The interaction between soft tissues and the sagittal development of the dentition and the face

The purpose of this study was to investigate whether there are relationships between the cross-sectional surface area (CSSA) of the lips and the sagittal structure of the skeletal parts of the face and the dentition in the midsagittal plane and whether the sagittal structure of the face and the dentition is related to the class of malocclusion. The CSSA of the upper and lower lip was measured with a planimeter on the lateral cephalograms of 156 patients before their orthodontic treatment with a closed lip relation in rest. They were divided into 18 groups according to their age, sex, and Angle classification. The Quick Ceph program (Orthodontic Processing, Chula Vista, Calif.) was used to digitize and analyze 23 dental and skeletal parameters. The parameters were tested by an analysis variance to show differences between the three classes of malocclusion. The regression analysis was used to look for relations between the CSSA and the skeletal or dental parameters. It appeared that the mean and the variance of the lip line and the inclination and the sagittal position of the incisors are significantly different between the three classes of malocclusion ( p p p p p p p