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 Table of Contents  
ORIGINAL ARTICLE
Year : 2017  |  Volume : 9  |  Issue : 1  |  Page : 1-7

Three-dimensional analysis of facial morphology in Brazilian population with Caucasian, Asian, and Black ethnicity


Department of Restorative Dentistry, School of Dentistry of Ribeirão Preto, São Paulo University, Ribeirão Preto, São Paulo, Brazil

Date of Web Publication2-Mar-2017

Correspondence Address:
Ana Maria Bettoni Rodrigues da Silva
Av. do Café s/n, Monte Alegre, Ribeirão Preto, São Paulo 14040-904
Brazil
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/2249-4987.201405

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  Abstract 

Aim: To compare facial features related to the nose, lips and face between the Caucasian, Asian, and Black ethnicity in the Brazilian population by means of linear measurements and proportion indices obtained from the analysis of three-dimensional (3D) images taken by 3D stereophotogrammetry.
Materials and Methods: Thirty healthy subjects, being 10 Caucasians, 10 Blacks and 10 Asians had reference points (landmarks) demarcated on their faces, 3D images were obtained (Vectra M3) and the following measurements were calculated: Facial proportion indices relative to the nose, lips and face. The statistical analysis was performed comparing the ethnic groups (one-way analysis of variance).
Results: The Blacks and Asians showed the greatest difference in the face analysis (width, height of the lower face, upper face index and lower face index – P < 0.05). In the comparisons between groups, differences were verified to the mouth width and lower lip vermilion height. In the nose analysis, the biggest differences were obtained for the proportion indices, being that Caucasians versus Asians and Caucasians versus Blacks have showed the largest differences.
Conclusion: This study found the presence of some similarities in the proportion indices of nose, lips and face between the ethnic groups of the Brazilian population, as well as some important differences that should be known to guide surgical and forensics procedures, among others.

Keywords: Computer-assisted, face, image processing, photogrammetry


How to cite this article:
da Silva AM, Magri LV, Andrade LM, da Silva MA. Three-dimensional analysis of facial morphology in Brazilian population with Caucasian, Asian, and Black ethnicity. J Oral Res Rev 2017;9:1-7

How to cite this URL:
da Silva AM, Magri LV, Andrade LM, da Silva MA. Three-dimensional analysis of facial morphology in Brazilian population with Caucasian, Asian, and Black ethnicity. J Oral Res Rev [serial online] 2017 [cited 2017 Mar 29];9:1-7. Available from: http://www.jorr.org/text.asp?2017/9/1/1/201405


  Introduction Top


With the emergence of numerous technological innovations, the dentistry has used an arsenal of equipment to facilitate the clinical practice and thus increases the possibilities of a more precise diagnosis. The three-dimensional (3D) digital photogrammetry, also known as digital stereophotogrammetry, uses fast acquisition systems and cameras that capture high-resolution images at different angles (principle of stereoscopy) and reconstruct a 3D image.[1] A software system is used to view and analyze the images, enabling the performance of linear morphological, angular, and volumetric measures. The coordinates x, y, z can be removed with the purpose of carrying out a wide range of statistical analyses. The indirect anthropometry, without physical contact with the individual, reduces the risk of injuries, prevents tissues deformation with measuring instruments, and offers a permanent file of assessments and data collection. As a result, it prevents an enormous amount of time involved in direct measurements.[1],[2]

When referring to the different facial patterns, the variation of the form of the craniofacial skeleton, in their normality, causes the several facial types: Long, medium, and short, which present peculiar characteristics. The morphometric differences of racial and ethnic minorities in the form and nasal angles in the populations of the world have been the focus of investigations.[3],[4] One of the most important aspects in the evaluation of facial esthetics is the nose shape of individuals. The nose shape is a signature that indicates the ethnic group, race, age, and gender.[5]

Sawyer et al.[6] reported the existence of the need for a 3D clinical record that allows precise measurement of the lips. The most important physical components on esthetic evaluation of the face would be the mouth, eyes, facial structure, hair, and nose, in that order.[7]

The necessity to establish normality values for innumerable linear measurements and angular and proportion indices of individual assessment for each kind of face, nose, and lips in the Brazilian population has led us to perform an anthropometric study with the objective of providing reliable reference data in accordance with the different ethnicities, and these measures were assessed by 3D stereophotogrammetry.

The aim of this study was to compare facial features related to the nose, lips, and face between the Caucasian, Asian, and Black ethnicity in the Brazilian population by means of linear measurements and proportion indices obtained from the analysis of 3D images taken by a 3D stereophotogrammetry.


