AMELOGENESIS IMPERFECTA AND NEPHROCALCINOSIS SYNDROME - CASE-STUDIES OF CLINICAL-FEATURES AND ULTRASTRUCTURE OF TOOTH ENAMEL IN 2 SIBLINGS

This article describes the enamel ultrastructure and clinical features in two siblings with the little known syndrome of Amelogenesis imperf ecta and nephrocalcinosis. Nephrocalcinosis was diagnosed by x-ray exa mination of the abdomen, intravenous pyelography, ultrasonography, and computed tomography scan. Amelogenesis imperfecta was diagnosed from clinical and histologic examinations. The affected enamel was hypoplas tic (similar to 0.2 mm thick), positively birefringent, generally apri smatic, porous, and consisted of loosely packed, randomly orientated, thin (similar to 10 nm wide), ribbonlike crystals. The enamel surface was rough, extensively cracked, and covered with ovoid or globular pro trusions. Observations showed that in this case hypoplasia, hypocalcif ication, or hypomaturation defects were present in the same tooth, ind icating that both secretory and maturation phases may have been affect ed. The study suggested the possibility of an abnormality in interstit ial matrix, which could lead to dystrophic calcification in the kidney and abnormal tooth enamel formation. It also suggested the possibilit y of involvement of two separate but closely linked genes.