The influence of the nasolabial angle on percieved facial aesthetics- a study using a 3D facial image and image manipulation software.

El-Habbash, Salwa (2023). The influence of the nasolabial angle on percieved facial aesthetics- a study using a 3D facial image and image manipulation software. University of Birmingham. M.Sc.

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Abstract

Objectives: Orthodontists aims to achieve a Class I occlusion, without “harming” the facial profile. Movement of teeth and facial bones can result in changes of soft tissues including the nasolabial angle (NLA). Many studies assess the perception of the NLA using two-dimensional (2D) profile images, these may alter aesthetic judgement as three-dimensional (3D) images are closer to real-life.
Aims: To determine which NLA, from 70° to 110°, was rated as most attractive by laypeople and clinicians and if this was impacted by the type of image viewed i.e., 2D profile silhouettes, 3D textured and 3D grey non-textured images.
Methodology: Using a 3D facial image and image manipulation software, five 3D grey non-textured images were produced with NLA’s of 70°, 80°, 90°, 100° and 110°. Using software from the gaming and film industry, the same male or female textured image was “wrapped” onto each of these images, producing ten further 3D images of the same individual with the five different NLA’s. Five 2D profile silhouettes were generated from the 3D images resulting in 20 images which were embedded in a PowerPoint presentation. Seventy-two laypeople and fifty clinicians were recruited to rate the facial attractiveness of the images using a 7-point Likert scale.
Results: There was a statistically significant difference in the facial attractiveness scores across the NLA’s being assessed (p=0.001) in both groups. Two-dimensional profile silhouettes underestimated the unattractiveness of 100° and 110° NLA’s compared with 3D images in both groups (p<0.05).
Comparing 2D profile silhouettes and 3D grey non-textured images there was no statistical difference in attractiveness scores given by clinicians between NLA’s of 70°, 80° and 90°. There was no statistical difference in attractiveness scores by laypeople for the 80° NLA, however the 3D grey non-textured images scored significantly lower than the 2D profile images with NLA’s of 90°, 100° and 110° but significantly higher for the 70° NLA (p<0.05).
Overall, laypeople rated images more unattractive than clinicians, however clinicians were more likely to seek treatment. Both groups rated 3D grey non-textured images as less attractive than 2D facial profile silhouette images with NLA’s of 100° and 110° (p<0.05). Both groups preferred rating 3D textured images overall.
Conclusion: The null hypothesis was rejected as there was a statistically significant difference (p<0.05) in facial attractiveness rating score between clinicians and laypeople assessing the NLA’s on the images and in the rating of the NLA between 2D facial profile silhouette images and 3D grey non-textured images.

Type of Work:

Thesis (Masters by Research > M.Sc.)

Award Type:

Masters by Research > M.Sc.

Supervisor(s):