Characteristics of Down syndrome subjects in a Saudi sample.

Objective: To compare the cephalometric characteristics of Down syndrome (DS) subjects with those of normal subjects.

Materials And Methods: Cephalometric radiographs of 60 Saudi DS subjects and 60 controls with specific inclusion criteria were used. Descriptive statistics were used to describe the quantitative and categorical variables, and the Student's t-test for two independent samples was used to compare the mean values of quantitative variables.

Results: SBa and SN were higher in controls than in DS subjects, whereas the NSBa was significantly higher in DS subjects than in controls. SNA, Co-A, ANB, and A-Na perp of controls were higher than the DS subjects. However, SN-MP, PP-MP, ANS-Me/N-Me, Y-axis, and Ar-Go-Me of the DS subjects were higher than those of the controls. In addition, U1-NA, U1-NA mm, L1-NB, and L1-NB mm of the DS subjects were also higher than the controls with a more acute U1-L1 angle in DS. NLA was larger in controls than in DS, whereas LL-E and UL-E of the DS subjects were higher than the controls.

Conclusions: Differences between DS subjects and controls can be found when examining cephalometric radiographs. Anterior and posterior cranial base lengths are shorter with a backward inclination of the posterior cranial base in DS subjects. DS subjects present with a retrognathic maxilla and shorter effective length, with an increased LFH and a hyperdivergent mandible. Bimaxillary dental protrusion can also be expected in DS subjects with prominent lips and a reduced nasolabial angle.