Light transmittance of the periodontium

Abstract

Objective Photobiomodulation (PBM) therapy stimulates cells and regulates their activities. However, the actual accumulated dose that the cells receive is still unknown because the transmittances of the light on various tissues are not available. The objective of this study is to determine the light transmittances of the oral tissues. Methods Tissue samples of gum, cortical bone, and trabecular bone were prepared from ten Yucatan pigs' mandibles. Both the transmittance and the attenuation coefficient in the Beer-Lambert law were used to characterize the materials' light transmittance behavior. A higher attenuation coefficient indicates lower transmittance. The samples were tested with the light within the wavelength ranging from 420 to 1050 nm. The light intensity measured with and without the samples was used to calculate the transmittance. Results The result showed that the Beer-Lambert law can be used to estimate the transmittance if the light surface loss is eliminated. Among the three tissues, the gum has the highest attenuation coefficient and the trabecular bone has the lowest. The attenuation coefficient is higher at lower wavelengths for all three tissues, and is lower and keeps plateaued at the wavelength from 700 to 1050 nm. The surface loss rate of gum is higher at lower wavelengths. The light intensity within the tested range does not affect the transmittance.