The facial soft tissue profile of the southern Chinese: prosthodontic considerations

Inter-Ethnic/Racial Facial Variations: A Systematic Review and Bayesian Meta-Analysis of Photogrammetric Studies

BACKGROUND

Numerous facial photogrammetric studies have been published around the world. We aimed to critically review these studies so as to establish population norms for various angular and linear facial measurements; and to determine inter-ethnic/racial facial variations.

METHODS AND FINDINGS

A comprehensive and systematic search of PubMed, ISI Web of Science, Embase, and Scopus was conducted to identify facial photogrammetric studies published before December, 2014. Subjects of eligible studies were either Africans, Asians or Caucasians. A Bayesian hierarchical random effects model was developed to estimate posterior means and 95% credible intervals (CrI) for each measurement by ethnicity/race. Linear contrasts were constructed to explore inter-ethnic/racial facial variations. We identified 38 eligible studies reporting 11 angular and 18 linear facial measurements. Risk of bias of the studies ranged from 0.06 to 0.66. At the significance level of 0.05, African males were found to have smaller nasofrontal angle (posterior mean difference: 8.1°, 95% CrI: 2.2°-13.5°) compared to Caucasian males and larger nasofacial angle (7.4°, 0.1°-13.2°) compared to Asian males. Nasolabial angle was more obtuse in Caucasian females than in African (17.4°, 0.2°-35.3°) and Asian (9.1°, 0.4°-17.3°) females. Additional inter-ethnic/racial variations were revealed when the level of statistical significance was set at 0.10.

CONCLUSIONS

A comprehensive database for angular and linear facial measurements was established from existing studies using the statistical model and inter-ethnic/racial variations of facial features were observed. The results have implications for clinical practice and highlight the need and value for high quality photogrammetric studies.

Craniofacial characteristics related to daytime sleepiness screened by the paediatric daytime sleepiness scale

The present cross-sectional study aimed to assess daytime sleepiness in Chinese adolescents using the Paediatric Daytime Sleepiness Scale (PDSS) and to identify associations between PDSS answers and craniofacial characteristics. A group of 265 Chinese adolescents aged 11-17 years self-completed the PDSS, and their extra- and intra-oral craniofacial characteristics were recorded. Among the participants, 59.7% (157) experienced one or more daytime sleepiness events. No significant associations were found between total PDSS scores and the craniofacial parameters, but when PDSS answers were assessed at the item level, several craniofacial characteristics were found to be positively associated with daytime sleepiness, such as hypertrophic tonsils (P = 0.05), a relatively large tongue (P < 0.01), a bilateral Class II molar relationship (P < 0.05) and increased overjet (P < 0.05). A short lower face (P < 0.01) and a convex profile (P < 0.01) were found to be negatively associated with daytime sleepiness. Daytime sleepiness is commonly reported among Chinese adolescents seeking orthodontic treatment and there are potential associations between the condition and craniofacial characteristics. An assessment of daytime sleepiness is recommended to orthodontists in young patients presenting with hypertrophic tonsils, relative large tongues and Class II tendency malocclusions, and appropriate medical referrals should also be considered.

Analysis of dynamic smile and upper lip curvature in young Chinese

During smile evaluation and anterior esthetic construction, the anatomic and racial variations should be considered in order to achieve better matching results. The aims of this study were to validate an objective method for recording spontaneous smile process and to categorize the smile and upper lip curvature of Chinese Han-nationality youth. One hundred and eighty-eight Chinese Han-nationality youths (88 males and 100 females) ranged from 20 to 35 years of age were selected. Spontaneous smiles were elicited by watching comical movies and the dynamics of the spontaneous smile were captured continuously with a digital video camera. All subjects' smiles were categorized into three types: commissure, cuspid and gummy smile based on video editing software and final images. Subjects' upper lip curvatures were also measured and divided into three groups: upward, straight and downward. Reliability analysis was conducted to obtain intra-rater reliabilities on twice measurements. The Pearson Chi-square test was used to compare differences for each parameters (α=0.05). In smile classification, 60.6% commissure smile, 33.5% cuspid smile and 5.9% gummy smile were obtained. In upper lip measurement, 26.1% upward, 39.9% straight and 34.0% downward upper lip curvature were determined. The commissure smile group showed statistically significant higher percentage of straight (46.5%) and upward (40.4%) in upper lip curvatures (P<0.05), while cuspid smile group (65.1%) and gummy smile group (72.7%) showed statistically significant higher frequency in downward upper lip curvature (P<0.05). It is evident that differences in upper lip curvature and smile classification exist based on race, when comparing Chinese subjects with those of Caucasian descent, and gender.

