Original article
Contribution of malocclusion and female facial attractiveness to smile esthetics evaluated by eye tracking

https://doi.org/10.1016/j.ajodo.2014.12.016Get rights and content

Highlights

  • Eye tracking provides an objective method to evaluate what people view.

  • Seventy-six viewers underwent eye tracking sessions while viewing facial photographs.

  • Data were collected for the first location, frequency, and duration of the viewers' gaze.

  • For number and duration of fixations, eyes were the most salient feature and the mouth the second.

  • As dental attractiveness decreased, visual attention on the mouth increased.

Introduction

There is disagreement in the literature concerning the importance of the mouth in overall facial attractiveness. Eye tracking provides an objective method to evaluate what people see. The objective of this study was to determine whether dental and facial attractiveness alters viewers' visual attention in terms of which area of the face (eyes, nose, mouth, chin, ears, or other) is viewed first, viewed the greatest number of times, and viewed for the greatest total time (duration) using eye tracking.

Methods

Seventy-six viewers underwent 1 eye tracking session. Of these, 53 were white (49% female, 51% male). Their ages ranged from 18 to 29 years, with a mean of 19.8 years, and none were dental professionals. After being positioned and calibrated, they were shown 24 unique female composite images, each image shown twice for reliability. These images reflected a repaired unilateral cleft lip or 3 grades of dental attractiveness similar to those of grades 1 (near ideal), 7 (borderline treatment need), and 10 (definite treatment need) as assessed in the aesthetic component of the Index of Orthodontic Treatment Need (AC-IOTN). The images were then embedded in faces of 3 levels of attractiveness: attractive, average, and unattractive. During viewing, data were collected for the first location, frequency, and duration of each viewer's gaze.

Results

Observer reliability ranged from 0.58 to 0.92 (intraclass correlation coefficients) but was less than 0.07 (interrater) for the chin, which was eliminated from the study. Likewise, reliability for the area of first fixation was kappa less than 0.10 for both intrarater and interrater reliabilities; the area of first fixation was also removed from the data analysis. Repeated-measures analysis of variance showed a significant effect (P <0.001) for level of attractiveness by malocclusion by area of the face. For both number of fixations and duration of fixations, the eyes overwhelmingly were most salient, with the mouth receiving the second most visual attention. At times, the mouth and the eyes were statistically indistinguishable in viewers' gazes of fixation and duration. As the dental attractiveness decreased, the visual attention increased on the mouth, approaching that of the eyes. AC-IOTN grade 10 gained the most attention, followed by both AC-IOTN grade 7 and the cleft. AC-IOTN grade 1 received the least amount of visual attention. Also, lower dental attractiveness (AC-IOTN 7 and AC-IOTN 10) received more visual attention as facial attractiveness increased.

Conclusions

Eye tracking indicates that dental attractiveness can alter the level of visual attention depending on the female models' facial attractiveness when viewed by laypersons.

Section snippets

Material and methods

The institutional review board at Ohio State University approved the study. Preliminary steps were necessary to create the composite images with varying levels of facial and dental attractiveness used in this study. This allowed us to pair truly comparable and reliably rated faces and dentitions rather than searching for naturally occurring combinations and having to accept compromises.

Facial images were obtained by seeking subjects (18-30 years of age) on an availability basis on our campus

Results

Seventy-eight viewers entered the study, and 76 finished the study. Two viewers were disqualified because of difficulty in calibrating the eye tracker and not being able to keep it calibrated throughout the eye-tracking session. Only white viewers (n = 53) were used in the analysis to remove the known racial and ethnic variabilities. Of these viewers, 49% (26) were female, and 51% (27) were male. Their ages ranged from 18 to 29 years, with a mean of 19.8 years.

Intrarater reliability differed

Discussion

The aim of this study was to evaluate the effect of levels of dental and facial attractiveness on viewers' visual attention using objective data from eye tracking. To do this effectively, the study was conducted with only white female facial images and white viewers. The facial images projected a consistent emotion. The randomly presented “X” before each image served to minimize visual cuing of the observers. All methodologic approaches were supported by the previously cited literature and

Conclusions

  • 1.

    Eye tracking is a reliable and objective method for evaluating the visual attention paid to facial features.

  • 2.

    The eyes are the most salient facial feature, followed by the mouth, for both duration and fixations.

  • 3.

    The grade of dental attractiveness affected the way viewers looked at faces, and the background level of facial attractiveness was an independent factor modifying this behavior.

  • 4.

    An isolated (no nasal involvement) repaired unilateral cleft lip with attractive teeth has less effect on the

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    All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest, and none were reported.

    Financial support provided by the Dental Master's Thesis Award Program sponsored by Delta Dental Foundation, philanthropic affiliate of Delta Dental of Michigan, Ohio, and Indiana.

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