X-ray Phase Contrast Imaging of Dental Tissues

Objectives: Recently developed phase-contrast imaging using a highly coherent monochromatic X-ray was applied to dental hard tissues. Phase-contrast imaging was not a type of simple absorption but a type of phase contrast microscopy, and make clear the boarders of materials having very slight different refractive indices. Methods: Wavelength-tunable monochromatic coherent Parametric X-ray generated at LEBRA, Nihon University, was applied to this experiment. The X-rays from 5 keV (0.248 nm) to 34 keV (0.03647 nm) range were used. Diffraction enhanced imaging (DEI) methods was adopted for the phase contrast technique and computed tomography was achieved utilizing DEI data. Sample of whole tooth or sectioned was placed on a Imaging Plate (Fuji Film), and exposed for several tens minutes. Results: Dentin and enamel were clearly discriminated similar to as using a normal X-ray imaging. Cementum was also clearly distinguished. High resolution imaging revealed the presence of interglobular spaces in the dentin. In the cases of carious teeth, carious cones in the enamel and dentin were visible. Conclusions: High contrast imaging of dental tissues could be obtained applying the X-ray phase-contrast imaging. Since the phase-contrast imaging improves the low contrast images of materials with low X-ray absorption coefficients, this method is of possible relevance in the imaging of the soft tissues.