Avaliação transdentinária dos efeitos da fototerapia com LED infravermelho em células pulpares humanas: estudo in vitro

Abstract

The preservation of pulp tissue through conservative procedures has gained increasing relevance, especially in Pediatric Dentistry. Additionally, the use of phototherapy for pulp tissue repair—either by assisting in inflammation control or stimulating mineralized tissue formation—has emerged as a promising adjunctive treatment. This study investigated the effect of infrared LED phototherapy on the production of free radicals by human dental pulp cells seeded under a dentin barrier. The cells (150,000/well) were seeded onto dentin discs (0.4 mm thick) coupled to metallic devices (CPA – artificial pulp chamber) placed in 24-well plates. After 24 hours, TNF-α (25 ng/mL) was applied to induce an inflammatory environment, followed by a single irradiation at 850 nm using infrared LED at doses of 4 and 15 J/cm² (80 mW/cm²) in the respective groups. The experimental groups were: 4J without TNF-α, 4J with TNF-α, 15J without TNF-α, 15J with TNF-α, without TNF-α, and unstimulated control (the last two not irradiated). After 24 hours of irradiation, mitochondrial activity (MTT assay), cell morphology (scanning electron microscopy), and quantification of nitric oxide (NO) and reactive oxygen species (ROS) were assessed. Data were analyzed using the Kruskal–Wallis test followed by Dunn’s post hoc test (p < 0.05). TNF-α stimulation significantly reduced cell viability (85.53%; p = 0.001) and increased ROS (301.83%) and NO (119.49%) production compared to the control group. Irradiation with 4 J/cm² preserved viability (100.82%) and significantly reduced ROS (233.63%) and NO (102.35%) levels (p < 0.05). The 15 J/cm² dose maintained viability and NO levels similar to the control but did not significantly reduce ROS levels. Infrared LED photobiomodulation at 4 J/cm² was effective in modulating TNF-α-induced inflammation, maintaining cell viability, and promoting adhesion and proliferation of human dental pulp cells. These results suggest that, even in the presence of a dentin barrier, photobiomodulation can exert significant biological effects, supporting its use as an adjunctive strategy to preserve the integrity of the dentin–pulp complex.