Dentinal dysplasia Dentinal dysplasia is an inherited condition affecting both dentitions. It is divided into two types: Type I (radicular dentinal dysplasia) and Type II (coronal dentinal dysplasia). It occurs less frequently than dentinogenesis imperfecta. Clinical features Type I is the more frequent type. Teeth erupt normally with no obvious abnormality but rapidly develop mobility resulting from limited root support. In type II, the deciduous teeth are similar to those in dentinogenesis imperfecta, whereas the permanent teeth appear normal. Radiological signs In Type I, all the teeth, except the canines, have extremely short roots. The roots are conical or blunted. There is pulpal obliteration and the inferior aspects of the crown exhibit linear crescent-shaped radiolucent lines. Periapical radiolucencies are commonly seen associated with non-carious teeth in Type I dentinal dysplasia. In Type II dentinal dysplasia, obliteration of the pulp occurs post eruption in the deciduous dentition. In the permanent dentition, there is alteration in the configuration of the pulp resulting in enlarged pulp chambers extending well down into the root. The pulp contains multiple calcifications. Ref: Interpreting Dental Radiographs by Keith Horner, Jon Rout and Vivian E Rushton