Light scattering properties of bovine muscle tissue in vitro, a comparison of methods

We measured the light scattering properties of muscular tissue using several methods, and compared the obtained results. Calculation of the extinction coefficient by using collimated transmission measurements and applying Beer's law is not appropriate. Probably surface roughness of the sample disables the calculation of the extinction coefficient from such measurements. From angular intensity measurements we found a scattering asymmetry parameter g = 0.96. In fresh samples the optical diffusion constant D depends on the orientation with respect to the longitudinal direction of the muscular cells. From the D values we calculated s' perpendicular to the longitudinal direction as 0.19 mm(-1) (at 543 nm), 0.39 mm(-1) (at 594 nm) and 0.59 mm(-1) (at 632 nm). The values for D measured from samples that were frozen and thawed did not show dependence on orientation.</p

Monitoring dental erosion by colour measurement: an in vitro study.

Contains fulltext : 70544.pdf (publisher's version ) (Closed access)OBJECTIVES: The aim of this study was to develop a method to monitor dental erosion by evaluation of the colour change of teeth as a function of enamel loss, and to evaluate the reproducibility of the method used. METHODS: Light reflectance spectra of 12 extracted human incisors were measured using a spectroradiometer and diffuse illumination. From these spectra CIELab colour parameters L*, a* and b* were calculated. Erosive dental wear was simulated by incrementally removing enamel layers. We monitored the change of the colour parameters as a function of the enamel thickness removed. A clinical situation using a phantom head and ambient illumination was simulated with 8 incisors. In this set-up colour change due to polishing was evaluated. The teeth were immersed in coffee and tea to estimate the effects of nutritional dyes, and so, to determine reproducibility of the method used in clinical situations. RESULTS: A relationship between tooth colour measured and enamel loss was found, in particular for the b* value. The relation between the b*-value and the enamel thickness removed showed a slope of 15+/-3mm(-1), if the remaining enamel layer had a thickness of less than 0.5mm. Polishing of the teeth made them less yellow. Immersion in coffee darkened the teeth, but immersion in tea had no significant effect. CONCLUSIONS: Due to individual variation, it was impossible to use this relationship to estimate the remaining enamel thickness, but the method presented may be suitable for monitoring progression of erosive enamel loss

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

Light scattering properties of bovine muscle tissue in vitro, a comparison of methods

We measured the light scattering properties of muscular tissue using several methods, and compared the obtained results. Calculation of the extinction coefficient by using collimated transmission measurements and applying Beer's law is not appropriate. Probably surface roughness of the sample disables the calculation of the extinction coefficient from such measurements. From angular intensity measurements we found a scattering asymmetry parameter g = 0.96. In fresh samples the optical diffusion constant D depends on the orientation with respect to the longitudinal direction of the muscular cells. From the D values we calculated s' perpendicular to the longitudinal direction as 0.19 mm(-1) (at 543 nm), 0.39 mm(-1) (at 594 nm) and 0.59 mm(-1) (at 632 nm). The values for D measured from samples that were frozen and thawed did not show dependence on orientation