Transdentinal photobiostimulation of stem cells from human exfoliated primary teeth

Aim To evaluate the effects of infrared light‐emitting diode ( LED ) irradiation on stem cells from human exfoliated deciduous teeth ( SHED s). Methodology Exfoliated primary teeth were obtained ( n  = 3), and SHED s obtained from the teeth were seeded on the pulpal surface of 0.2‐mm‐thick dentine discs produced from permanent molars. The cells were incubated for 24 h by placing the discs in plain Dulbecco's modified Eagle's medium ( DMEM ). The DMEM was then replaced with new culture medium formulated for odontoblast differentiation. After 12 h in the second medium, SHED s were irradiated through the dentine discs using an infrared LED (850 nm) with a power density of 80 mW cm −2 . Energy doses (EDs) delivered to the occlusal surface of the dentine discs were 0 (control), 2 and 4 J cm −2 ( n  = 6). Subsequent tests were performed 72 h after irradiation. These tests included cell viability ( MTT ), alkaline phosphatase activity ( ALP ), total protein production ( TP ), scanning electron microscopy ( SEM ), as well as gene expression for ALP , Col I, DSPP and DMP ‐1. Data were analysed using Kruskal–Wallis and Mann–Whitney t ‐tests (α = 0.05). Results Both EDs (2 and 4 J cm −2 ) significantly increased cell viability and ALP activity. For TP , ALP and Col I gene expression, only the 4 J cm −2 group had significantly higher values compared to the control group. Cell morphology was not affected by irradiation. Conclusion Infrared LED irradiation was capable of biostimulating SHED s through a 0.2 mm thickness of dentine, especially at the 4 J cm −2 level.