Infrared LED on Dental Pulp Cells Under Stress Conditions

Objectives: The aim of this study was to evaluate the effect of infrared LED irradiation on the metabolism and inflammatory modulation of cells from human exfoliated deciduous teeth submitted to LPS stimulation.
Methods: Three healthy deciduous teeth (n=3) were collected and seeded in 24-well plates with 10 µg/mL of LPS to induce inflammatory mediators formation. The cells were irradiated (850nm, 40mW/cm² and 80mW/cm²) at the proposed radiant exposures of 0 (control), 4 J/cm², 15 J/cm² and 30 J/cm² shortly after LPS application. Tests were performed 24h after irradiation for cell viability (MTT assay), number of viable cells (Trypan Blue), cell morphology (Scanning Electron Microscopy - SEM), quantification of Nitric Oxide (ON) and Reactive Oxygen Species (ROS). The data were analyzed using Kruskal-Wallis and Mann-Whitney (p<0.05).
Results: It was observed that irradiated groups showed larger number of viable cells than non-irradiated group with LPS (p<0,0001). All irradiation parameters were able to decrease ROS concentrations after LPS application compared to non-irradiated group (p<0,05). Concerning NO results, it was observed no difference among groups (p>0,05). SEM images showed cells with regular morphology and adhered to the substrate.
Conclusions: According to the parameters used in the study, the radiant exposure of 15 J/cm² and irradiance of 40 mW/cm² was the most effective irradiation parameter to stimulate and modulate oxidative stress in the pulp cells from primary teeth.