HeNe-laser light scattering by human dental enamel

Knowledge of the optical properties of tooth enamel and an understanding of the origin of these properties are necessary for the development of new optical methods for caries diagnosis and the measurement of tooth color. We measured the scattering intensity functions for HeNe-laser light of 80- to 100-mu m-thick human dental enamel slabs. The asymmetry factors were calculated to be g = 0.68 at 633 nm. By measuring the collimated beam attenuation, we determined the scattering coefficient to be s = 6.6 mm(-1). From Fraunhofer diffraction patterns, obtained from transmission of the laser beam, we calculated the periodicity of the prismatic structure as 5.4 mu m. We present a model containing scattering by crystals and by prisms. It shows that the prisms are the most important scatterers but that the crystals are responsible for the back-scattering.