[The outermost enamel layer. A comparative scanning electron microscopic study].
The surface of the enamel layer was scanned in teeth of some representative animal species. We studied the structural organization of enamel at the surface of the teeth and also in subsurface. The surface layer was often described as "aprismatic". But, nevertheless, in mammals, prisms often reach the surface. They are packed together almost perpendicular to the periphery. The term "aprismatic" seems inappropriate. But the surface layer is particular in both a structural, physical and chemical standpoint. Its distribution on the enamel surfaces explains the variability of the etching patterns from an area to another on the same tooth.