Phototherapy enhances dentin matrix protein production by dental pulp cells

Objective: In restorative dentistry, phototherapy applied on cavity floor may biostimulate subjacent pulp cells, improving local tissue healing. Therefore, the aim of this study was to evaluate the effects of infrared LED (850 nm) irradiation on dentin matrix proteins synthesis by cultured human dental pulp cells (HDPCs). Method: Near-exfoliation primary teeth were extracted (n=3), the pulp tissue was collected and a primary HDPCs culture was established. To evaluate the alkaline phosphatase (ALP) activity and total protein (TP) production, as well as collagen expression (Sircol Assay) and cell morphology (SEM), the HDPCs were seeded (3x10⁴ cells/cm²) using plain DMEM. After 24-h incubation, the DMEM was replaced by a new culture medium for odontoblast differentiation. After being maintained for additional 12 h in an incubator, the HDPCs were irradiated with an energy dose of: 0 (control), 2 or 4 J/cm² (n=12) and the evaluations were performed 72 h post–irradiation. Data were submitted to Kruskal-Wallis and Mann-Whitney tests (α=0.05). Result: Both energy doses (2 and 4 J/cm²) increased the ALP activity by 65% and 72%, and the collagen expression by 12% and 49%, respectively when compared to non-irradiated cells. TP was enhanced by 10% compared with the control group. HDPCs with normal morphology were observed for all groups. Conclusion: It was concluded that infrared LED irradiation was capable of biostimulating HDPCs to increase dentin matrix proteins synthesis. Overall, the best results were seen when 4 J/cm² were delivered to the cultured HDPCs.