Facial Aesthetics following Edgewise and Fränkel Appliance Therapy: The Application of Chernoff Faces

Abstract

This study investigates an application of the graphical technique of multivariate data description, 'Chernoff faces', to orthodontics. This method of pictorial presentation allows the simultaneous examination of several measurements in a single figure. Each variable is represented by a scaled feature of the human face: the size and position of the ears, eyes, eyebrows, nose, and mouth, as well as the face itself, are used to display data in a diagrammatic form. Using this method, the individual post-treatment results of 62 severe Class II division 1 cases treated by either Fränkel or Edgewise appliance therapy were compared. Nine cephalometric variables were chosen, describing the profile and the antero-posterior positions of the lower jaw and teeth, and stylized cartoon faces drawn for each child. These were compared with a control face prepared from untreated children of the same sex and age. Overall, children treated with Fränkel appliances showed a more normal relationship of the lips to Ricketts' aesthetic line and a greater prominence of the lower face. This difference between the two groups was most marked in the soft tissues. In a few cases, however, the appearance of the Edgewise treated children was indistinguishable from that of the controls. It is concluded that Chernoff faces, by portraying several pertinent aspects of data simultaneously, may be a useful adjunct to the presentation of orthodontic findings.