Three-dimensional analysis of facial morphology

Functional and Cosmetic Considerations in Gender-Affirming Feminization Rhinoplasty

Gender-affirming facial surgery is increasing in prevalence, and rhinoplasty plays an integral role in its success. The nose displays considerable gender dimorphism, and maneuvers performed during gender-affirming rhinoplasty may differ considerably from those performed during cis-gender surgery. During feminization rhinoplasty in particular, cosmetic goals often rely on reductive techniques such as osteotomies, dorsal reduction, sidewall narrowing, tip narrowing, and alar base narrowing. These maneuvers collectively have important ramifications when considering the functional aspects of the nose. Herein, we outline the status of feminization rhinoplasty, and the interplay of cosmetic and functional considerations of the field.

Quantitative analysis of surgical landmarks of the face in fixed cadaveric heads: clinical and anatomical implications

PURPOSE

This study aimed to examine and analyze the presence of sexual dimorphism and symmetry/asymmetry in fixed cadaveric heads and their contributions to clinical practice.

METHODS

Measurements were conducted on 6 cadavers and 24 fixed cadaveric heads (n = 30) using a digital microcaliper to assess cranial dimensions, including surgical landmarks, facial index (FI), orbital index (OI), and the danger triangle of the face, offering crucial references for surgeons during surgical interventions.

RESULTS

Analyses were conducted on cadavers consisting of 10 females (33.3%) and 20 males (66.7%). Males demonstrated significantly higher values than females in terms of Zy-Zy (Zy = Zygion), nasal body, and width/length of the columella. Hyperleptoprosop types were the most frequently observed, followed by the leptoprosop type. Females exhibited megaseme characteristics according to OI on both sides. Additionally, the danger triangle of the face was greater in males compared than in females, suggesting a higher risk of infection in this region among males.

CONCLUSION

The observed sex differences in facial and nasal dimensions, along with facial indices, are crucial for customizing surgical procedures to individual patients. For example, the greater distance in the danger triangle among males highlights the importance of considering anatomical variations to avoid complications, such as septic cavernous sinus thrombosis. Integrating these measurements into preoperative planning can enhance the precision of facial reconstruction and aesthetic surgeries, thereby improving patient outcomes and safety.

Photographic Parameters in Three-Dimensional Facial Image Acquisition. A Scoping Review

OBJECTIVE

Orthognathic surgery is a viable and reproducible treatment for facial deformities. Despite the precision of the skeletal planning of surgical procedures, there is little information about the relations between hard and soft tissues in three-dimensional (3D) analysis, resulting in unpredictable soft tissue outcomes. Three-dimensional photography is a viable tool for soft tissue analysis because it is easy to use, has wide availability, low cost, and is harmless. This review aims to establish parameters for acquiring consistent and reproducible 3D facial images.

METHODS

A scoping review was conducted across PubMed, SCOPUS, Scientific Electronic Library Online (SciELO), and Web of Science databases, adhering to "Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews" guidelines. Articles presenting 3D facial photographs in the diagnostic phase were considered.

RESULTS

A total of 79 articles were identified, of which 29 were selected for analysis.

CONCLUSION

The predominant use of automated systems like 3dMD and VECTRA M3 was noted. User positioning has highest agreement among authors. Noteworthy aspects include the importance of proper lighting, facial expression, and dental positioning, with observed discrepancies and inconsistencies among authors. Finally, the authors proposed a 3D image acquisition protocol based on this research findings.

Ethnic variation in lower face anthropometry on facial computed tomography scans for patients seeking facial feminization surgery

BACKGROUND

Facial feminization surgery (FFS) is the most common form of facial gender-affirming surgery. One of the current knowledge gaps is the understanding of differences among racial groups in baseline craniofacial norms for transgender and nonbinary patients.

METHODS

All patients who sought consultation for FFS and underwent craniofacial computed tomography (CT) scans at a single institution between 2018 and 2023 were included. Patients who underwent previous facial surgeries were excluded. Chart reviews were conducted for patient characteristics, including race, age, hormone therapy duration, and prior gender-affirming surgeries. Racial categorizations included White, Latinx, African American, or Asian. Patients with other or multiracial identities were excluded. Lower face measurements were derived from preoperative facial CT scans. Comparative analyses were performed on all measurements among the racial groups.

RESULTS

In this study, 204 patients were included with an average age of 32.0 ± 10.2 years and a median hormone therapy duration of 2.0 years. The notable differences among the racial groups were: 1. Zygomatic width was the largest in Asian patients (13.5 ± 0.6 cm) compared to all other racial groups (p = 0.03), 2. Nasolabial angle was the smallest in African American patients (82.5 ± 13.1 degrees, p < 0.001), 3. Lower face height was the largest in African American patients (6.9 ± 0.7 cm, p < 0.001), and 4. Lateral mandibular flare was the largest in African American patients (0.4 ± 0.1 cm) and the smallest in Latinx patients (0.2 ± 0.1 cm, p < 0.001).

