The Differences of Perception of Asymmetry on Chin and Lip in Facial Asymmetry Patients Rated by Laypersons and Orthodontists

Abstract

Background: The perception of facial asymmetry plays a critical role in the diagnosis and treatment planning in orthodontics. Objective: This study aimed to evaluate the perception of chin deviation and lip canting and to compare the differences in perception between laypersons and orthodontists. Materials and methods: Fifty-five new patients presenting with facial asymmetry were examined. Subjects were categorized into four groups based on the severity of chin deviation and lip canting. Three-dimensional (3D) facial images and corresponding mirror images were generated. A total of twenty-six laypersons and orthodontists were asked to compare the original and mirror images, after which they categorized the asymmetry into three levels: normal, acceptable, and unacceptable. Results: For chin deviations of 0–2 mm, laypersons generally perceived the asymmetry as normal, while orthodontists classified it as either normal or acceptable. In cases of chin deviation exceeding 2–4 mm, laypersons tended to rate it as acceptable, whereas orthodontists judged it as unacceptable. When the chin deviation exceeded 4 mm, both groups perceived it as unacceptable. Regarding lip canting of 0–1 mm, both laypersons and orthodontists classified it as normal. When lip canting increased to over 1–2 mm, laypersons still considered it normal, while orthodontists classified it as acceptable. Lip canting exceeding 2–3 mm was generally perceived by both groups as acceptable, and canting greater than 3 mm was considered unacceptable by both laypersons and orthodontists. Conclusion: Orthodontists exhibited greater sensitivity than laypersons in perceiving both chin deviation and lip canting.