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Published on: January 12, 2017
Carbon dioxide laser irradiation stimulates mineralization in rat dental pulp cells
Y Yasuda1, E Ohtomo, T Tsukuba
1Division of Clinical Cariology and Endodontology, Department of Oral Rehabilitation, School of Dentistry, Health Sciences University of Hokkaido, Hokkaido 061-0293, Japan. yasuda@hoku-iryo-u.ac.jp
Aim:
To examine the effect of carbon dioxide laser irradiation on mineralization in dental pulp cells.
Methodology:
Rat dental pulp cells were irradiated with a carbon dioxide laser at 2 W output power for 20, 40 and 60 s, and were cultured in ascorbic acid and beta-glycerophosphate containing media. Cell viability was examined 24 h after laser irradiation by a modified MTT assay. Alizarin Red S staining was performed 10 days after laser irradiation. The amounts of secreted collagen from the cells after irradiation were quantified following Sirius Red staining. The expression levels of collagen type I and HSP47, collagen-binding stress protein, were analysed by real-time PCR. HSP47 protein expression was examined by Western blotting. Statistical analysis was performed using one-way analysis of variance (anova) followed by the Tukey's multiple comparison test.
Results:
The cell viability was not affected by laser irradiation at 2 W for up to 40 s. However, it was significantly decreased by 20% at 60 s (P < 0.05). The amount of mineralization after 10 days of irradiation at 2 W for 40 s was significantly increased in comparison to the other conditions (P < 0.05). The extracellular collagen production was significantly increased by 73% on day 2 and 38% on day 4 after laser irradiation (P < 0.05). Although collagen type I gene expression was not changed by laser irradiation, HSP47 gene and protein expression was induced within 12 and 24 h, respectively.
Conclusions:
These results suggested that carbon dioxide laser irradiation stimulated mineralization in dental pulp cells. The laser irradiation also increased HSP47 expression but not collagen gene expression.
