Transdentinal photobiostimulation of stem cells from human exfoliated primary teeth

The efficacy of infrared diode laser in enhancing the regenerative potential of human periodontal ligament stem cells (hPDLSCs)

BACKGROUND

The present study aimed to investigate the effects of infrared diode laser irradiation on the proliferation and differentiation capacity of periodontal ligament stem cells (hPDLSCs), which are optimal cell sources for periodontal regeneration.

METHODS

hPDLSCs were isolated and characterized by flow cytometric analysis of mesenchymal stem cell markers, and their trilineage differentiation capacity was tested. hPDLSCs were then cultured and irradiated with infrared diode laser (970 nm) at a power of 200 mW and a fluence of 4 J/cm2 for 3 s. MTT assay was performed to assess cellular proliferation. Cell cycle analysis was performed, and the impact of infrared diode laser irradiation on the stemness and osteogenic differentiation potential of hPDLSCs was evaluated via RT‒PCR.

RESULTS

Infrared diode laser application enhanced the stemness, viability, proliferation, and differentiation of PDLSCs. Stem cell markers (OCT4, SOX2, and NANOG) were significantly upregulated in hPDLSCs exposed to laser irradiation. There was significant overexpression of RUNX2, ALP, OPN, and OCN on day 14 after laser application.

CONCLUSIONS

These findings provide valuable insights into the specific applications of infrared diode lasers to effectively regenerate periodontal tissues. The results can aid in the development of precise clinical protocols aimed at enhancing osseointegration and promoting tissue regeneration. Ultimately, the combination of infrared diode laser with hPDLSCs is promising for stimulating periodontal regeneration.

Effects of Semiconductor Laser Irradiation on Differentiation of Human Dental Pulp Stem Cells in Co-Culture with Dentin

This study aimed to determine the effect of photobiomodulation therapy induced by semiconductor laser irradiation on human dental pulp stem cell (hDPSC) proliferation and their differentiation into odontoblast-like cells (OLCs). The effects of various semiconductor laser irradiation conditions on hDPSCs were examined. Three groups were evaluated: a single laser irradiation at 6 h post-seeding, multiple laser irradiations up to four times every 4 days after the first dose, and a control with no laser irradiation. The cells were irradiated at 10, 30, and 150 mW using a semiconductor laser. The effect of laser irradiation on hDPSC differentiation into OLCs was also determined. Four groups were evaluated, including co-culture using basic medium and dentin discs, simple culture using OLC differentiation-inducing medium, co-culture using OLC differentiation-inducing medium and dentin discs, and control culture with basic medium. The expression of the nestin, ALP, DSPP, and DMP-1 genes was measured using real-time PCR. The multiple irradiation group irradiated at 30 mW exhibited significantly more cell proliferation than the control. The expression of nestin associated with differentiation into OLCs during each culture period tended to be lower, whereas DSPP and ALP expression was higher compared with that of the control. Multiple laser irradiations at a low power of 30 mW induced significant hDPSC proliferation and might induce differentiation into OLCs.

Viability and oxidative stress of dental pulp cells after indirect application of chemomechanical agents: An in vitro study

AIM

This study evaluated the transdentinal cytotoxic effects of enzymatic agents (EA) for chemomechanical carious tissue removal on human dental pulp cells.

METHODOLOGY

The groups were based on the performed dentine treatments (n = 8): G1: Positive Control (PC - no treatment); G2: Negative Control (NC - 35% H2 O2 for 2 min); G3: Brix 3000™ (BX) for 30 s; G4: BX for 2 min; G5: Papacarie Duo™ (PD) for 30 s; G6: PD for 2 min. The cells were evaluated for viability (VB; MTT assay) and production of reactive oxygen species (ROS; DCFH-DA assay) and nitric oxide (NO; Griess reagent). A scanning electron microscope provided morphological chemical analyses and energy-dispersive X-ray spectroscopy. The data were submitted to the one-way anova statistical test complemented by Tukey (p < .05).

RESULTS

Cell viability decreased by 21.1% and 58.4% in G5 and G6, respectively. ROS production in G3 and G4 maintained basal levels but increased by 171.2% and 75.1% in G5 and G6, respectively.

CONCLUSIONS

The Brix3000™ enzymatic agent did not cause indirect cytotoxic effects on pulp cells, regardless of the application time. Conversely, Papacarie Duo™ reduced viability and increased ROS production by pulp cells.

The Role of Photobiomodulation on Dental-Derived Stem Cells in Regenerative Dentistry: A Comprehensive Systematic Review

BACKGROUND

Photobiomodulation therapy involves exposing tissues to light sources, including light-emitting diodes or low-level lasers, which results in cellular function modulation. The molecular mechanism of this treatment is revealed, demonstrating that depending on the light settings utilized, it has the potential to elicit both stimulatory and inhibitory reactions.

OBJECTIVE

The current systematic review aimed to evaluate the impact of photobiomodulation therapy on dental stem cells and provide an evidence-based conclusion in this regard.

METHODS

This systematic review was performed and reported based on the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) revised guidelines. PICO(S) components were employed to define the inclusion criteria. Web of Science, Scopus, Medline as well as grey literature, and google scholar were searched up to September 2021 to retrieve relevant papers.

RESULTS

Photobiomodulation therapy showed promising effects on the proliferation, viability, and differentiation of dental stem cells. This finding was based on reviewing related articles with a low risk of bias.

