"Metabolism of Odontoblast-like cells submitted to transdentinal irradiation with blue and red LED".

Objectives: The present study evaluated the trans-dentinal effect of light emitting diodes (LEDs) irradiation on the metabolism of odontoblast-like cells.

Methods: Seventy-two dentin discs (0.2mm thick) were obtained from human molar teeth. MDPC-23 cells (20,000 cells/disc) were seeded on the pulpal side of the discs using DMEM, supplemented with 10% fetal bovine serum (FBS). After 12h, the culture medium was replaced with DMEM containing 0.5% FBS. After additional 12h, blue (455±10nm) or red (630±10nm) LEDs were used at irradiances of 80 and 40mW/cm, respectively, to irradiate the occlusal side of the discs. The energy doses were fixed at 2 or 4J/cm. Cell viability, alkaline phosphatase activity (ALP), total protein production and collagen synthesis were evaluated 72h after irradiation. Data were submitted to Kruskal-Wallis and Mann-Whitney tests (α=0.05).

Results: Red light promoted proliferative effects at the energy dose of 4J/cm Conversely, cell cultures irradiated with 2J/cm emitted by the blue light showed reduced viability. ALP production was stimulated by red light in comparison with blue light at 4J/cm. Total protein production was reduced after exposure to blue light at 4J/cm, while no effect was observed on collagen production.

Conclusions: Irradiation with red LED at 4J/cm bio-stimulated the viability of odontoblast-like cells, whilst blue light had unfavorable effects on the cellular metabolism.