Optical Changes in Dentin as a Function of Mineral Content

Objectives: The optical properties of human dentin can change markedly due to aging, friction from opposing teeth, and acute trauma, resulting in the formation of transparent or sclerotic dentin with increased mineral density. The objective of this study was to determine the optical attenuation coefficient of human dentin tissues with different mineral densities in the near-infrared (NIR) spectral regions from 1500-2200 nm using NIR transillumination and optical coherence tomography (OCT).
Methods: N=50 dentin samples of varying opacities were obtained by sectioning whole extracted teeth into ≈150μm transverse sections at the cement-enamel junction and the apical root. Transillumination images were acquired with a NIR camera and attenuation measurements were acquired at various NIR wavelengths using a NIR light source and InGaAS detector. Samples were imaged with transverse microradiography (gold standard) in order to determine each samples mineral density.
Results: Light attenuation varied markedly with mineral content and wavelength at extended NIR wavelengths
Conclusions: Longer wavelengths may be more effective for imaging through dentin.