Irradiation with blue light-emitting diode enhances osteogenic differentiation of stem cells from the apical papilla

This study aimed to evaluate the effects of low-energy blue LED irradiation on the osteogenic differentiation of stem cells from the apical papilla (SCAPs). SCAPs were derived from human tooth root tips and were irradiated with 0 (control group), 1 J/cm 2 , 2 J/cm 2 , 3 J/cm 2 , or 4 J/cm 2 blue light in osteogenic induction medium. Cell proliferation was analyzed using the 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) assay. Osteogenic differentiation activity was evaluated by monitoring alkaline phosphatase (ALP), alizarin red staining, and real-time polymerase chain reaction (RT-PCR). The results of the MTT assay indicated that SCAPs in the LED groups exhibited a lower proliferation rate than those in the control group, and there were statistically differences between the 2 J/cm 2 , 3 J/cm 2 , and 4 J/cm 2 groups and the control group ( P