Red LED Photobiomodulates the Metabolic Activity of Odontoblast-Like Cells

Abstract

Phototherapy has been indicated as an adjunctive treatment for tissue repair, including the pulp tissue. However, there are no defined irradiation parameters, which is a great challenge to the clinical use of phototherapy. The aim of this study was to evaluate the effect of phototherapy with red LED on odontoblast-like MDPC-23 cells, using different parameter settings. Cells were seeded (10 4 cells/cm²), incubated for 12 h in complete DMEM and then the culture medium was replaced by DMEM supplemented with 0.5% FBS. After 12 h incubation, irradiations were performed (630±10 nm) using a LEDTable device with a 20 or 40 mW/cm² power density and 2 J/cm² energy dose. The cells were irradiated 1 or 3 times, at 1 min intervals. Non-irradiated cells served as control. The cells were evaluated for viability (MTT assay), total protein dosage (Lowry method) and number of viable cells (Trypan blue). The data (n=12 per group) were submitted to Kruskal-Wallis and Mann-Whitney tests (p=0.05). A single irradiation with 20 or 40 mW/cm² enhanced cell viability, which was negatively affected after 3 consecutive irradiations. Cells irradiated only once with 20 mW/cm² produced more proteins compared with those irradiated with 40 mW/cm². Reduction in the number of viable cells occurred only after 3 consecutive irradiations with 40 mW/cm². In conclusion, red LED was capable of biomodulating the metabolic activities of cultured MDPC-23 odontoblast-like cells. The best cell biostimulation was obtained when a single irradiation with 2 J/cm 2 energy dose and 20 mW/cm 2 power density was delivered to the pulp cells. R e d L E D P h o t o b i o m o d u l a t e s t h e M e t a b o l i c A c t i v i t

Development and application of LED arrays for use in phototherapy research

“…However, the adjustable potentiometers of the broad range array allowed calibration to standardize the irradiance to achieve a baseline irradiance value of 3.5 mW/cm 2 at each wavelength (Figure ). This value was chosen since our previous study reported the stimulation of DPCs using red light emitting diodes (653 nm) at similar irradiance although other irradiances have also been shown to be effective for DPC stimulation. Furthermore, a lower irradiance is likely to be more clinically relevant since attenuation by dental tissues will reduce the irradiance delivered to dental pulp cells .…”

“…Within a dental context, favourable data exists for oral health related conditions including oral mucositis [10], dentine hypersensitivity candidiasis and others . Odontoblast‐like cell modulation has also been reported which has significance for treatment of diseases such as dental caries . Stimulation of the dentine‐pulp complex has been shown to modulate oxidative stress and promote natural repair processes through reactive oxygen species (ROS) activation of latent transforming growth factors (TGF‐β1).…”

“…Stimulation of the dentine‐pulp complex has been shown to modulate oxidative stress and promote natural repair processes through reactive oxygen species (ROS) activation of latent transforming growth factors (TGF‐β1). Subsequently, activation of these processes reportedly triggers the differentiation of stem cells into odontoblast‐like cells necessary for dental tissue regeneration .…”

Photobiomodulation effect of red LED (630 nm) on the free radical levels produced by pulp cells under stress conditions

“…The irradiation of cultured pulp cells was performed using a LED table; this device is widely employed in laboratorial studies in this research field (Fig. 1) [2,22,23,[39][40][41]. The LED table was developed by the Optical Group (OG) of the Optics and Photonics Research Center (Centro de Pesquisa em Óptica e Fotônica -CePOF) of the São Carlos Institute of Physics (IFSC) at the University of São Paulo (USP).…”

“…The potential beneficial parameters (4 J/cm 2 , 15 J/cm 2 , and 30 J/cm 2 at 0.04 W/cm 2 ) [20,23,30,39,40], as well as more intense parameters, which may be considered to be potentially harmful to the cells (4 J/cm 2 , 15 J/cm 2 , and 30 J/cm 2 at 0.08 W/cm 2 ), were assessed. The irradiation parameters used in this study are shown in Tables 2 and 3.…”