Mild forms of dentinogenesis imperfecta in association with osteogenesis imperfecta as characterized by light and transmission electron microscopy.

Osteogenesis imperfecta (OI) results from various gene mutations leading to defects in type I collagen, which is the major component of both bone and dentin. Yet dentinogenesis imperfecta (DI) is found only in half of the patients with OI. Here we document patients from three families with OI and DI lacking the clinical and radiographic features of DI in permanent teeth. However, light and transmission electron microscopic studies of dentin of deciduous and permanent teeth revealed various changes in the morphology of the dentinal tubules and collagen fibers. In one family, diagnosis of DI preceded that of OI. The grade of severity of dentinal manifestations in patients with OI apparently forms a continuum from normal dentin structure to severe DI, and the marked difficulty in diagnosing mild DI may have led to underestimating its frequency. Furthermore, patients with DI should be carefully examined for the possible presence of OI.