Regional odontodysplasia: morphological, ultrastructural, and immunohistochemical features of the affected teeth, connective tissue, and odontogenic remnants.

PURPOSE: Regional odontodysplasia (RO) is a rare developmental odontogenic defect. The affected teeth are described as "ghost teeth," due to malformation of dentin, enamel, and cementum. The purpose of this study was to describe the ultrastructural characteristics of the affected teeth as well as the immunohistochemical features of the soft tissue associated with 2 cases of regional odontodysplasia.

METHODS

Two cases diagnosed as RO were included on the study. After diagnosis, affected teeth and associated soft tissue were surgically removed from both patients and processed for light and scanning electron microscopy (SEM) analysis. For light microscopy, the specimens were decalcified in 5% nitric acid for 10 to 16 days and stained with hematoxylin and eosin. For SEM studies, specimens were cleaned with diamond paste and, after polishing, treated with 37% phosphoric acid for 5 minutes and covered by a thin layer of metallic gold. Soft tissues covering and surrounding the extracted teeth were routinely processed, and submitted to immunohistochemical reactions against pan-cytokeratins, cytokeratin 19, vimentin, laminin and collagen IV.

RESULTS

Both enamel and dentin showed gross alterations, including hypomineralization and discoloration, being more prominent on the coronal structures than the radicular structures. Ultrastructural features included alterations on the prismatic enamel surface, dentinal grooves, interglobular dentin, and hypoplastic and hypocalcified dental hard tissues. The soft gingival and alveolar tissue surrounding and covering the affected teeth showed calcifications and odontogenic remnants, positive for cytokeratin 19, laminin, and collagen IV.

CONCLUSIONS

Enamel and dentin are grossly altered in regional odontodysplasia, while cementum is less affected, and soft-tissue calcifications are associated with odontogenic cytokeratin-positive epithelial remnants, in addition to mesenchymal components.