[The structure, ultrastructure and physicochemical analysis of the hard dental tissues of the Viperidae]

The present study, using classical microscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, infrared spectroscopy, has shown the dental hard tissues of the fangs of Viperidae (poisonous serpents with terrestrial or semi-aquatic habits) to be constituted of: a calcified outer layer, 0.4 microns thick, made of very small needle-like crystals, randomly distributed. The calcified outer layer contains organic invaginations inducing pores at the surface and many collagen fibres incompletely mineralized, which may suggest enameloid. a calcified inner layer, in the wall of the poison canal. The calcified inner layer, 0.6 microns thick, is constituted of very small crystals, which are parallel to each other and perpendicular to the calcified outer layer. It might be the inner layer of enameloid, an orthodentine, whose tubules present a special lateral branching system resembling a fish bone. The TEM data, which show the dentine to be constituted of very small ill-defined crystals and incompletely mineralized collagen fibres are corroborated by chemical analyses which reveal a poorly mineralized apatite with high carbonate content.