Cognition of alterations on a facial form corrected by orthognathic surgery.

The purpose of this study was to investigate observer's cognition of alterations on a facial form corrected by orthognathic surgery. Subjects were twenty undergraduate students at a women's college, who had no technical training in dentistry before. The subjects ranged in age from 19 to 22. The computerized analytic system was used for the fixation points analysis of eye movement. Two test cards (55 x 65cm) were used as stimuli; one test card bearing two frontal facial photographs of a patient, preoperative and postoperative, the other test card bearing two lateral facial photographs of the same patient likewise. The patient showed asymmetrical mandibular prognathism, corrected by Obwegeser-Dal Pont osteotomy and Le Fort I osteotomy. Each subject's eye movement was analyzed for 10 seconds during presentation of each stimulus. Fixation points, characteristic points and saccadic eye movements were used as indices. Subjects' introspective comments showed that 70 percent (same person-a brother group) of the subjects recognized two faces as resembling. From eye movement analysis, it was identified that the same person-a brother group searched out precisely at areas which were corrected by orthognathic surgery. This group pointed out lips or chin as differences of facial features by the introspective comments. It was suggested that these subjects comparatively make much more of impression than different facial features themselves. It was clarified that simultaneous repositioning of maxilla and mandible maintained impression of a patient's face. In conclusion, if a dentofacial deformity of a patient's face is altered by orthognathic surgery, the similarity of the face can be maintained after the surgery.