While esthetics, function, and stability are essential objectives of orthodontic treatment, the number of adults pursuing treatment due to esthetics has increased during the past decade.12 An increased awareness of facial esthetics has resulted in a growing demand for orthodontic treatment for the correction of perioral esthetic conditions, particularly bimaxillary protrusion.3

Attractive lip proportion is a cornerstone in the esthetics of the lower facial region.456 Several studies assessing the lip position and proportion have been conducted on lateral and frontal photographs.678 Bisson and Grobbelaar9 compared the frontal facial dimensions of models with those of subjects from the general population. Kang et al.10 evaluated differences in esthetic preferences for the lower facial region (subnasale [Sn]-menton [Me]) between Korean and Caucasian subjects. Furthermore, studies have assessed facial esthetic preferences in different age groups and compared them between professionals and nonprofessionals.111213

The eyes, nose, and lips are the preferred targets during the visual perception of faces, because, according to an eye tracking study, the center of the gaze is in the middle of the face near the symmetry plane.14 Meyer-Marcotty et al.15 reported that increased facial asymmetry near the midline of the face resulted in a more negative evaluation of the face in direct face-to-face interactions, suggesting that the midfacial area is crucial during facial perception. In addition, Salehi et al.16 demonstrated the impact of the forehead and neck on facial esthetics. Currently, the parameters determining the assessment of facial attractiveness remain controversial.

Row and Rhu17 evaluated the facial esthetics of Korean beauty pageant contestants in the late 80s using a cephalometric study. However, beauty standards change over time and are affected by concurrent fashion trends, media, and social and economical-security environments.18192021 In addition, they also interact with ethnicity, local customs, and culture2223; therefore, an ongoing assessment of facial esthetic standards is necessary.

Despite the growing influence of the Koreans in global media, no recent evaluation of Korean esthetic standards has been performed. Therefore, the aim of this study was to evaluate the facial dimensions of young adult women with a preferred facial appearance and compare the results with those for women from the general population.

The sample comprised standardized frontal and lateral facial photographs of 46 young adult women with a preferred facial appearance who participated in the final round of the Miss Korea Pageant in 2012 (Miss Korea group) and 44 young adult women from Wonkwang Health Science University, Korea (control group). The participants were aged between 18.8 and 32.2 years (mean, 25.3 ± 4.7 years). They provided consent to participate in this study, which was approved by the institutional review board of The Catholic University of Korea (KC140ISE0057).

The inclusion criteria for the control group were females with a mesocephalic face type, straight profile, balanced facial appearance, no history of plastic or maxillofacial surgery or orthodontic treatment, absence of mentalis hyperactivity, and an interlabial gap of less than 1 mm. The surgical history was not available for the Miss Korea group.

Photographs were obtained in the natural head position, with standardized settings using a digital singlelens reflex camera (EOS 450D; Canon, Tokyo, Japan) with a shutter speed of 1/60, relative aperture (f/5.6), and a distance of 1 m from the volunteer under good illumination conditions. Moreover, to correct for any possible variations in image size, all linear and area dimensions were expressed as a ratio of the interendocanthal distance on the frontal image, which was assigned a nominal value of 10 units according to the method of Bisson and Grobbelaar.9 Then, the scale was transferred to the lateral view through a variable (total facial height) measured on both images.

Twenty-five linear dimensions, nine angles, and three areas were measured on the frontal and lateral images using Digimizer 4.2.2 (MediCalc Software, Ostend, Belgium; Figure 1 and Table 1). In addition, four ratios were calculated as follows: trichion (Tr)-nasion (N)/total facial height (TFH; Tr-Me), N-Sn/TFH, Sn-Me/TFH, and facial width (tragus [T]_Rt-T_Lt)/TFH.

The photographs of 10 participants were redigitized and measured at least 2 weeks after the first evaluation. The intraclass correlation coefficient (ICC) was used to assess the reliability of measurements. All measurements showed an ICC of > 0.9.

