Main problem in interpreting polarized light microscopy of dental enamel

The main problem in interpreting poelarized ligth micrsocopy image of dental enamel is that the theoretical and the experimental ename brefringences are not consistent. Thas is, for mature enamel (mineral volume of 87%) immersed in water (refractive index = 1.33), the theoretical form birefringence (from the Weiner equation) is too high, +0.007, yielding a positive observed birefringence, while mature enamel is known to present negative observed birefringence when immersed in water. This is the reason why quantitative data on the enamel's mineral volume cannot be derived from PLM.

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