Characteristics of Down syndrome subjects in a Saudi sample

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

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.

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.

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.