Dipartimento di Scienze Biomediche per la Salute, Università degli Studi di Milano, via Mangiagalli 31, 20133, Milan, Italy.
Dipartimento di Elettronica, Informazione e Bioingegneria (DEIB), Politecnico di Milano, Milan, Italy.
Aesthetic Plast Surg. 2014 Feb;38(1):236-241. doi: 10.1007/s00266-013-0227-9. Epub 2013 Oct 19.
With increasing age, the smile becomes elongated and less appealing. Currently, several methods are proposed for analysis of lip morphology including lateral cephalograms, profile and frontal photographs, video images, and three-dimensional systems. Despite several descriptions of morphologic and histologic age-related changes in the literature, no scientific well-supported model of the labial aging process is reported.
For this study, 33 healthy volunteers were selected and divided into two groups according to age: a youthful group (ages 21-34 years) and an aged group (ages 45-65 years). Their dental and labial stone casts were obtained, digitized, and virtually reproduced using a computerized electromechanical digitizer and applying nonuniform rational B-spline geometry. To obtain a synthetic parameter describing local surface deformation, average curvature and curvature variability indexes were computed and compared.
No significant age- or sex-related differences in the average curvature were detected. In contrast, the curvature variability was significantly greater in the young than in the aged subjects.
The labial arch surface remains macroscopically constant between the third and the sixth decades of life, but with local modifications that influence the standard deviation of its curvature. A high standard deviation described the protruding labial appearance of the young subjects, whereas a reduced one described the flat lips of the aged subjects.
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随着年龄的增长，微笑会变得更长，吸引力也会降低。目前，有几种方法被提出用于分析唇形态，包括侧头颅侧位片、侧貌照片、正面照片、视频图像和三维系统。尽管文献中有关于唇形态和组织学与年龄相关的变化的描述，但没有科学支持的唇老化过程的模型。
本研究选择了 33 名健康志愿者，并根据年龄分为两组：年轻组（年龄 21-34 岁）和老年组（年龄 45-65 岁）。他们的牙齿和唇石模型被获得、数字化，并使用计算机机电数字化仪和非均匀有理 B 样条几何进行虚拟再现。为了获得描述局部表面变形的综合参数，计算并比较了平均曲率和曲率变异性指数。
未检测到平均曲率与年龄或性别相关的显著差异。相比之下，年轻组的曲率变异性明显大于老年组。
唇弓表面在第三和第六十年之间保持宏观上的恒定，但存在影响其曲率标准差的局部变化。高标准差描述了年轻受试者突出的唇外观，而低标准差描述了老年受试者平坦的唇。
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