The gnathic and dental manifestations are distinctive and may lead to the initial diagnosis. The patients often have a narrow, high-arched palate, and there is an increased prevalence of cleft palate. Prolonged retention of deciduous teeth and delay or complete failure of eruption of permanent teeth are characteristic features. There may be abnormal spacing in the mandibular . incisor area because of widening of the alveolar bone. On review of dental radiographs, the most dramatic finding is the presence of numerous unerupted permanent and supernumerary teeth, many of which frequently exhibit distorted crown and root shapes ( fig.14-7) the number of supernumerary teeth can be impressive, with reports of some patients demonstrating more than 60 such teeth.