CONCLUSIONS

Specific target areas of FFS should be carefully considered to account for possible baseline ethnic differences. Relative facial proportions may also be a more salient surgical planning tool in transgender and gender nonbinary patients rather than absolute measurements alone.

Facial Analysis of Patients with Unilateral or Bilateral Cleft Lip and Palate Using 3D Stereophotogrammetry

OBJECTIVES

To evaluate the quantitative values of linear and angular facial anthropometrics in patients with unilateral cleft lip and palate (UCLP) and compare them with those of patients with bilateral cleft lip and palate (BCLP) using three-dimensional (3D) facial imaging.

DESIGN

Retrospective, observational, and cross-sectional study.

SETTING

Hospital for Rehabilitation of Craniofacial Anomalies/USP (HRAC/USP).

PATIENTS/ PARTICIPANTS

In total, 61 non-syndromic patients with CLP who underwent multidisciplinary treatment and rehabilitated with a prosthesis were enrolled and divided into those with UCLP (G1; n = 31) and those with BCLP (G2; n = 30).

INTERVENTION

Facial images were captured using a 3D camera after landmarks were marked on each patient's face. The software evaluated linear and angular parameters. Statistical tests were applied. Significance was determined as P < 0.05.

MAIN OUTCOME MEASUREMENTS

Overall, 22 linear and 13 angular measurements were evaluated.

RESULTS

The nasal length (P = 0.08), middle third of the face (P = 0.06), base nose width (P < 0.001), nasal root width (P < 0.001), nasal tip angle (P = 0.018), philtrum width (P < 0.001), lower face width (P = 0.039) and midfacial depth (P = 0.040) were significantly higher in G2; the upper cutaneous lip height was significantly higher in G1. Sexual dimorphism was observed except for linear measurements (linear distance between the labiale superius and labiale inferius landmarks, nasal root width, and upper cutaneous lip length) and angular measurements.

CONCLUSIONS

G2 had a greater length and width of nose and nasal root, nasal tip angle, philtrum width, and lower face width, midfacial depth, and midface third than G1. These findings also revealed the presence of sexual dimorphism.

Frontiers in Three-Dimensional Surface Imaging Systems for 3D Face Acquisition in Craniofacial Research and Practice: An Updated Literature Review

Digitalizing all aspects of dental care is a contemporary approach to ensuring the best possible clinical outcomes. Ongoing advancements in 3D face acquisition have been driven by continuous research on craniofacial structures and treatment effects. An array of 3D surface-imaging systems are currently available for generating photorealistic 3D facial images. However, choosing a purpose-specific system is challenging for clinicians due to variations in accuracy, reliability, resolution, and portability. Therefore, this review aims to provide clinicians and researchers with an overview of currently used or potential 3D surface imaging technologies and systems for 3D face acquisition in craniofacial research and daily practice. Through a comprehensive literature search, 71 articles meeting the inclusion criteria were included in the qualitative analysis, investigating the hardware, software, and operational aspects of these systems. The review offers updated information on 3D surface imaging technologies and systems to guide clinicians in selecting an optimal 3D face acquisition system. While some of these systems have already been implemented in clinical settings, others hold promise. Furthermore, driven by technological advances, novel devices will become cost-effective and portable, and will also enable accurate quantitative assessments, rapid treatment simulations, and improved outcomes.

Slim the face or not: 3D change of facial soft and hard tissues after third molars extraction: a pilot study

BACKGROUND

Whether slim the face or not after removed third molars is the concern of some orthodontic treatment candidates. The aim of this article is to explore the volume changes of facial soft and hard tissues after third molars extraction, as well as develop a reproducible clinical protocol to precisely assess facial soft tissue volume change.

METHODS

A non-randomized, non-blind, self-controlled pilot study was conducted. 24 adults aged 18-30 had ipsilateral third molars extracted. The body weight change was controlled within 2 kg. Structured light scans were taken under a standardized procedure pre-extraction (T0), three (T1), and six (T2) months post-extraction; CBCTs were taken at T0 and T2. The projection method was proposed to measure the soft tissue volume (STV) and the soft tissue volume change (STVC) by the Geomagic software. The hard tissue volume change (HTVC) was measured in the Dragonfly software.

RESULTS

The final sample size is 23, including 5 males (age 26.6 ± 2.5 years) and 18 females (age 27.3 ± 2.5 years). The HTVC was - 2.33 ± 0.46ml on the extraction side. On the extraction side, the STV decreased by 1.396 (95% CI: 0.323-2.470) ml (P < 0.05) at T1, and increased by 1.753 (95% CI: -0.01-3.507) ml (P = 0.05) at T2. T2 and T0 had no difference (P > 0.05). The inter and intra-raters ICC of the projection method was 0.959 and 0.974. There was no correlation between the STVC and HTVC (P > 0.05).

