Regional odontodysplasia: new histopathological data.

Light microscopy, microradiography, SEM and TEM of 4 tooth follicles in a 12-year-old caucasian girl presenting regional odontodysplasia showed widespread globular dentin, calcifications located in the enlarged pulp chambers, hypoplastic and hypomineralized enamel. Hypomineralized strands were sandwiched between two normal enamel layers, which indicates that amelogenesis, interrupted for a while, has once more become established. The enamel surface was covered with calcoglobules. Numerous rounded calcifications were scattered within the dental follicles. Some of these occurred in microfibrils (possibly oxytalan fibers), distinct from collagen fibers. Calcification of the sheath surrounding epithelial rests was a conspicuous feature. The fibroblasts in contact with calcifications developed numerous cytoplasmic extensions, which suggests that they may have assumed a phagocytosis behaviour.