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This is a report of a kindred of at least 181 members, of whom 35 exhibit or are reported to have dentin dysplasia type I. Six others are suspected of having the condition. Radiographic evidence that included obliterated or semilunar pulp chambers and short or undeveloped roots confirmed the diagnosis in 18 persons. The autosomal dominant mode of inheritance has been confirmed. One hundred percent penetrance has been demonstrated. There were insufficient data to determine the degree of expressivity.

The literature is reviewed to determine the radiographic appearance of the reported cases of dentin dysplasia. The sometimes confusing nomenclature is rationalized. Four distinct forms of dentin dysplasia type I and one form of dentin dysplasia type II are identified. There seems to be no need to identify more than two distinct types of this relatively rare inherited defect of human dentin, but a proposed subclassification of type I dentin dysplasia could make identification of the two types easier.

Radicular dentin dysplasia is a peculiar anomaly in which abnormal dentin resembling the plici-dentin found in certain fish and reptiles obliterates the pulp chamber. The almost complete absence of roots leads to the early loss of teeth and predisposes to paradontal infection and the formation of cysts.

Dentin dysplasia Type I is a rare hereditary disturbance in dentin formation characterized by teeth with short blunted roots, complete pulpal obliteration, periapical abscesses or cysts without an obvious causative factor, and spontaneous exfoliation. This report describes the clinical, radiographic, histologic, ultrastructural, and genetic features of dentin dysplasia Type I in a 17-year-old boy and discusses the features which separate it from dentin dysplasia Type II and dentinogenesis imperfecta.

A new, nonsyndromic dentin defect, focal odontoblastic dysplasia, is described on the basis of clinical, radiographic, histologic, and scanning electron microscopic criteria. A provisional classification is proposed for this disease entity according to the nosology of Shields and associates. Four additional cases in the literature which possibly represent this new entity are presented, and a possible genetic etiology is discussed.

The second reported family with an unusual dentin abnormality is presented. This abnormality is characterized by involvement of both the deciduous and the permanent dentitions, but the involvement in each is different. The deciduous teeth resemble the condition known as hereditary opalescent dentin, both clinically and radiographically. However, the permanent teeth appear normal clinically, but dilated pulpal chambers and pulp stones are evident radiographically.

Dentin dysplasia type I (DD-I) is a rare autosomal dominant disorder which affects both the deciduous and permanent dentitions. The affected deciduous and permanent teeth have short conical roots with sharp, apical constrictions and frequently periapical radiolucencies in the absence of caries. Apical to a thin layer of normal coronal dentin are large, calcified, dentin masses which nearly obliterate the pulp chamber and canals. Presented here are light microscopic and scanning electron microscopic observations of deciduous teeth from three unrelated persons with the disorder. In general, the deciduous teeth had (1) normal enamel, (2) a thin layer of normal dentin adjacent to the dentinoenamel junction, (3) a crescent-shaped pulpal remnant below the normal dentin, (4) dysplastic dentin masses (ranging from atubular to a few small tubules) between which are spaces presumed to previously have contained smaller remnants of the original mesenchymal dental papilla, and (5) root dentin, which is dysplastic throughout. The SEM-defined phenotype, however, was noticeably variable among all three persons. Based on the current concepts of tooth morphogenesis, it is most likely that the abnormal root morphology of DD-I teeth is secondary to the abnormal differentiation and/or function of the ectomesenchymally derived odontoblasts.

The first reported case of endodontic therapy in dentinal dysplasia, Type I, is described. The first histologic diagnosis of periapical granuloma instead of periapical cyst in dentinal dysplasia, Type I, is also reported.

A syndrome of scanty, fine, curled hair, thin dysplastic nails, taurodontic molars, hypoplastic-hypomature enamel, dysplasia of dentin, and hypohidrosis segregating as an autosomal dominant trait is described in a Japanese family. The patients received repeated doses of tetracycline during odontogenesis which fortuitously assisted in interpreting the pathogenesis of the dentin defect. The condition was previously described as familial congenital ectodermal dysplasia by Westerholm and as odontogenesis imperfecta by Siirilä and Heikinheimo. It is suggested that the name trichoonychodental (TOD) syndrome is a better descriptive term for the condition.

Patients with teeth showing all of the clinical, radiographic, and histologic features of radicular dentine dysplasia (type I) have been found to have dense sclerotic bone and skeletal anomalies of the wrists and hand bones. The association of these defects of teeth and bone was found to be transmitted as an autosomal dominant trait over four generations. Review of theliterature failed to disclose a previous description of this disorder.

A young man presented a condition of the teeth in which the pulp cavities were extremely large, with thin dentine walls but normal enamel. The roots were short. The size of the pulp cavities was not due to resorption, but to insufficient and defective dentine formation. The condition is compared with that found in hereditary opalescent dentine.

Metallurgically polished and fractured sections of teeth with dentinal dysplasia were prepared and studied under the scanning electron microscope. The morphologic data obtained suggested that the defect was one of the epithelial root sheath. A hypothetical model for the defect is presented and is supported both by scanning electron microscopy and classic histopathology.

A brief survey of the literature on dentinal dysplasia and calcification of the dentinal papilla is given. It is still debatable whether these two anomalies are variants of a single clinical entity, different stages of a single disease, or two separate pathologic conditions. A case is described and illustrated with roentgenograms. This case has features of both anomalies and, therefore, lends support to the view assuming different degrees of severity of one and the same disease.