CONCLUSIONS

After ipsilateral wisdom teeth extraction, the volume of hard tissue on the extraction side reduces, and the volume of facial soft tissue does not change evidently. However, further research with large sample size is still needed. The STV measurement has excellent repeatability. It can be extended to other interested areas, including forehead, nose, paranasal, upper lip, lower lip and chin, which is meaningful in the field of orthodontics and orthopedics.

TRIAL REGISTRATION

ChiCTR, ChiCTR1800018305 (11/09/2018), http://www.chictr.org.cn/showproj.aspx?proj=28868 .

Using data-driven phenotyping to investigate the impact of sex on 3D human facial surface morphology

The effects of sex on human facial morphology have been widely documented. Because sexual dimorphism is relevant to a variety of scientific and applied disciplines, it is imperative to have a complete and accurate account of how and where male and female faces differ. We apply a comprehensive facial phenotyping strategy to a large set of existing 3D facial surface images. We investigate facial sexual dimorphism in terms of size, shape, and shape variance. We also assess the ability to correctly assign sex based on shape, both for the whole face and for subregions. We applied a predefined data-driven segmentation to partition the 3D facial surfaces of 2446 adults into 63 hierarchically linked regions, ranging from global (whole face) to highly localized subparts. Each facial region was then analyzed with spatially dense geometric morphometrics. To describe the major modes of shape variation, principal components analysis was applied to the Procrustes aligned 3D points comprising each of the 63 facial regions. Both nonparametric and permutation-based statistics were then used to quantify the facial size and shape differences and visualizations were generated. Males were significantly larger than females for all 63 facial regions. Statistically significant sex differences in shape were also seen in all regions and the effects tended to be more pronounced for the upper lip and forehead, with more subtle changes emerging as the facial regions became more granular. Males also showed greater levels of shape variance, with the largest effect observed for the central forehead. Classification accuracy was highest for the full face (97%), while most facial regions showed an accuracy of 75% or greater. In summary, sex differences in both size and shape were present across every part of the face. By breaking the face into subparts, some shape differences emerged that were not apparent when analyzing the face as a whole. The increase in facial shape variance suggests possible evolutionary origins and may offer insights for understanding congenital facial malformations. Our classification results indicate that a high degree of accuracy is possible with only parts of the face, which may have implications for biometrics applications.

A Cross-Sectional Study to Determine and Compare the Craniofacial Anthropometric Norms in a Selected Kenyan and Chinese Population

Background: Craniofacial anthropometry provides essential data for diagnosis and treatment planning, with the norms for many races having been investigated. The results reveal that facial morphometry varies greatly because of geographical, ethnic, and racial variations. This study aims to gather the normative anthropometric data and compare the differences in facial morphometry between the Kenyan population and that of the Chinese. Methods: Four vertical measurements (trichion-nasion, nasion-subnasale, subnasale-gnathion, and superaurale-subaurale) and 6 horizontal measurements (zygion-zygion, exocanthion-endocanthion, endocanthion-endocanthion, pupil-pupil, alare-alare, and chelion-chelion) were obtained manually from subjects with no craniofacial abnormality. Results: A total of 180 participants (90 Kenyans and 90 Chinese) were included. Among the Kenyans, males generally had greater dimensions in comparison to the Kenyan females with the exception of the upper third, lower third, and intercanthal, and interpupillary distances. Among the Chinese, there was a significant difference between the 2 genders with the exception of intercanthal distance. All measurements were greater in Chinese males in comparison to the females. Comparison between races shows that Kenyans had greater vertical measurements with exception of the ear length for both genders. The Chinese males had increased facial width and intercanthal distance, while the Chinese females showed increased intercanthal distance compared to Kenyans. Kenyans exhibited hyperleptoprosopic-type face, while Chinese exhibited mesoprosopic-type face, with none of the 2 groups conforming to the neoclassical canons. Conclusion: Kenyans generally have greater craniofacial measurements versus Chinese, except for the facial width and intercanthal distance for males and interorbital distance for females.

Three-dimensional analysis of modeled facial aging and sexual dimorphism from juvenile to elderly age

A detailed understanding of craniofacial ontogenetic development is important in a variety of scientific disciplines dealing with facial reconstruction, forensic identification, ageing prediction, and monitoring of pathological growth, including the effect of therapy. The main goals of this study were (1) the construction of the facial aging model using local polynomial regression fitting separately for both sexes, (2) evaluation of the aging effect not only on facial form as a whole but also on dimensions important for clinical practice, and (3) monitoring of the development of shape facial sexual dimorphism. Our study was based on the form and shape analysis of three-dimensional facial surface models of 456 individuals aged 14-83 years. The facial models were obtained using a structured light-based optical scanner and divided (for some analyses) into four age categories (juveniles, young adults, middle adults, and elderly adults). The methodology was based on geometric and classic morphometrics including multivariate statistics. Aging in both sexes shared common traits such as more pronounced facial roundness reducing facial convexity, sagging soft tissue, smaller visible areas of the eyes, greater nose, and thinner lips. In contrast to female faces, male faces increase in size until almost 30 years of age. After the age of 70, male facial size not only stagnates, like in females, but actually decreases slightly. Sexual dimorphic traits tended to diminish in the frontal and orbitonasal areas and increase in the gonial area.