  Materials and Methods Top


Study design

This was an observational, descriptive cross-sectional study.

Sample design

The sample was composed of thirty individuals: Ten individuals with Black ethnicity, ten with Asian ethnicity, and ten with Caucasian ethnicity (ntotal = 30), being that half of each group was composed of men (n = 15) and half by women (n = 15). The study included individuals between 18 and 40 years, who had not undergone any surgical process in the orofacial region that may have changed their facial anatomy. The study excluded individuals with a trauma history or tumors in the region of the head and/or neck, with orocraniofacial deformities, with neuromuscular diseases, and with cognitive impairment.

Ethical aspects

This study was performed after the submission and approval of the Research Ethics Committee of the School of Dentistry of Ribeirão Preto (FORP/USP), under protocol 08874612.3.0000.5419. All volunteers were informed about the research, its objectives, procedures, benefits, risks, and discomforts of the confidential nature of the data obtained and subsequently invited to participate in the study.

Procedures performed

A 3D stereophotogrammetry instrument was used (3D Vectra; Canfield Scientific, Fairfield, NJ, USA) to assess the morphology of the facial soft tissue. The Vectra 3D image system is a modular system for capturing of 3D images designed to capture and process images. This system is composed of 2 capsules, including 3 cameras (2 black-and-white and 1 color) and a projector in each capsule. Basically, the method of active stereophotogrammetry is used: A standard thin is designed in the facial surface, thus increasing the differences between different depth facial areas. They are subsequently captured synchronously, images in two dimensions of individuals in the period of 0.75 ms. With the use of software tools, the information is used to calculate the 3D reconstructions which can be further processed, analyzed, handled and measures. A calibration step is necessary daily before acquiring patient images or anytime the system is busy according to the manufacturer's instructions. The calibration allows the correct location of the x, y, and z coordinates and ensures the accuracy of the images.

Initially, the participant was seated in a comfortable chair, with indirect lighting, and a strip of elastic tissue on his/her head was then placed, in order to restrain hair and ensure the best face on display. The skin was cleaned with sterile gauze soaked in 70% alcohol, in order to remove any impurities, oiliness, and makeup residues. Anatomical landmarks were demarcated through the direct method of palpation and inspection on the facial surface of the participants with the help of a black eyeliner (Boticário ®), previously established by Ferrario et al.[8] and Sforza et al.[9] The landmarks were marked on the face by two operators, and the measurements obtained from 3D images were analyzed using the mean values of those two images. The inter-operator reproducibility was previously checked in the research laboratory where the study was conducted, with no statistically significant differences between the measurements obtained by the two operators. On the surface of all participants, facial 31 anthropometric reference points were identified and marked using black eyeliner pencil as follows.

  • Midline landmarks: Tr (trichion); G (glabella); N (nasion); Prn (pronasale); C (columella); Sn (subnasale); Ls (labiale superius); Sto (stomion); Li (labiale inferius); Sl (sublabiale); Pg (pogonion), and Me (menton)
  • Paired landmarks (right and left): Exr and Exl (exocanthion); Enr and Enl (endocanthion); Osr and Osl (orbitale superius); Orr and Orl (orbitale); Ftr and Ftl (frontotemporale); Chkr and Chkl (cheek); Zyr and Zyl (zygion); Tr and Tl (traguion); Alr and All (alare); Acr and Acl (nasal alar crest); Cphr and Cphl(crista philtri); Chr and Chl (cheilion); Gor and Gol (gonion) [Figure 1].
Figure 1: Landmark digitalization at the tri-dimensional image of the face (Vectra Face Sculptor)

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The landmarks in the soft tissue were marked with the black eyeliner, except for the points exocanthion (Ex), endocanthion (En), stomion (Sto), and cheilion (Ch) (hybrid landmarks) [Figure 1]. The facial analyzes were performed through the measures obtained from the 3D images, taken from the software Facial Sculptor (Vectra M3).

Landmark digitalization was performed on the 3D reconstructions using the marks made on the participants' skin before each acquisition: Indirect digital landmark identification was avoided as it has been reported to be less precise, especially in the perilabial region.[10],[11]

Measures and indices assessed

After obtaining the 3D images, linear distances were measured, which will be used in the calculation of the indices of facial proportions, adapted from Othman et al.[12] These distances, as well as how calculations of the indices were performed, are organized in [Table 1]. The nose was classified using the measure of nasal index: Extremely narrow nose (up to 39.99), very narrow nose (40–54.99), narrow nose (55–69.99), medium nose (70–84,99), wide nose (85–99.99), very wide nose (100–114,99), extremely wide nose (above 115).[13]
Table 1: Linear distances and indices of facial proportions for the face, nose, and lips

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Statistical analysis

Descriptive statistical analysis was performed and linear measures and indices of facial proportions were compared between ethnicity by analysis of variance (one-way), adopting 5% as significance level. The results are expressed in mean and standard deviation (parametric distribution).


