The effect of UV-Vis to near-infrared light on the biological response of human dental pulp cells

Mohammed A. Hadis*, Paul R. Cooper, Michael R. Milward, Patricia Gorecki, Edward Tarte, James Churm, William M. Palin

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Citation (Scopus)


Human dental pulp cells (DPCs) were isolated and cultured in phenol-red-free α-MEM/10%-FCS at 37°C in 5% CO2. DPCs at passages 2-4 were seeded (150μ1/4L; 25,000 cell/ml) in black 96-microwell plates with transparent bases. 24h post-seeding, cultures were irradiated using a bespoke LED array consisting of 60 LEDs (3.5mW/cm2) of wavelengths from 400-900nm (10 wavelengths, n=6) for time intervals of up to 120s. Metabolic and mitochondrial activity was assessed via a modified MTT assay. Statistical differences were identified using multi-factorial analysis of variance and post-hoc Tukey tests (P=0.05). The biological responses were significantly dependent upon post-irradiation incubation period, wavelength and exposure time (P<0.05). At shorter wavelength irradiances (400nm), a reduction in mitochondrial activity was detected although not significant, whereas longer wavelength irradiances (at 633, 656, 781 and 799nm) significantly increased mitochondrial activity (P<0.05) in DPCs. At these wavelengths, mitochondrial activity was generally increased for exposures less than 90s with 30s exposures being most effective with 24h incubation. Increasing the post-irradiation incubation period increased the measured response and identified further significance (P<0.05). The biological responses of human DPCs were wavelength, exposure-time and incubation period dependent. The optimisation of irradiation parameters will be key to the successful application of LLLT in dentistry.

Original languageEnglish
Title of host publicationProgress in Biomedical Optics and Imaging - Proceedings of SPIE
PublisherSociety of Photo-Optical Instrumentation Engineers
ISBN (Print)9781628413991
Publication statusPublished - 2015
EventMechanisms for Low-Light Therapy X - San Francisco, United States
Duration: 7 Feb 20158 Feb 2015


ConferenceMechanisms for Low-Light Therapy X
Country/TerritoryUnited States
CitySan Francisco


  • dose
  • LED
  • LLLT
  • MTT
  • photobiomodulation
  • wavelength

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Radiology Nuclear Medicine and imaging


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