Expanding the Classic Facial Canons: Quantifying Intercanthal Distance in a Diverse Patient Population

Background:

The intercanthal distance (ICD) is central to our perception of facial proportions, and it varies according to gender and ethnicity. Current standardized reference values do not reflect the diversity among patients. Therefore, the authors sought to provide an evidence-based and gender/ethnicity-specific reference when evaluating patients’ ICD.

Methods:

As per the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, a systematic search of PubMed, Medline, and Embase was carried out for studies reporting on the ICD. Demographics, study characteristics, and ICDs were extracted from included studies. ICD values were then pooled for each ethnicity and stratified by gender. The difference between men and women, and that across ethnicities and measurement types were compared by means of independent sample t-test and one-way ANOVA (SPSS v.24).

Results:

A total of 67 studies accounting for 22,638 patients and 118 ethnic cohorts were included in this pooled analysis. The most reported ethnicities were Middle Eastern (n = 6629) and Asian (n = 5473). ICD values (mm) in decreasing order were: African 38.5 ± 3.2, Asian 36.4 ± 1.6, Southeast Asian 32.8 ± 2.0, Hispanic 32.3 ± 2.0, White 31.4 ± 2.5, and Middle Eastern 31.2 ± 1.5. A statistically significant difference (P < 0.05) existed between all ethnic cohorts, between genders among most cohorts, and between most values stratified by measurement type.

Conclusions:

Our standards of craniofacial anthropometry must evolve from the neoclassical canons using White values as references. The values provided in this review can aid surgeons in appreciating the gender- and ethnic-specific differences in the ICD of their patients.

Facial and body sexual dimorphism are not interconnected in the Maasai

BACKGROUND

In this paper, we investigate facial sexual dimorphism and its' association with body dimorphism in Maasai, the traditional seminomadic population of Tanzania. We discuss findings on other human populations and possible factors affecting the developmental processes in Maasai.

METHODS

Full-face anthropological photographs were obtained from 305 Maasai (185 men, 120 women) aged 17-90 years. Facial shape was assessed combining geometric morphometrics and classical facial indices. Body parameters were measured directly using precise anthropological instruments.

RESULTS

Sexual dimorphism in Maasai faces was low, sex explained 1.8% of the total shape variance. However, male faces were relatively narrower and vertically prolonged, with slightly wider noses, narrower-set and lower eyebrows, wider mouths, and higher forehead hairline. The most sexually dimorphic regions of the face were the lower jaw and the nose. Facial width-to-height ratio (fWHR), measured in six known variants, revealed no significant sexual dimorphism. The allometric effects on facial traits were mostly related to the face growth, rather than the growth of the whole body (body height). Significant body dimorphism was demonstrated, men being significantly higher, with larger wrist diameter and hand grip strength, and women having higher BMI, hips circumferences, upper arm circumferences, triceps skinfolds. Facial and body sexual dimorphisms were not associated.

CONCLUSIONS

Facial sex differences in Maasai are very low, while on the contrary, the body sexual dimorphism is high. There were practically no associations between facial and body measures. These findings are interpreted in the light of trade-offs between environmental, cultural, and sexual selection pressures.

Morphologic reproducibility in 6 regions of the 3-dimensional facial models acquired by a standardized procedure: An in vivo study

INTRODUCTION

A standardized procedure was proposed to control involuntary motion and other factors during the capture of structural light scanning that could influence the morphology of 3-dimensional facial models; interoperator reproducibility was evaluated.

METHODS

Twenty subjects volunteered for facial scanning. Three researchers scanned each volunteer 3 times on the same day using the FaceScan structural light scanning system (Isravision, Darmstadt, Germany) and after the proposed procedure. Captures were done at 5-minute intervals. The 3 facial scans acquired by the same researcher were compared by reverse engineering software (Geomagic; 3D Systems, Rock Hill, SC). Six facial regions, including forehead, nose, paranasal, upper lip, lower lip and chin, and cheek, were divided. With the first scan as a reference, the other 2 scans were registered, and surface-to-surface distance maps were acquired to calculate the mean, standard deviation, and root mean squares (RMS) between 2 surfaces. The reproducibility between 3 researchers was then evaluated by a 1-way analysis of variance.

RESULTS

The mean of 6 facial regions was close to 0. The RMS of lip regions were largest (0.48-0.53 mm), the forehead was smallest (0.21 mm), and the others ranged 0.37 mm to 0.42 mm. The standard deviation was slightly smaller than RMS and had the same trend of change. There was no significant difference in RMS among the 3 researchers (P >0.05).

