Aims: To describe the craniofacial morphology of a group of patients with Down's syndrome using a cephalometric analysis of the lateral skull radiograph.
Materials and methods: The studied sample consisted of 39 patients with Down's syndrome (24 boys, 15 girls) ranging from 7 to 18 years of age. The computerized cephalometric study of the lateral skull radiograph of each patient was carried out using the method described by Ricketts.
Results: Anterior cross-bite was observed in 38.4% of patients and diminished interincisal angle in 77%. Skeletal parameters matched the clinical norm, indicating mesofacial biotype, i.e., normal maxillomandibular growth. The lower incisors protruded in 84.6% of the individuals studied and were proinclined in 77%; upper incisors were protruded in 77% of the sample. The lower lip protruded in 84.6%. Analysis of craniofacial parameters showed average values within the clinical norm. Analysis of the inner cranium demonstrated normal inclination of the cranial base, while the length of the anterior skull base was diminished in 53.8%.
Conclusions: From the skeletal perspective, patients with Down's syndrome who are in a period of growth demonstrate a reduction of the anterior skull base. From the dentoalveolar perspective, they show protrusion and proinclination of lower incisors, which is related to a tendency to anterior cross-bite and, to a lesser extent, to diminished overbite. Likewise, the lower lip protrusion observed in this study is related to the position of the lower incisor.