  Results Top


Among the measures obtained for the face, those that present the largest differences were Asian compared to Black ethnicity (width, height lower face, upper face index, and lower face index, P < 0.05) [Table 2]. When were confronted the Caucasian versus Black, there were differences only in the height of the lower face (0.01) and on the lower face index (<0.001). In the comparison between Caucasian versus Asian, differences were found in the face width (0.002), facial morphological index (0.006), and upper face index (0.04).
Table 2: Mean values and standard deviation of linear measurements and proportion indices on the face, lip, and nose for Caucasian, Asian, and Black races and comparison between races of the evaluated parameters (analysis of variance, P>0.05)

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With relation to the lips, no statistical difference was obtained between the Caucasian and Asian ethnicity for any parameter evaluated (P > 0.05). In the other comparisons between races, differences were obtained in the width of the lips (0.002) and height of the lower lip vermilion (P = 0.004 between Caucasians and Blacks and 0.002 between Asians and Blacks). A big difference was also observed in the upper lip vermilion between Caucasians and Blacks (P < 0.001) [Table 2].

In the analysis of the measurements involving the nose, the largest differences were related with the proportion indices and not with the linear measurements. The comparisons between Caucasian versus Asian and Caucasian versus Blacks showed the greatest differences. For the linear measurements, only the width of the nose had a statistical difference among Caucasians and Blacks (<0.001). Large differences were not observed between the nose of Asians and Blacks, being that only the nasal index was different (0.006) [Table 2].

The Olivier classification was proposed to categorize the nose subtypes based on the Nasal Index, as previously described.[14] The [Figure 2] shows the Nasal Index and the number of individuals with each nose subtype according to the ethnicity which is based on the nasal index according to the ethnicity studied. In Caucasians, almost the entire sample had a narrow nose (90%), whereas in the Asians, the most frequently classification found was medium (60%) followed by narrow (30%) and in the Blacks the medium nose was also the most frequent (70%), followed by wide (30%).
Figure 2: Mean and standard deviations of the Nasal Index according to the ethnicity (Caucasian, Asian, and Black) and nose subtypes (Olivier classification), which is based on the Nasal Index. *Statistical significance (analysis of variance)

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  Discussion Top


The system of 3D Vectra stereophotogrammetry has proven to be reliable and accurate besides presenting an adequate repeatability.[14],[15] The reproducibility inter-operators have already been tested for other research group, without significant differences between operators.[14] This equipment can be used for various types of analysis, among these the analysis of facial soft tissues, which allows measurement of linear measurements and angular and areas that can be compared between different groups.[14] Facial characteristics specific to each race can be identified and measured with the use of stereophotogrammetry, in order to guide surgical procedures, esthetic, orthodontic, among others that seek to achieve or reestablish attractive facial features for that particular race and/or population.[16],[17]

Several morphological variables are important in determining the facial pattern of an individual, among which stands out the maxillomandibular relationship and gender. There appears to be an equal relationship between men and women with Class I Angle with respect to linear and facial area measurements.[18] The different ethnic backgrounds have their own characteristics that make them identifiable through proportion of relations between nose, face, eyes, and lips.[16]

With relation to face, we find the main differences between Black and Asian, being that in Blacks, the height of the lower face (Sn-Gn) was significantly higher when compared to the other groups. In analyzing the proportion indices, significant differences were also found between Asians and Blacks among all the evaluated parameters. The width of the face (Zy-Zy) was similar among Caucasians and Blacks (ns), but when those groups were compared to the Asians, significant differences were observed, being that the face of Asians subjects proved to be the widest. Similar results were obtained in other studies that showed marked differences in the face of Asian populations, in particular regarding the width and height of the lower face.[16],[19] Only two measurements were statistically different when comparing Caucasians and Blacks in this study, the height of the lower face (Sn-Gn) and the lower face index, which are related measurements, i.e., there seems to be a similarity between the facial proportions of Caucasians and Blacks, which differ from the Asian proportions. The facial similarity among Blacks and Caucasians not only happens in the evaluation of the height of the lower face but also substantially bigger in Blacks.