CONCLUSIONS

With the constraint of the standardized procedure, the morphologic reproducibility of facial models in 6 regions was satisfying.

Morphological Analysis of Nose in Patients of Tessier No. 0 Cleft With a Bifid Nose in China

Objective: Facial cleft involves complex malformations. No study assessed the facial deformity of Tessier No. 0 cleft with a bifid nose. Thus, we used anthropometric measurements to access the nose in patients. Methods: A total of 24 bifid nose deformities underwent surgery at our institution between 2010 and 2019. Standardized photographs were taken preoperatively and postoperatively. Landmarks were identified on these images; measurements for nasal analysis were performed and compared with the established Chinese norms. Surgical method differences were also analyzed. Results: The median follow-up time was 2.51 years. Postoperatively, there is a significant difference in comparison with preoperative in the nasal index, medial canthus and nose width index, nasolabial angle, nasofacial angle, ala length and nasal bridge length index, nasal tip protrusion and nasal width index, and nasal width and ala length index. Furthermore, the medial canthus and nose width index, and nasal width and ala length index were significantly larger in ordinary people, while ala length and nasal bridge length index and nasal tip protrusion and nasal width index were smaller. After surgery, most angles and index were standard except the nasolabial angle in the females, and ala length and nasal bridge length index in the males. Moreover, as for the group of costal cartilage transplantation, most index and angles have improved after surgery including nasolabial angle, nasofacial angle, ala length and nasal bridge length index, nasal tip protrusion and nasal width index, and nasal width and ala length index. However, only nasal tip protrusion and nasal width index, columella length and nasal tip protrusion index, and nasal width and ala length index in the silicone prosthesis group implantation has significance. Costal cartilage transplantation can also better improve ala length and nasal bridge length index than the silicone prosthesis implantation. Conclusion: Most defects can be repaired with surgery, but the outcome has a lack of evaluation. Thus, anthropometric assessment can serve as a material for nasal and reconstructive surgery.

Second-to-fourth digit ratio and facial shape in Buryats of Southern Siberia

BACKGROUND

The 2nd-to-4th digit ratio (2D:4D) is a putative predictor of a prenatal exposure to sex hormones. 2D:4D is sexually dimorphic (males < females). Studies, linking digit ratio and full facial shapes among Europeans, show that a low 2D:4D is associated with a set of male-specific facial features. Buryats - Mongolian people from Southern Siberia - demonstrate a different pattern of facial sexual dimorphism than Europeans (narrower and more vertically elongated faces in men as opposed to women).

AIM

The aim of the present study was to investigate the association between facial shape and the 2D:4D in comparison to the pattern of facial sexual dimorphism in Buryats.

SUBJECTS

Buryats: 88 men and 80 women aged 20 ± 2 years.

OUTCOME MEASURES

To assess relationship between facial shape and 2D:4D we used a geometric morphometric approach based on standardized full-face frontal photographs and direct measurements of the digit lengths among right-handed individuals.

RESULTS

The results revealed that 2D:4D was associated with facial morphology in Buryat men, and to a lesser extent in women. Narrower faces, elongated in the vertical direction, and a narrower lower facial outline, were characteristic of Buryat men with low 2D:4D ratios, which corresponded to the male-like facial shapes in Buryats.

CONCLUSIONS

In Europeans, such facial features were reported for men with a high 2D:4D, which corresponded more to female-like European facial shapes. Hence, our results show that sex-specific morphogenesis in humans is multidirectional, and that digit ratio is capable of predicting sex-specific facial traits even in populations with differing sexually-dimorphic morphology.

Craniofacial anthropometric investigation of relationships between the nose and nasal aperture using 3D computed tomography of Korean subjects

This study investigated the relationships of morphology and locations of the nose and nasal aperture by using major craniofacial landmarks on the human skull and face for craniofacial reconstruction/approximation of Koreans. In the frontal view, the positions of bony landmarks on the skull, including the nasal aperture, were correlated with the positions of nasal landmarks vertical to the transverse plane. In profile, the positions of bony landmarks on the skull were correlated with the positions of nasal landmarks horizontal to the coronal plane. Overall, 26 of the 76 measurements demonstrated significant correlations between the corresponding landmarks on the nose and nasal aperture. Simple regression equations were produced from the results. This study showed that the nose and nasal aperture are significantly related to each other in terms of their morphology and location in Koreans. The prediction guidelines, produced as regression formulas, can be applied to craniofacial reconstruction/approximation and bio-anthropological research of Korean skulls. The study results can also be used clinically in rhinoplasty and nasal reconstruction surgery.

Three-dimensional anthropometric analysis of eyelid aging among Chinese women

BACKGROUND

Eyelid morphology is highly susceptible to aging. Previous studies have described the process of eyelid aging in Caucasians; however, anthropometric data describing aging in Chinese eyelids are lacking. Therefore, this study aimed to quantitatively analyze the effect of aging on the eyelids of Chinese women through a three-dimensional (3D) anthropometry.

