[Incipient cariogenic demineralization of human enamel]. / La desmineralización cariogénica incipiente en el esmalte humano.

32 teeth (12 premolars and 20 molars) were studied under light microscopy, polarized microscopy, transparence light microscopy and scanning electron microscopy. These teeth presented changes in colour in their free and proximal surface as well as close to pits and fissures. As an extra diagnostic test the PAS reaction was used to assess descalcifying processes in both light and transparence microscopy. Polarized light was used to assess normal enamel. Scanning electron microscopy corroborated the lesions produced in the enamel surface in the form of micropores. PAS reaction diagnosed decalcifying processes in yellow, brown and brownish stains. White staims not always were PAS-positive and when they reacted in the same manner as other positive stains, with the immersion technique. This penetrated 40-60 umtrs. and in some areas in relation to lamellae they reached dentin. Light, polarized and scanning electron microscopy showed the presence of micropores in the external surface of enamel in PAS-positive cases. The possibility of a modified PAS technique to use in clinical practice is discussed. It is concluded that PAS relation is useful as "ex situ" test to detect the first signs of mineral salt loss at the enamel surface. More research is needed to transfer these results to clinical practice.