Comparisons of paired variables showed no significant differences between the right and left sides within both groups (Table 2). Therefore, for each of those variables, the mean of the values obtained for either side was used for comparison between groups.

Multivariate analysis showed a significant main effect of group (p < 0.001) on the comparison. Univariate analysis showed that the Miss Korea group had a significantly greater facial height (N-Me), TFH (Tr-Me), facial width (T_Rt-T_Lt), facial depth (T-TVL), and Tr-N/TFH and smaller Sn-Me/TFH and facial width/TFH ratios compared with those in the control group (Table 3).

Furthermore, the forehead height was greater in the Miss Korea group than in the control group, although there were no differences in the amount of protrusion of the forehead from the TVL and frontonasal angle between the two groups. The intercanthal and interpupillary widths were smaller in the control group than in the Miss Korea group (Table 3).

The nasal width was not significantly different between groups; however, the nasal height and length were greater in the Miss Korea group than in the control group, whereas the amount of nasal protrusion and nasal angle were significantly smaller (Table 3).

The mouth width, upper vermilion height, and Cupid bow angle were greater in the Miss Korea group than in the control group, while the amount of lower lip protrusion (UL-TVL) was smaller (Table 3).

The lower lip and chin height (Stmi-Me), lower vermilion height and angle, lower and total vermillion areas, and the amount of lower lip (LL-TVL) and chin (Pog-TVL) retrusion were greater, while the labiomental angle was smaller in the Miss Korea group than in the control group. The former also showed a smaller cervical angle and a deeper cervical point (cervical-TVL) compared with the latter (Table 3).

Facial appearance plays an essential psychosocial role, particularly in terms of self-esteem. An attractive face is associated with good health, fitness, social skills, and prosperity; therefore, it may be considered a key to a successful life.24 However, esthetic standards are subjective and usually influenced by the media and fashion trends, with a diverging gap between the media-defined ideals and reality.25

Norms for facial dimensions and esthetic preferences have been evaluated in several populations,2627 but there was no consensus among these studies. With fast-developing globalization ideologies, these trends are differently affected by different cultures. Currently, many patients are seeking medical help to improve their facial esthetics in response to media figures. Therefore, this study was designed to clarify the current differences in facial esthetics between common young adult women and the Miss Korea group through an evaluation of both frontal and lateral photographs.

Our results showed that the Miss Korea group had longer, wider, and deeper faces compared with the control group. Furthermore, the lower facial ratio (SN-Me/TFH) was smaller and the upper facial ratio and width (Tr-N/TFH and T_Rt-L_Lt) were greater for the women in the Miss Korea group, resulting in a more downward tapering of their faces than those of the general population group. Meanwhile, the faces of women in the control group were flatter and more square. These findings were somewhat contradictory to the findings of Ferrario et al.,27 who reported shorter faces in the beauty group than in the control group, with no significant differences in the facial width and depth at the tragus between the two groups. They also reported a greater lower facial width in the beauty group.27 However, the upper facial height was greater in the beauty group than in the control group, with no significant differences in the lower facial height between the two groups; these findings were consistent with ours.

Moreover, the Miss Korea group showed a greater nasal height and smaller nasal angle compared with the control group. In contrast, Ferrario et al.27 showed a smaller nasal height in the beauty group and no significant difference in the nasal angle.

Several landmarks and dimension defined in the study by Ferrario et al.27 were modified from conventional medical anthropometry, although they identified the landmarks directly on the subject's faces using palpation before imaging. On the other hand, in our study, the landmarks and definitions were modified because the digitization process was performed after imaging, making it impossible to identify some landmarks such as the gonion through palpation. Despite this disadvantage, the digitization of images is a faster and more comfortable process with an easy learning curve.

The Miss Korea group had a greater eye width compared with those in the control group. This finding was consistent with that of Sforza et al.,28 who reported greater eye widths in beauty groups than in normal groups of both men and women.