CONCLUSION

Despite the positive benefits of photobiomodulation therapy on dental stem cells, the current data do not provide a definitive conclusion on the best physical parameters for enhancing cell viability, proliferation, and differentiation.

Effect of diode low level laser and red light emitting diode irradiation on cell proliferation and osteogenic/odontogenic differentiation of stem cells from the apical papilla

BACKGROUND

This experimental study aimed to assess the effect of irradiation of red light-emitting diode (LED) and Diode low-level laser (LLL) on osteogenic/odontogenic differentiation of stem cells from the apical papilla (SCAPs).

MATERIALS AND METHODS

SCAPs were isolated from the human tooth root. The experimental groups were subjected to 4 J/cm² diode low level laser and red LED irradiation in osteogenic medium. The control group did not receive any irradiation. Cell viability/proliferation of SCAPs was assessed by the methyl thiazolyl tetrazolium (MTT) assay on days 1 and 2 (n = 9). Osteogenic differentiation was evaluated by alizarin red staining (ARS) (n = 3), and expression of osteogenic genes by real-time polymerase chain reaction (RT-PCR) (n = 12) on days 1 and 2. SPSS version 18 was used for data evaluation. The Kruskal-Wallis and Mann-Whitney tests were used to compare the groups at each time point.

RESULTS

The MTT assay showed no significant difference in cell viability/proliferation of SCAPs in the low level laser, red LED, and control groups at 24 or 48 h (P < 0.001). The ARS assessment showed that low level laser and red LED irradiation enhanced osteogenic differentiation of SCAPs. low level laser and red LED irradiation both induced over-expression of osteogenic/dentinogenic genes including alkaline phosphatase (ALP), dentin sialophosphoprotein (DSPP), dentin matrix protein 1 (DMP-1), and bone sialoprotein (BSP) in SCAPs. Up-regulation of genes was significantly greater in low level laser irradiation group than red LED group (P < 0.001).

CONCLUSION

Diode low level laser irradiation with 4 J/cm² energy density and red LED irradiation enhanced osteogenic differentiation of SCAPs without adversely affecting cell viability.

Specific parameters of infrared LED irradiation promote the inhibition of oxidative stress in dental pulp cells

OBJECTIVES

The present study aimed to assess the oxidative stress and the viability of dental pulp cells stimulated by lipopolysaccharide (LPS) and submitted to photobiomodulation (PBM) with infrared light-emitting diode (LED, 850 nm).

DESIGN

Three healthy primary teeth (n = 3) were collected and seeded in 24-well plates with 10 µg/mL of LPS to induce inflammatory mediator formation. The cells were irradiated (850 nm, 40 mW/cm² and 80 mW/cm²) at the proposed radiant exposures of 0 (control), 4, 15, and 30 J/cm² shortly after LPS supplementation. The tests were performed 24 h after irradiation to assess mitochondrial activity (MTT assay), the number of viable cells (Trypan Blue), cell morphology (Scanning Electron Microscopy - SEM), and the quantification of Nitric Oxide (NO) and Reactive Oxygen Species (ROS). The data were analyzed using Kruskal-Wallis and Dunn's tests (p < 0.05).

RESULTS

The irradiated groups showed larger viable cells number than the non-irradiated group with LPS (p < 0.0001). All irradiation parameters decreased ROS concentrations after LPS application compared to the non-irradiated group (p < 0.05). All irradiation parameters enhanced the NO values compared to those of the control group (p < 0.05). The SEM images showed cells with regular morphology that adhered to the substrate.

CONCLUSIONS

According to the parameters used in this study, the radiant exposure of 15 J/cm² and irradiance of 40 mW/cm² were the most effective irradiation parameters to stimulate and modulate oxidative stress in the primary teeth-derived dental pulp cells.

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

The aim of this study was to assess the ability of red light emitting diodes (LED) to modulate oxidative stress in human dental pulp fibroblasts (HDPFs) when different irradiation parameters are employed. Cells from primary teeth were seeded (100,000 cells/well) in 24-well plates in culture medium (DMEM). At 24 h after incubation, the culture medium was replaced with DMEM containing 10 μg/mL lipopolysaccharide (LPS). Thereafter, the cells were irradiated (LED 630 nm, 0.04 W/cm² and 0.08 W/cm²) at 0 J/cm² (control group), 4 J/cm², 15 J/cm², and 30 J/cm²; and their viability (MTT assay), number (Trypan Blue), synthesis of nitric oxide (NO) (Griess reagent), and reactive oxygen species (ROS) (fluorescence probe, DCFH-DA) were assessed. The Kruskal-Wallis and Mann-Whitney statistical tests using Bonferroni correction were employed (significance level of 5%). Compared to that in control fibroblasts, increased viability was observed in HDPFs exposed to LPS and irradiated with 15 J/cm² and 30 J/cm² at 0.04 W/cm² and 4 J/cm² and 15 J/cm² at 0.08 W/cm² (p < 0.05). Exposure to 4 J/cm² at 0.04 W/cm² and 15 J/cm² and 30 J/cm² at 0.08 W/cm² modulated the oxidative stress in cells relative to that observed in non-irradiated LPS-treated pulp cells (p < 0.05). It was concluded that the irradiation strategies of using red LED with radiant exposures of 15 J/cm² and 30 J/cm² at 0.04 W/cm² and 15 J/cm² at 0.08 W/cm² were the best parameters to decrease NO and ROS concentration and to stimulate viability of HDPFs exposed to LPS challenge.