The lip measurements showed different relations of what was found in the face, because between the Asian and Caucasian groups, statistical significance was not found for any variable, unlike the Black group. The width of the mouth and the height of the upper and lower lip vermilion were the measures that showed differences, and in Blacks, they were significantly higher (P > 0.05). In a research developed with a Caucasian population, no differences were observed in the lip vermillion between men and women, and these results corroborate with our study, in which there was no distinction of gender in the sample.[17]

Wong et al.[16] studied the influence of labial in facial esthetic proportions and found large differences between Caucasians and Asians, mainly in the female group. They noted that the thickness of the lip in China is significantly higher than in Korean and Caucasian groups and that ethnic identification feature is of paramount importance in determining what is considered attractive and esthetic for this population. These results differ from our study and can be explained by the gender differentiation.

The identification of facial proportions that are considered attractive has always been a scientific pursuit, which must respect the cultural and ethnic differences. The anthropometric indices have permitted a greater knowledge about the facial proportions that could guide aesthetic procedures.[20],[21] The knowledge of the individual anatomical characteristics, ethical components, and personal perspectives should guide facial esthetic procedures.[16] Rossetti et al.[21] affirmed that the 3D facial distances are not related to the attractiveness and facial proportions in the population found are different from those considered ideal (golden ratio).

In the analysis of nose measurements, the differences were obtained for the proportion indices and not for the linear measurements. There was a greater similarity between Blacks and Asians, being that in this comparison, only the nasal index was different. The Caucasian group diverges from the others because it has lower width of the nose, nasal index, and greater protrusion of the nose tip. A study performed with a Chinese population showed that the nasal profile of these individuals tends to present reduced length and width increased, depending on the sexual dimorphism.[22] Troncoso Pazos et al.[23] also claim that the gender is an important influencing factor in nasal morphology, even comparing different ethnic groups.

One of the more variables structures of the face is the nose, and several studies have already been conducted showing the differences in this structure to depend on the ethnicity, age, and gender.[24],[25],[26] The nose of individuals has less projection on oriental faces and the intercanthal distance is greater, and the nose tip projection is significantly lower when compared to Caucasian individuals.[24] Leong and White [25] compared the proportions of nose in Caucasians individuals according with the ideal proportions and verified significant differences between them and suggested that there is a correct parameter in surgical procedures that follow these parameters ideals, often far from reality. Porter and Olson [26] found a great variability in the facial proportions of Black American women when compared to predetermined parameters.

Talbert et al.[27] developed a study that compared the facial morphology of Caucasian Americans and Blacks and found that men African-Americans present greater protrusion of the lip, greater prominence in the upper portion of the face and the periorbicular region. Caucasian men showed greater prominence of the tip of the nose and malar region. As for the African-American women, they had a greater facial width, wide alar base, and more protrusive lips. The Caucasian groups showed the point of the chin, malar region, and lower height of the most prominent analyzed faces. These differences are important in facial identification, especially for areas such as plastic surgery and forensics analysis.[12]

The Brazilian population is composed by a great diversity of ethnic groups and its derivations, so it is necessary a better understanding about the facial features that comprise those different groups. Through this study, it was possible to identify the presence of certain similarities of nose, lips, and face measurements between the ethnic groups studied, as well as some differences that should be known to guide surgical and forensics procedures, among others. Future studies should be conducted with the objective to verify the facial morphology of other ethnic groups of the Brazilian population, thereby providing new comparisons.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Acknowledgment

We would like to thank the São Paulo Research Foundation (FAPESP) that funded the purchase of the Vectra equipment fundamental for this research.

Financial support and sponsorship

São Paulo Research Foundation (FAPESP) supported the study.

Conflicts of interest

There are no conflicts of interest.

 
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Leong SC, White PS. A comparison of aesthetic proportions between the Oriental and Caucasian nose. Clin Otolaryngol Allied Sci 2004;29:672-6.  Back to cited text no. 24
    
25.
Leong SC, White PS. A comparison of aesthetic proportions between the healthy Caucasian nose and the aesthetic ideal. J Plast Reconstr Aesthet Surg 2006;59:248-52.  Back to cited text no. 25
    
26.
Porter JP, Olson KL. Analysis of the African American female nose. Plast Reconstr Surg 2003;111:620-6.  Back to cited text no. 26
    
27.
Talbert L, Kau CH, Christou T, Vlachos C, Souccar N. A 3D analysis of Caucasian and African American facial morphologies in a US population. J Orthod 2014;41:19-29.  Back to cited text no. 27
    


    Figures

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    Tables

  [Table 1], [Table 2]



 

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