Section of Dentistry, Department of Surgery, The Aga Khan University Hospital, Karachi, Pakistan.
J Esthet Restor Dent. 2024 Nov;36(11):1566-1573. doi: 10.1111/jerd.13298. Epub 2024 Aug 16.
BACKGROUND/OBJECTIVE: A contemporary concept states that dental midline deviation towards the direction of facial flow line (FFL) can mask the compromised smile esthetics. This study aimed to identify a range of midline deviations that can be perceived towards or away from the FFL influencing smile esthetics.
A cross-sectional study was conducted using a frontal smile photograph of an adult female. The photograph was altered on Adobe Photoshop software into six different photographs by deviating the dental midlines towards and away from the FFL. A constant deviation of chin towards the left side was incorporated in all the photographs. Forty-three laypersons (LP) and dental professionals (DPs) evaluated those photographs. Independent t-test was used to compare the perception of dental midline deviation between LP and DPs. Simple linear regression was run to identify the factors associated with the scoring.
A statistically significant difference was observed for picture two with 4 mm towards FFL in the perception of midline deviation between LP and DPs. LP could not perceive the midline deviations up to 4 mm while DPs were able to perceive deviations above 2 mm. The greater the age the better the scores were and female raters had a greater inclination towards poor scores.
From 2 to 4 mm of midline deviation towards the FFL can be tolerated by LP and DPs.
These findings underscore the importance of considering facial symmetry in orthodontic and cosmetic dental treatments to optimize smile esthetics.
背景/目的：一种现代观念认为，牙齿中线向面部流线方向（FFL）的偏差可能会掩盖受损的微笑美学。本研究旨在确定可感知的中线向 FFL 方向或远离 FFL 方向的偏差范围，这些偏差会影响微笑美学。
本研究采用横断面研究，使用成年女性的正面微笑照片。使用 Adobe Photoshop 软件对照片进行修改，通过使牙齿中线向 FFL 方向和远离 FFL 方向的方式生成六张不同的照片。所有照片中均包含下巴向左侧恒定的偏移。 43 名非专业人士（LP）和口腔专业人士（DP）评估了这些照片。使用独立 t 检验比较 LP 和 DPs 对牙齿中线偏差的感知。运行简单线性回归以确定与评分相关的因素。
在 LP 和 DPs 对中线偏差感知方面，对于向 FFL 方向有 4mm 偏差的图片二，观察到统计学上的显著差异。LP 无法感知中线偏差达到 4mm，而 DPs 能够感知超过 2mm 的偏差。年龄越大，评分越高，女性评定者更倾向于获得较差的评分。
LP 和 DPs 可以容忍中线向 FFL 方向 2 至 4mm 的偏差。
这些发现强调了在正畸和美容牙科治疗中考虑面部对称性的重要性，以优化微笑美学。
