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Back-scattered-light diagnostics of enamel and dentin surfaces

The theoretical model of coherent light scattering on enamel and dentin surface is described. The surfaces of hard tooth tissues are represented as 3D rough structures. The enamel components are assumed to form mosaic structure consisting of enamel prisms and interprism space elements. The possible tilt of enamel prisms is accounted. The dentin elements are represented as a set of shell-enclosed cylinders placed into bulk substance. The presence of peritubular dentin with refraction and absorption indices different to bulk dentin ones inside dentinal tubules is accounted. The results of computer simulation of laser radiation scattering on rough surfaces of enamel and dentin are represented. The dependencies of far-field axial intensity and FWHM of back-scattered light field on parameters of hard tooth tissue surfaces are calculated. The experimental set-up for examination of hard tooth tissues surfaces via parameters of back-scattered He-Ne laser radiation is designed. The investigation of laser radiation back-scattering on enamel and dentin surfaces is carried out. The experimental results are compared with theoretical predictions.