Beam profile measurements for dental phototherapy: The effect of distance, wavelength and tissue thickness

William M. Palin*, Mohammed A. Hadis, Michael R. Milward, James D. Carroll, Paul R. Cooper

*Corresponding author for this work

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

2 Citations (Scopus)


Light delivery for potential bacterial disinfection (UV/blue) and photobiomodulation (near-IR) requires specific, concentrated and controllable local irradiance and dose. Dental targets for light irradiation involve dentine, which scatters, absorbs and reflects light, reducing local irradiance. This study compared the effectiveness of LEDs (400-900nm) and lasers (660nm and 810nm) to penetrate dentine. Caries-free wisdom teeth were sectioned through the Pulpchamber by either cutting perpendicular to the crown, the buccal aspect or obliquely. Specimens were wet-polished to 1, 2 or 3mm thicknesses to expose the dentine on opposing surfaces. The beam profile of the LEDs/lasers were measured through dentine specimens (n=5) to obtain beam width following optical calibration, and spatial irradiance distribution following photodiode power calibration. There were no significant differences in the percentage power and irradiance transmitted through different dentine specimens between LEDs and lasers (P>0.05). However, light penetration through tissue was wavelength dependent and highest for red and near-IR wavelengths (P<0.05) for specimens cut perpendicular to the crown compared with buccal and oblique specimens. The beam diameters increased and irradiance decreased significantly (P<0.05) with increasing specimen thickness/distance for both LEDs and lasers. There was a noticeable shift in beam position for all light sources in buccal and oblique specimens. Data indicated that dentine tubule orientation may alter the direction of light through the tissue. Optimal light penetration and distribution through dentine at specific distance is best achieved with a flat-top beam distribution vertically through the crown of the toot.

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


  • beam profile
  • LLLT
  • photobiomodulation
  • transmission through dentine

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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