METHODS

In this prospective, cross-sectional study, 3D photos were captured from 188 healthy Chinese Han women, who were categorized into four age groups. Anthropometric landmarks were identified for the measurement of eyelid parameters, and a unified coordinate system was built into each subject. Linear and angular measurements were computed from the coordinates and were compared between the groups.

RESULTS

An age-related decrease was observed in the ocular width, outer canthal width, palpebral fissure height, and multiple angular measurements. This indicated upper eyelid ptosis, which reduced the lateral and superior visual field. Lateral shift of the upper eyelid arc was not observed. The lower eyelid underwent slight elevation with increasing age. Aging rendered the periorbital region esthetically less pleasing, as shown by changes in the multiple proportion indices computed. Furthermore, an intergroup comparison indicated that eyelid aging was accelerated after the age of 40 years among Chinese women.

CONCLUSION

This study used 3D photography to quantitatively analyze how eyelids in Chinese women changed with age. The anthropometric data collected could help with antiaging cosmetic surgery planning and postoperative assessment.

3D morphological classification of the nasolacrimal duct: Anatomical study for planning treatment of tear drainage obstruction

BACKGROUND

The purpose of this study is to analyze and classify morphological features of the nasolacrimal duct (NLD) through 3D reconstruction to help understand the causes and treatment of NLD obstruction.

METHODS

In this study, we included 63 males and 55 females who underwent autopsy without NLD obstruction with ages ranging from 20 to 78 years. The NLD was defined from the lacrimal fossa to the opening of the BNLD to the inferior meatus, and all continuous CT images showing the NLD were selected. Segmentation was performed semi-automatically, and the reconstruction and measurement of NLD was performed using the Mimics program.

RESULTS

Overall NLD length, bony nasolacrimal duct (BNLD) length, anteroposterior and transverse diameters at the entrance to the BNLD, anteroposterior and transverse smallest diameters of the BNLD, BNLD volume, and lacrimal sac BNLD angle were significantly higher in males than females (p < .05). BNLD direction in the coronal plane was slightly more likely to be inward. The most common type in both sexes was cylinder type (42.0%), males were more likely to have lower-thicker types (34.1%), and females more likely to have upper-thicker types (22.7%).

CONCLUSION

There were sex differences in NLD measurements, and females had significantly smaller NLDs. These results may partially explain the increased prevalence of primary acquired NLD obstruction in females. The BNLD tends toward the midline, and inclines posteriorly.

Sexual dimorphism in facial shape of modern Buryats of Southern Siberia

OBJECTIVES

The aim of the present study was to investigate sexual dimorphism in the full facial shape of modern Buryats-people of Southern Siberia of Mongolian origin.

METHODS

For this purpose, we have used geometric morphometrics based on standardized full-face frontal photographs. This allowed us to assess and visualize differences in facial shapes between Buryat men (n = 98) and women (n = 89). To specify the facial areas, where the differences occurred, we have complemented our analysis with standard anthropometric facial parameters based on approximations to the craniofacial and mandibular landmarks and soft-tissue morphology of specific facial areas.

RESULTS

Our results revealed that Buryat women have a set of sexually dimorphic features similar to those reported earlier for other Asian populations (a relatively wider and vertically shorter lower face, more round visible areas of the eyes, relatively narrower noses, smaller mouths, larger [in vertical dimension] foreheads, and relatively thinner upper lips, when compared to Buryat males). At the same time, Buryat women had a specific characteristic, distinguishing them from other world populations-a significantly higher upper face width-to-height ratio (fWHR) compared to males. This indicates that the high fWHR is not a universally male feature in humans, which raises a question of underlying developmental mechanisms.

CONCLUSIONS

Our results clearly demonstrate that some elements of sexually dimorphic facial shapes may differ across populations with different genetic and ecological backgrounds, and suggest that universal mechanisms of sex-specific facial morphogenesis still need to be clarified in the future.

3D Analysis of Facial Morphology of a Colombian Population Compared to Adult Caucasians

Objective:  The purpose of this study involves describing the facial morphology of a Colombian population with three-dimensional (3D) imaging, and comparing their facial morphology with the Caucasian to create a database for this ethnicity.

Materials and Methods:  The study, which included 135 subjects selected from the Valle University in Cali, Colombia, and 535 Caucasian subjects selected from the FaceBase–Data (1U01DE024449–01), was funded by the National Institute of Dental and Craniofacial Research. All images were taken in the natural head position (NHP) and captured using a stereo-photogrammetric camera system (3dMDface) to obtain a 3D image of each patient. The subjects were between 19 to 31 years of age, with a normal body mass index (BMI), and no craniofacial deformities. All images were plotted and analyzed using the 3dMDVultus software to calculate linear and angular measurements. Standard deviation (SD) and means were calculated for each measurement and analyzed using t -test for different samples.

