Selecting subjects with high craniofacial shape homogeneity for clinical trials.

Introduction: Morphologic homogeneity is desirable in sample selection of clinical studies that evaluate methods of treating craniofacial discrepancies in orthodontics. The purposes of this study were to assess sample selection criteria commonly used in the orthodontic literature regarding their effectiveness in achieving morphologic homogeneity, and to propose a method that can guarantee selection of a homogeneous sample, for which the degree of homogeneity and the average skeletal pattern can be specified a priori.

Methods: Pretreatment lateral cephalograms from 170 consecutive patients (82 boys, 88 girls) aged 7 to 17 years were used.