ULTRASTRUCTURE OF DENTIN MATRIX IN HERITABLE DENTIN DEFECTS

Heritable dentin defects form a group of diseases which exclusively af fect dentin among the various dental tissues. While one type is associ ated with the generalized connective tissue disorder, osteogenesis imp erfecta, other types occur as single traits. The clinical manifestatio ns of the dentin defects vary from insignificant to severe enough to c ause aesthetical and functional failure of the teeth. Scanning and tra nsmission electron microscopic studies, reviewed in this paper, have m arkedly clarified the ultrastructure of the aberrant dentin matrix. Bo th similar and different changes seem to occur in the various forms of heritable dentin defects. Abnormalities in the appearance and organiz ation pattern of collagen fibers in the defective dentin partly resemb le those observed in skin in generalized connective tissue diseases. T he similarity of ultrastructural findings in dentin defects, which are currently classified as distinct entities, and even in diseases affec ting other tissues, could be related to the complicated interactions b etween the extracellular matrix macromolecules. Thus, many of the chan ges observed may be secondary in nature. Ultrastructural studies can h elp us to understand the pathogenesis of the different types of herita ble dentin defects as well as aid in diagnostics and classification of these diseases.