Results:  The Hispanic population had wider eyes, more protruded upper and lower lips, wider face, and greater mandibular width. Caucasian females had a more acute full profile, larger middle third, and less protrusive lips. Understanding the facial morphology of different populations would help to establish a better diagnosis and treatment planning for each ethnicity.

Conclusions:  From this study, the following conclusions may be drawn:

1. The mean values of Colombian males showed greater measurements than females in the majority of measurements.

2. Caucasian females had a more acute full profile, larger middle and lower third, and less protrusive lips.

3. This study showed significant ethnic differences in the linear and angular measurements, showing us the importance of considering these findings in the diagnosis and treatment planning when a Hispanic population is involved. Soft tissue values should reflect the norms according to each ethnic population in order to achieve treatment goals.

A Comparison of 3D Facial Features in a Population from Zimbabwe and United States

OBJECTIVES

 The purpose of this study was to determine the differences in three-dimensional (3D) facial features in a population from Zimbabwe and the United States. In addition, this study seeks to establish an average facial template of each population allowing clinicians to treat patients according to their cultural esthetic perceptions.

MATERIALS AND METHODS

 Three hundred one subjects from Zimbabwe and the United States were carefully selected and recruited for the study. Each subject presented with a normal facial profile, no asymmetries, and normal body mass index. The 3D images were captured using the 3dMD cameras. All images were further separated into male and female groups of the respective populations and imported to a dedicated software for analysis.

STATISTICAL ANALYSIS

 The 3D facial images were constructed using Rapidform 6 software to recreate a composite facial average for each group representing a male and female average 3D face of Zimbabwean (Zim) and United States origin.

RESULTS

 The linear measurements showed that the maximum average distance between the Zim-M and Zim-F was 1.24 mm and the minimum distance between the African American (AA)-M and AA-F was 0.24 mm. This was the absolute distance. When the signed linear measurements were taken into consideration, the maximum average distance between Zim-F and AA-M was 1.22 mm and the least average distance between the Zim-M and AA-M was 0.22 mm. The absolute color histograms showed greatest similarity between the Zim-M and AA-M at 58% and the Zim-F had a 25 and 27% similarity with the AA-F and Zim-M, respectively.

CONCLUSION

 The Zim-F showed the most variable features with a broader face, prominent forehead, and retruded alar base compared with their male counterparts and the Zim-M showed a wider prominent malar/zygomatic region, and prominent lateral supraorbital regions. There was a high similarity of 58% between the Zim-M and the AA-M, with the Zim-M showing a more protrusive superciliary arches, and a lateral zygomatic region tapering to the root of the nose.

Craniofacial Anthropometric Profile of East Asians

Facial anthropometric data has significant ethnic variation. East Asia, comprised of fourteen countries, represents a significant proportion of the global population. This systematic review presents the facial anthropometric data collected from these countries. The systematic review was conducted in accordance with PRISMA guidelines. An electronic search of the MEDLINE database returned 3054 articles. Twenty articles were considered eligible for inclusion. Nine studies were conducted in China, 1 in Indonesia, 2 in Japan,3 in Korea, 4 in Malaysia, and 1 was a multicentre study conducted in China, Japan, Thailand, and Vietnam. Qualitative and quantitative parameters were extracted from the20 studies. No data was found for the other East Asian countries. There is a paucity of facial anthropometric data for East Asian countries despite their high burden of craniofacial anomalies and a strong demand for cosmetic facial surgery, both of which would benefit from the collection of robust craniofacial norms. It is in the interest of both the craniofacial surgeon and the East Asian patient to collect baseline facial anthropometric data for this population.

Accuracy evaluation of tridimensional images performed by portable stereophotogrammetric system

Abstract Introduction Human facial characteristics vary according to individual dental occlusion, facial harmony, orofacial musculature and the format and configuration of craniofacial structures. Traditionally, anthropometric measurements have been acquired through direct evaluation of subjects in a clinical environment using calipers and metric tapes to measure distances between arches and landmarks. Scientific breakthroughs have enabled the digitization of data and introduced the possibility of quick, precise, radiation-free acquisitions; details can be archived for future analysis and easily shared with patients and colleagues. Among new facial analysis methods, the stereophotogrammetry technique has emerged, which uses a group of cameras to take many photographs of a subject in rapid succession from multiple angles. Nowadays, portable stereophotogrammetric systems are being proposed, as they are more practical and easier to use. Objective The aim of this work was to analyze the accuracy and reproducibility of a portable 3D stereophotogrammetric system (Vectra H1, Canfield, Fairfield, NJ, USA) in measuring soft facial tissues of 30 participants, defining measures of a cube and comparing these measurements with those obtained by a set 3D stereophotogrammetric system (Vectra M3, Canfield, Fairfield, NJ, USA) with previously validated accuracy and reproducibility through quantitative analysis of possible errors. Material and method Thirty temporary landmarks were used to measure (in mm) 34 distances in 30 participants (n = 30). Regarding the cube, 12 angles and 9 linear distances were evaluated. Result The results obtained by the established methodology indicated that the Vectra H1 portable system has shown accuracy and reproducibility equal to that of the Vectra M3 set system. Conclusion Data analysis and correlation to literature findings show Vectra H1's capability to reliably capture tridimensional images, which makes it practical for use in diverse clinical applications.

