Role of facial attractiveness in patients with slight-to-borderline treatment need according to the Aesthetic Component of the Index of Orthodontic Treatment Need as judged by eye tracking.

INTRODUCTION: Previous eye-tracking research has demonstrated that laypersons view the range of dental attractiveness levels differently depending on facial attractiveness levels. How the borderline levels of dental attractiveness are viewed has not been evaluated in the context of facial attractiveness and compared with those with near-ideal esthetics or those in definite need of orthodontic treatment according to the Aesthetic Component of the Index of Orthodontic Treatment Need scale. Our objective was to determine the level of viewers' visual attention in its treatment need categories levels 3 to 7 for persons considered "attractive," "average," or "unattractive."

METHODS: Facial images of persons at 3 facial attractiveness levels were combined with 5 levels of dental attractiveness (dentitions representing Aesthetic Component of the Index of Orthodontic Treatment Need levels 3-7) using imaging software to form 15 composite images. Each image was viewed twice by 66 lay participants using eye tracking. Both the fixation density (number of fixations per facial area) and the fixation duration (length of time for each facial area) were quantified for each image viewed. Repeated-measures analysis of variance was used to determine how fixation density and duration varied among the 6 facial interest areas (chin, ear, eye, mouth, nose, and other).

RESULTS: Viewers demonstrated excellent to good reliability among the 6 interest areas (intraviewer reliability, 0.70-0.96; interviewer reliability, 0.56-0.93). Between Aesthetic Component of the Index of Orthodontic Treatment Need levels 3 and 7, viewers of all facial attractiveness levels showed an increase in attention to the mouth. However, only with the attractive models were significant differences in fixation density and duration found between borderline levels with female viewers. Female viewers paid attention to different areas of the face than did male viewers.

CONCLUSIONS: The importance of dental attractiveness is amplified in facially attractive female models compared with average and unattractive female models between near-ideal and borderline-severe dentally unattractive levels.