Establishing identity using cheiloscopy and palatoscopy

Establishing a person's identity can be a very difficult process. Dental, fingerprint and DNA comparisons are probably the most common techniques used in this context, allowing fast and secure identification processes. However, since they cannot always be used, sometimes it is necessary to apply different and less known techniques. In this paper, the authors describe two unusual techniques: cheiloscopy and palatoscopy. It is known that due to their special features, both lip grooves and palatal rugae can be used successfully in human identification. This paper reviews the techniques of cheiloscopy and palatoscopy, and describes the different classifications and their advantages and limitations.

A simple and quantitative method for three-dimensional measurement of normal smiles

Smile reconstruction is one of the most challenging fields in plastic surgery. An understanding of the normal smile is essential in planning surgery for facial paralysis. The purpose of this study was to suggest a simple and quantitative method for the 3-dimensional analysis of smiles and to establish a basis for smile reconstruction in facial paralysis patients. The smiles of 50 volunteers (25 men and 25 women) were observed using a 6-mm digital video camera. Each subject had 10 points marked on the lips and nasolabial creases. Video editing programs were used to capture images of the resting and maximum smiles. The opacity of the image of maximum smile was adjusted and was merged with the resting image so that the migration of the points could be observed in 1 image. The migration distance (in millimeters) and the direction (in degrees) between each point were measured in frontal and both lateral views, and thus 3-dimensional vectors (x, y, z scalars) were obtained. The scalar values were converted to the values of a spherical coordinate system (distance, angle alpha and beta). Our work may offer a simple and quantitative method for measuring the smile and accurate guidance for reconstructive surgery.

Balanced Angular Profile Analysis

To evaluate current preferences and ethnic differences of female soft-tissue profiles, 71 profile photographs of famous female models were collected from Internet Web pages and divided into four groups (Korean, 22; Japanese, 15; Chinese, 16; and Western, 18). Eleven soft-tissue landmarks were recorded on each photograph and 16 angular measurements were made by using V-ceph (CyberMed, Inc., Seoul, Korea). Data from each group are presented to show the means, ranges, p and F values, standard deviations, and standard errors of each measurement. In addition, individual measurements for each group were compared with those of the other groups by one-way analysis of variance using a p value corrected for multivariable testing. Between-group mean value differences were calculated using a Tukey's studentized range test (HSD), at a significance level of p = 0.05. Most of the variables were similar in the groups. Significant between-group differences (p < 0.05) were found for angle of alar curvature point, profile convexity, interlabial contour, and nasolabial contour. In addition, we divided all data into two groups (Western and Asian). The t test (with significance level set to p = 0.05) was performed to compare the two. Significant between-group differences (p < 0.05) were found for angle of alar curvature, angle of labiale inferius, profile convexity, and lower lip projection angle, but no significant racial differences were found in terms of several profile angles. These findings suggest that point of ala curvature point, subnasale, and the labiale inferius of Asian models may differ from those of Western models. These peculiar angular patterns of Asian models led the authors to create a new characteristic angular concept, termed the "ethnic pyramid," which is composed of soft-tissue profile points of alar curvature point, subnasale, pronasale, and labiale inferius. This ethnic pyramid describes the characteristic patterns of the ethnic differences. The results of this study suggest that the soft-tissue profiles of famous female models have some common features but also show differences among ethnic groups and races. This simple method of profile analysis may provide aesthetic surgeons with a simple formula and reference data for creation and application of an attractive face. On the basis of their balanced angular profile analysis data, the authors suggest that appropriate and harmonious aesthetic operations reflecting these differences should be considered.