The South Asian facial anthropometric profile: A systematic review

PURPOSE

Craniofacial anatomy, as measured by facial anthropometric data, varies significantly between races. South Asia, comprised of eight countries, represents a large proportion of the global population and is the fastest-growing region of the world. This systematic review presents the facial anthropometric data collected for populations from this region.

MATERIALS AND METHODS

This systematic review was conducted in accordance with PRISMA guidelines. A systematic review of the literature was conducted by an electronic search of the MEDLINE and Cochran databases, returning 1675 articles. Bibliographies of accepted articles were screened to identify further eligible studies.

RESULTS

A total of 12 articles were considered eligible for the systematic review. Two studies were conducted in Bangladesh, 7 in India, and 3 in Nepal. No facial anthropometric data were found for populations from Afghanistan, Bhutan, Maldives, Pakistan, or Sri Lanka. Qualitative and quantitative parameters from the 12 studies were extracted.

CONCLUSION

There is a paucity of facial anthropometric data for South Asian populations. As South Asia has a significant prevalence of craniofacial anomalies and a burgeoning cosmetic facial surgery market, it is in the interest of both the craniofacial surgeon and the South Asian patient to collect baseline facial anthropometric data for this population.

Anthropometric Analysis of the Nigerian Face: Any Conformity to the Neoclassical Canons?

This study defines the facial anthropometric and aesthetic measurements in young Nigerians. This is a prospective cohort study involving facial anthropometric measurement in young adults without craniofacial abnormalities. Ten anthropometric measurements (upper facial height (tr-n), mid-facial height (n-sn), lower facial height (sn-gn), height of auricle (sa-sba) bilaterally, intercanthal width (en-en), palpebral fissure width (en-ex) bilaterally, face width (zy-zy), nose width (al-al), mouth width (ch-ch) and the interincisal distance) were determined. Proportions were compared with neoclassic cannons, published North American and Asian norms 151 individuals consisting of 50 males and 51 females with age range from 16 to 31 (23.9 + 2.49) were enrolled. Only 1% of the study population had equal facial thirds, the midface was the shortest of the facial thirds and the male gender generally had larger mean values of the facial dimensions than the female gender. About half of the participants had the lower third > upper third > middle third, the intercanthal width was equal to the nasal width in only about a tenth of the participants and less than the nasal width in majority (88.1%) of the participants and the mean interincisal distance was 51.1 (SD ± 6.997). The anthropometric measurements from this Nigerian study do not conform to the neoclassical cannons. Racially sensitive facial canons and measurements are advocated during reconstructive and aesthetic interventions in the craniofacial region.

Three-Dimensional Anthropometric Evaluation of Facial Morphology

OBJECTIVES

The objectives of this study were to evaluate sexual dimorphism for facial features within Colombian and Mexican-American populations and to compare the facial morphology by sex between these 2 populations.

MATERIALS AND METHODS

Three-dimensional facial images were acquired by using the portable 3dMDface system, which captured 223 subjects from 2 population groups of Colombians (n = 131) and Mexican-Americans (n = 92). Each population was categorized into male and female groups for evaluation. All subjects in the groups were aged between 18 and 30 years and had no apparent facial anomalies. A total of 21 anthropometric landmarks were identified on the 3-dimensional faces of each subject. The independent t test was used to analyze each data set obtained within each subgroup.

RESULTS

The Colombian males showed significantly greater width of the outercanthal width, eye fissure length, and orbitale than the Colombian females. The Colombian females had significantly smaller lip and mouth measurements for all distances except upper vermillion height than Colombian males. The Mexican-American females had significantly smaller measurements with regard to the nose than Mexican-American males. Meanwhile, the heights of the face, the upper face, the lower face, and the mandible were all significantly less in the Mexican-American females. The intercanthal and outercanthal widths were significantly greater in the Mexican-American males and females. Meanwhile, the orbitale distance of Mexican-American sexes was significantly smaller than those of the Colombian males and females. The Mexican-American group had significantly larger nose width and length of alare than the Colombian group regarding both sexes. With respect to the nasal tip protrusion and nose height, they were significantly smaller in the Colombian females than in the Mexican-American females. The face width was significantly greater in the Colombian males and females.

CONCLUSIONS

Sexual dimorphism for facial features was presented in both the Colombian and Mexican-American populations. In addition, there were significant differences in facial morphology between these 2 populations.