Comments on the porosity of human tooth enamel.

The porous nature of surface and sub-surface enamel undergoing the final stages of maturation has been observed on unerupted, partly-erupted, and fully-erupted human teeth, using polarized light microscopy, microradiography, and scanning electron microscopy. Maturation deficiency of developmental origin can be distinguished from early carious lesions with polarized light by the absence of a well-circumscribed "dark" zone.