Although the lower lip and chin height was significantly greater in the Miss Korea group, while the upper lip height was not significantly different between groups, the lower third of the face can be divided into a third for the upper lip and two-thirds for the lower lip and chin in both groups. A previous study showed this ratio to be 30% and 70%, respectively, and considered it to be a historically lasting canon.29 However, this difference, in addition to racial factors, could be due to differences in the landmarks used to define the lower border of the chin (i.e., menton in our study and gnathion in the previous study).

The necks of the women in the Miss Korea group were farther from the TVL and made a smaller angle with the chin compared with those of the control group. This may partially support the perception of Salehi et al.,16 who showed that the anteroposterior position of the neck affects the esthetics of the sagittal jaw relationship. They reported that patients with Class I malocclusion showed the best esthetics with normal or retruded necks, while those with Class III malocclusion showed the best esthetics with protruded necks.

A previous study including Miss Korea contestants in the late 80s demonstrated that they had a greater nasolabial angle (105.0°) compared with women from the general Korean population and Caucasian women.17 They also had a less prominent nose, more prominent lips, and a deeper sulcus.

Interestingly, our study showed that a less prominent nose and an accentuated mentolabial sulcus are considered to be signs of beauty in the Korean society. However, the nasolabial angle in the Miss Korea group (98.9°) in our study was not significantly different from that in the control group. In addition, the lips of women in the Miss Korea group were more retruded (UL-TVL and LL-TVL) than those of the control group and those observed in the previous study.17 This may be considered a manifestation of the increasing effects of the Western mass media on the perception of beauty in the current Korean society.

Our results support the notion of a continuous change in esthetic standards over time. It may be interesting to conduct a lateral cephalometric analysis of a current beauty pageant sample to assess the changes in skeletal traits. However, similar to the situation in a previous study,28 the women in the Miss Korea group preferred not to disclose their surgical history. Not only did they refuse to undergo lateral cephalometry, they also declined to answer questions about previous plastic or orthognathic surgeries. Nonetheless, this was not significant because they represented beauty standards of the current Korean society, even if the surgical correction was in the interendocanthal width which affects all the other variables. Therefore, whether they met the beauty standards naturally or through surgical enhancement was inconsequential.

Kang et al.10 compared facial dimensions measured on frontal views between models and women from the general population and showed that the models had fuller lower and thinner upper vermilion areas. Our study also demonstrated that the lower lip vermilion height, angle, and area were greater in the Miss Korea group than in the control group. However, there were no significant differences in the upper lip vermilion angle and area between the two groups. Moreover, as opposed to the findings of Kang et al.,10 there was no significant difference between groups in the central bow angle, while the Miss Korea group showed a greater Cupid bow angle.

Generally, full and rounded lips are considered more attractive and give a more youthful appearance.3031 Park and Hwang6 reported an increase in the nasolabial angle and philtrum length and a decrease in the vermilion length and lip width after anterior segment osteotomy. Cha et al.32 suggested that the values in some post-treatment records for the general population approached the esthetic standards for models. Therefore, it is important to pay extra attention to the frontal facial features, particularly those in the lower facial region, while planning orthodontic or orthognathic treatment.

In our study, the Miss Korea and control groups wore no make-up to allow more accurate evaluation of the landmarks. In addition, evaluations were made by measuring linear dimensions divided by the interendocanthal width to provide standardized results.9 It may be important to consider proportions as well as absolute values when comparing different groups. In addition, differences in linear dimensions, particularly vertical dimensions, may be attributed to differences in body height. However, this aspect was not considered in this study. However, a recent study reported no significant correlations between body height and orofacial measurements, including facial and lip heights and ratios, in women.33

Further studies using three-dimensional stereophotogrammetry are recommended to evaluate differences in esthetics between individuals with a preferred facial appearance and those from the general population to provide more detailed esthetic norms. Furthermore, a comparison of facial esthetics between different ethnic groups may shed light on cultural differences between societies.

These findings suggest the necessity to consider the latest trends in facial esthetics during diagnosis and treatment planning for young adult women with dentofacial abnormalities.