A Comparative Analysis of Photobiomodulation-Mediated Biological Effects of Single Versus Double Irradiation on Dental Pulp Stem Cells: An In Vitro Study

Photobiomodul Photomed Laser Surg. 2022 May;40(5):334-342. doi: 10.1089/photob.2021.0134.


Objective: In recent years, fractionated irradiation protocols, rather than a simple plan of exposure, have been proposed as a more effective method in the field of tissue regeneration. Thus, this study aimed at a comparative analysis of single versus double irradiation of an 808-nm diode laser, in terms of dental pulp stem cells' (DPSCs) viability and proliferation in vitro. Methods: Subcultured DPSCs were either irradiated, or not (control group), with energy densities of 3, 7, and 12 J·cm-2 in a single- or double-session manner (24 h apart). On 0, 12, 24, 48, and 72 h postirradiation, cell viability and proliferation were evaluated through Trypan Blue and alamarBlue assays, respectively. Results: During the first 48 h postirradiation, the highest rates of DPSC proliferation were assigned to double irradiation at 3 or single exposure to 7 J⋅cm-2, with no cytotoxic effects on cell viability. Inversely, single irradiation at 12, or a double session of exposure to 7 or 12 J⋅cm-2, led to a significant descent in the rates of proliferation and cell viability. Conclusions: Within the limitations of this study, evidence suggests a positive impact on the biological responses of DPSCs following double session of exposure to lower energy densities as well as a single irradiation at a higher energy dosage.

Keywords: dental stem cell; laser therapy; photobiomodulation.

MeSH terms

  • Cell Proliferation / radiation effects
  • Dental Pulp
  • Lasers, Semiconductor / therapeutic use
  • Low-Level Light Therapy*
  • Stem Cells / radiation effects