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Factors Contributing to Facial Asymmetry in Identical Twins
Mengyuan T. Liu, BS
Rodrigo A. Iglesias, MBA, MS
Kelsey Larson, MD
Bahman Guyuron, MD, FACS
Case Western Reserve University
2013-02-11
Presenter: Mengyuan T Liu
Affidavit:
I certify that the material proposed for presentation in this abstract has not been published in any scientific journal or previously presented at a major meeting. The above work represents 80% of the original work of the presenter.
Director Name: Bahman Guyuron
Author Category: Medical Student
Presentation Category: Clinical
Abstract Category: Aesthetics
Background: This study examines the potential role of environmental factors on facial asymmetry between identical twins.
Methods: Identical male and female twins independently completed a comprehensive questionnaire on their medical and personal history, and posed for digital facial photography from several different angles. From these photographs, eight facial features were measured using Adobe Photoshop. These facial features were then analyzed against survey responses between twins through multivariate regressions.
Results: A total of 212 pairs of identical twins (n=424, 100 men, 324 women, mean age 43.8+16.8 years) were recruited. Twins who slept primarily prone had greater nasal midline deviation (p=0.047). Smoking was associated with canting of the plane of occlusion (p=0.049) and upper eyelid ptosis (p=0.023). Headaches were associated with nasal midline deviation (p=0.024) and ear length asymmetry (p=0.001). The twins who slept fewer hours had more significant nasal midline deviation (P<0.001) and greater oral commissure asymmetry (p<0.001). Twins with the longer duration of stress had lesser nasal tip projection (p=0.019). Tooth extractions were significantly associated with canting of the plane of occlusion (p=0.043), while use of dentures was associated with nasal midline deviation (p=0.032) and oral commissure asymmetry (p=0.007). Twins who wore glasses had greater occlusion canting (p=0.007) and more nasal tip projection (p=0.013). Twins who were never married also had more significant nasal deviation (p<0.001) and oral commissure asymmetry (p<0.001).
Conclusions: Exogenous factors such as dentures, sleeping on a prone position, tooth extractions, smoking, never having been married, decreased sleep, glasses, and headaches are associated with facial asymmetry.
