significant increases of DNA contents and ALP activity by the soft laser irradiation, especially by 1×10 minutes laser irradiation group. In this group, the level of DNA contents and ALP activity by titanium-cultured-bone cells were significantly greater than those by plastic-cultured-bone cells.
2. In case of PDL cells, the level of DNA contents and ALP activity were constant for any kind of groups with the exception of 2×10 minutes laser group which showed significant DNA increase as compared to control group, suggesting that the existance of titanium plates and/or the irradiation of soft laser were not effective for cultured PDL cells.
These results suggest that the proliferation and the differentiation of bone cells cultured on titanium plates can be stimulated by the irradiation of soft laser in vitro.
