Effect of low-level GaAlAs laser irradiation on the proliferation rate of human periodontal ligament fibroblasts: an in vitro study

J Clin Periodontol. 2003 Apr;30(4):353-8. doi: 10.1034/j.1600-051x.2003.00001.x.


Aim: The aim of this in vitro study was to evaluate a potential stimulatory effect of low-level laser irradiation on the proliferation of human periodontal ligament fibroblasts (PDLF).

Materials and methods: PDLF obtained from third molar periodontal ligaments were cultured under standard conditions and spread on 96-well tissue culture plates. Subconfluent monolayers were irradiated with an 809-nm diode laser operated at a power output of 10 mW in the continuous wave (cw) mode at energy fluences of 1.96-7.84 Jcm-2. The variable irradiation parameters were the time of exposure (75-300 s per well) and the number of irradiations (1-3). After laser treatment, the cultures were incubated for 24 h. The proliferation rate of the lased and control cultures was determined by means of fluorescence activity of a reduction-oxidation (REDOX) indicator (Alamar Blue Assay) added to the cell culture. Proliferation, expressed in relative fluorescence units (RFU), was determined 24, 48 and 72 h after irradiation.

Results: The irradiated cells revealed a considerably higher proliferation activity than the controls. The differences were significant up to 72 h after irradiation (Mann-Whitney U-test, p<0.05).

Conclusion: A cellular effect of the soft laser application is clearly discernible. Clinical studies are needed to evaluate whether the application of low-level laser therapy might be beneficial in regenerative periodontal therapy.

MeSH terms

  • Aluminum
  • Arsenic
  • Cell Division / radiation effects
  • Cells, Cultured
  • Coloring Agents
  • Fibroblasts / radiation effects*
  • Fluorescence
  • Gallium
  • Humans
  • Indicators and Reagents
  • Lasers*
  • Oxazines*
  • Periodontal Ligament / cytology
  • Periodontal Ligament / radiation effects*
  • Radiation Dosage
  • Statistics, Nonparametric
  • Time Factors
  • Xanthenes*


  • Coloring Agents
  • Indicators and Reagents
  • Oxazines
  • Xanthenes
  • resazurin
  • Gallium
  • Aluminum
  • Arsenic