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Anthropometrics
Key points
• Complete reliance on cephalometric analysis for treatment may lead to suboptimal aesthetic results.
• Beautiful faces of different ethnicities have quite different shapes, but individuals of all ethnicities recognize them as beautiful.
• Faces that conform to the neoclassical canons are moderately attractive, but most attractive faces do not conform to these rules.
• In female faces, femininity is considered attractive, whereas masculinity does not necessarily signal attractiveness in men.
• Surface anthropometric measurements do not always correlate with the shape of underlying bone.
• Although some individual and cross-cultural differences exist, people seem to use similar criteria in their judgments of facial beauty.
History of morphometrics
Attempts to quantify and define facial attractiveness were made as early as 4000 years ago by ancient Egyptians and were further developed in ancient Greek society by applying the Golden Ratio to the study of ideal facial form. In the fifteenth century, these ideas were further developed to formulate the neoclassical canons of facial form by Albrecht Durer, Leonardo Da Vinci, and others. Today these ideas are still supported by many. Moreover, a Marquardt’s Phi Mask—a mesh based on the Golden Ratio—was developed to define facial beauty. However, its usefulness is controversial because the validity of the measurements to define facial beauty is still being debated.
Measurements
Modern morphometric analysis
Modern facial morphometric analytical techniques fall into two categories:
- 1.
Traditional morphometric analysis, based on lengths, widths, angles, ratios, and areas
- 2.
Geometric morphometric analysis, based on shape, using Cartesian landmark coordinates that capture the morphology of the face
Traditional morphometric analysis
Traditional morphometric analysis is based on the analyses of lengths, widths, angles, ratios, and areas. Until recently, all anthropometric analyses in surgery were based on these principles. Recording these measurements is time-consuming and is generally undertaken manually, using various instruments, including tapes, , scales, calipers, and Hertel exophthalmometers. The measurements require great precision and a degree of expertise to record and are open to both intra- and interobserver errors. Manual acquisition of anthropometric data is time-consuming and has limited the collection of large amounts of normative data. Moreover, most of the data relate to measurements of size, which tend to be highly correlated, and as a result, there are few independent variables. Furthermore, these data lack information on shape, which is a key property of interest.
Nevertheless traditional morphometric techniques form the basis of our understanding of the proportions of the human face, and thanks to the pioneering work of Leslie Farkas and others, large amounts of normative data are available. Traditional morphometric analysis is useful in plastic surgery and has revolutionized orthognathic surgery and orthodontics.
Many morphometric techniques are applicable to cosmetic surgery, but three deserve special consideration neoclassical canons, golden ratio and cephalometric analysis.
Neoclassical canons
Horizontal thirds
The face can be divided into thirds: (1) from the hairline to the midbrow, (2) from the midbrow to the nasal floor, and (3) from the nasal floor to the soft tissue menton. ,
Although the horizontal thirds were intended to apply across ethnicities, the proportions tend to be different across races: the middle part is shorter in white individuals and in black men ; and the upper third tends to be longer in black females, in contrast to the shorter upper third compared with the middle and lower thirds in Chinese females. Moreover, the proportions change with aging. Additionally, the lower thirds have more impact on the assessment due to incisor exposure and interlabial gap. This lower part can also be divided into thirds, with the upper one third from the subnasale to the stomion and the lower two thirds from the stomion to the menton, with a 30:70 ratio.
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