Two forms of Dentinal dysplasia (rare autosomal dominant disease) are described below.
In type I (rootless teeth) thepermanent teeth have normal crowns associated with roots composed of dysplastic dentinecontaining numerous calcified, spherical bodies. The pulp chamber and root canals are largelyobliterated and the roots are usually very stunted. The abnormality is due to a defect in Hertwig’sroot sheath which fragments and is incorporated into the dental papilla where it induces formationof fused globular masses of abnormal dentine. The first sign may be premature exfoliation eitherspontaneously or with minor trauma.
Type II dentinal dysplasia (coronal dentine dysplasia) may not be a distinct entity. It has beenlinked to the same area on chromosome 4 as dentinogenesis imperfecta type II. The appearances inthe primary dentition are the same but the permanent teeth are of normal colour and root length.