Transmission electron microscopic appearance of dentin matrix in type II dentin dysplasia.

Dentin matrix of demineralized primary and permanent teeth with type II dentin dysplasia was studied by transmission electron microscopy. The coronal dentin of a maxillary third molar exhibited a normal structure. In the radicular dentin, tubules were few in number; the major part of the dentin was composed of thick, curvy bundles of cross-striated collagen fibers. In the most aberrant areas of the radicular dentin, coarse collagen fibers measuring up to 140 nm in thickness were observed. The dentin of the primary tooth showed a similar, but somewhat less irregular, structure.