The Perception of the Severity of Facial Asymmetry among Laypersons, General Practitioners, Orthodontists, and Maxillofacial Surgeons

Perceptions of mandibular asymmetry among orthodontists, oral and maxillofacial surgeons, and laypersons

Background

Facial asymmetry is one reason orthodontic patients seek treatment. This study assessed the effect of mandibular asymmetry on facial esthetics and treatment needs perceived by laypersons, orthodontists, and maxillofacial surgeons.

Materials and Method

In this descriptive cross-sectional study, the frontal image of a model was captured and symmetrized from the facial midline using Adobe Photoshop software. The mandible was rotated 0°-8° with 1° intervals. Images were presented to 41 laypersons, 39 orthodontists, and 29 surgeons using an online questionnaire. The observers rated each image's esthetics with a 0-100 Visual Analog Scale and determined their treatment need by choosing one of the following three choices: No need for treatment, needs treatment, acceptable, but better to be treated. Analysis of variance for repeated measurements model. The regression method, Kruskal-Wallis analysis, was used for statistical analysis and the level of significance was set as P < 0.05.

Results

The images with 0° and 1° rotation received the highest esthetic rates among all three groups, while the images with 8° rotation were the least attractive ones. Furthermore, the image esthetic ratings significantly affected their treatment need. Mandibular asymmetry diagnosis threshold was 1° for orthodontists, and 3° for both laypersons and surgeons. The treatment need threshold was 5°, 6°, and 7° for surgeons, orthodontists, and laypersons, respectively.

Conclusion

The esthetics of images decreased when mandibular asymmetry increased. Treatment need was also related to increased asymmetry. Orthodontists were the most sensitive group in diagnosis, while surgeons were the most sensitive ones when it came to treatment.

Symmetry and Aesthetics in Dentistry

Animal bodies in general and faces in particular show mirror symmetry with respect to the median-sagittal plane, with exceptions rarely occurring. Bilateral symmetry to the median sagittal plane of the body also evolved very early. From an evolutionary point of view, it should therefore have fundamental advantages, e.g., more effective locomotion and chewing abilities. On the other hand, the recognition of bilaterally symmetric patterns is an important module in our visual perception. In particular, the recognition of faces with different spatial orientations and their identification is strongly related to the recognition of bilateral symmetry. Maxillofacial surgery and Dentistry affect effective masticatory function and perceived symmetry of the lower third of the face. Both disciplines have the ability to eliminate or mitigate asymmetries with respect to form and function. In our review, we will demonstrate symmetric structures from single teeth to the whole face. We will further describe different approaches to quantify cranial, facial and dental asymmetries by using either landmarks or 3D surface models. Severe facial asymmetries are usually caused by malformations such as hemifacial hyperplasia, injury or other diseases such as Noma or head and neck cancer. This could be an important sociobiological reason for a correlation between asymmetry and perceived disfigurement. The aim of our review is to show how facial symmetry and attractiveness are related and in what way dental and facial structures and the symmetry of their shape and color influence aesthetic perception. We will further demonstrate how modern technology can be used to improve symmetry in facial prostheses and maxillofacial surgery.