Effect of low-level laser on proliferation, angiogenic and dentinogenic differentiation of human dental pulp stem cells.

Background: The aim was to evaluate the effect of single and double doses of low-level laser irradiation on proliferation of human dental pulp stem cells (DPSC) and expression of vascular endothelial growth factor (VEGF) and dentine sialoprotein (DSP).

Methods: In this experimental in vitro study, after confirming the stemness of DPSCs, the cells were cultured in Dulbecco's Modified Eagle Medium (DMEM) for MTT assay and VEGF-ELISA and osteogenic medium for DSP-ELISA. The wells containing DPSCs were divided into three main groups and 9 subgroups (n = 7). In groups with single low-level laser, 660-nm diode laser was irradiated at 100 mW and 3 J/cm² energy density for 15 s. In groups with double doses of low-level laser the second identical irradiation was after 48 h. The MTT-assay and ELISA for DSP/VEGF (dentinogenic/angiogenic differentiation) were performed at 1, 7 and 14 days post irradiation. Using the SPSS software 20 (SPSS, Chicago, Ill, USA) with 95% confidence interval (P = 0.05), a two-way ANOVA test with Tukey's post hoc test was used for the effect of LLLI on VEGF and DSP. The One-Way ANOVA was used for of cell proliferation.

Results: Higher proliferation rate in both single and double low-level laser was reported. The difference was statistically significant for double doses of low-level laser (P = 0.001, P = 0.020 and P = 0.000 for 1, 7 and 14 days, respectively). Also after one, 7 and 14 days, cells in significant increase in DSP (P > 0.05) and VEGF (P > 0.05) was observed that was significantly higher for double doses of low-level laser.

Conclusions: Low level laser enhanced the mitochondrial activity and proliferation of DPSCs. Increased production of DSP/VEGF indicates dentinogenic/angiogenic activity.

Clinical relevance: Low level laser increases the proliferation of DPSCs, elevates the production of VEGF (which means better angiogenesis in regenerative treatments) and increases the production of DSP (which means better dentinogenesis in vital pulp treatments).