Systematic review on forensic craniofacial reconstruction. I. facial soft-tissue thickness.

Forensic anthropologists are traditionally interested in facial approximations and reconstruction of physiognomies of individuals from past populations and creation of lifelike features onto unknown skulls retrieved from forensic or bioarchaeological contexts. Present review article examines the significance of facial soft-tissue thickness (FSTT) in craniofacial reconstruction by revisiting the studies published in the recent past decade (2010-21). The searches for published articles mentioning the FSTT and related topics over these years were performed using the following search engines: PubMed, ScienceDirect, Web of Science, and Scopus. A total of 325 research articles were identified using different keywords, out of which 84 studies were found relevant for systematic review presented in this article. The selected studies were further analyzed based on the adopted study design, radiographic modality used for estimating FSTT, and generated databases and their advantages and limitations. Out of 84 relevant articles, 30 articles presented databases for sex, age, and ethnicity-dependent variations in soft tissue thickness measurements. Finally, 17 studies reporting sexual dimorphic variations in FSTT values estimated in supine or upright postured individuals (aged 18-90 years and above) were considered for meta-analysis. This article gives a decisive outlook on research trends in FSTT estimations, its contributions in refining craniofacial reconstruction technology, and identifying where we lack and where we can improve.

Comparison Of Soft Tissue Chin And Lower Lip Thickness In Adult Patients With Various Mandibular Divergence Patterns.

BACKGROUND: The influence of hard tissue discrepancies on soft tissue cannot be ignored. The divergence or angle of the mandible can influence the lower lip and chin (soft tissue), similar to the influence of incisors inclinations on the pro/ retrusion of the lips. Hence this study was carried out to find out the impact of mandibular divergence patterns on the contour and thickness of lower facial soft tissues. METHODS: Using the Lateral cephalograms of 105 subjects, Lip thickness was measured between the protruding endpoint of the maxillary incisors (U1) to the stomion point (St) and between the infra dentale (Id) and labrale inferius (Li). Soft tissue chin thickness was measured between the landmarks at hard tissue bony pogonion (Pog) to its opposite point on soft tissue (Pog'), hard tissue gnathion (Gn) to soft tissue gnathion (Gn') and hard tissue menton (Me) to its opposite point on ST menton (Me'). RESULTS: Lower lip thickness from Id-Li (infradentale labrale inferius) was greater in subjects with mandibular hyperdivergent pattern (p-value 0.097) while soft tissue chin thickness was decreased in hyperdivergent and increased in individuals with mandibular hypodivergence in both genders (p-value at gnathion was 0.596, menton was 0.023, and pogonion was 0.004, respectively). CONCLUSIONS: Lower lip thickness was increased in the individuals with mandibular hyperdivergence measured from infradentale to labrale inferius. While increased soft tissue thickness was observed at points gnathion and menton in patients with mandibular hypodivergence with no obvious difference at pogonion point.

Lip and facial training improves lip-closing strength and facial morphology.

OBJECTIVE: Childhood is an important period for lip-closing strength (LCS) development, and failure to acquire LCS during childhood leads to various adverse health effects, such as mouth breathing. The purpose of this study was to examine the effectiveness of device-free lip and facial training in preschool children. DESIGN: The participants were divided into training and control groups. Both groups comprised 123 children aged 3-4 years, and only the training group received lip and facial training (i.e., opening and closing the lips and protruding the tongue) for 1 year. A two-way repeated measures analysis of variance was applied to compare the interaction effects of LCS and facial linear distance and angle by year (initial year vs. 1 year later) and group (training vs. control group). In addition, paired t-tests were used to test the changes in LCS and facial linear distance and angle after 1 year in both groups. Furthermore, the same analysis was performed in children with weak LCS in both groups (incompetent lip seal [ILS]). RESULTS: The LCS of children in the training group significantly increased after training compared with that in the control group, whether the analysis included all children or children with ILS alone. Lip and facial training for children with ILS reduced both the upper and lower lip protrusion; children with ILS without training had increased lip protrusion after 1 year. CONCLUSIONS: Lip and facial training for children with ILS effectively improved LCS and lip morphology, thereby preventing increased lip protrusion.

Comparative Evaluation of Cranial Base Length and Flexure on Facial Parameters in Hypodivergent, Normodivergent and Hyperdivergent Patients: A Retrospective Cephalometric Study.

AIM: The aim of the study was to assess the influence of cranial base length (CBL) and Flexure on facial parameters in Hypodivergent, Normodivergent, and Hyperdivergent patients. MATERIALS AND METHODS: Around 60 standardized cephalograms were divided into Hypodivergent, Normodivergent, and Hyperdivergent groups (20 each) based on the FMA angle. The CBL, cranial flexure (CF), and various facial parameters were measured for each case. The results were analyzed for the correlation between Cranial and facial parameters in each of the three study groups. RESULTS: Comparison and Pairwise Comparison of variables between study groups were done using ANOVA and Tukey's post hoc Test. Cranial base length, mandibular body length, LAFH, N-Me-Go angle (p-value <0.001), and Jarabak's ratio were found to be significantly different between the groups. Pearson's Correlation showed that most of the facial parameters had a significant correlation with CBL in Hypodivergent groups. CONCLUSION: The CBL is more closely related to facial parameters in vertical dysplasia individuals than CF. The CBL is positively correlated to facial variables, especially in Hypodivergent individuals. The N-Me-Go Angle introduced in the study was significantly different in all three vertical facial types studied; hence, it cannot be used as a valuable diagnostic tool. CLINICAL SIGNIFICANCE: Changes in the length and flexure of the cranial base influence the anteroposterior position of jaw bases. The influence of the cranial base on the development of vertical dysplasias is not studied much, hence the present study aims at resolving this lacuna in literature.

[Injection anatomy-a new discipline in aesthetic medicine]. / Injektionsanatomie ­ eine neue Disziplin der ästhetischen Medizin.

The basic anatomical understanding of aesthetic medicine has changed fundamentally since the turn of the millennium. With the advent of modern minimally invasive injection procedures using botulinum toxin and hyaluronic acid fillers, anatomical structures that had previously received little attention and were not considered relevant have steadily gained in importance and moved into the scientific focus. Understanding the three-dimensional arrangement of the face with its defined anatomical layers and compartments serves the procedural dermatologist in the sense of a navigation system to optimize treatment success and patient safety when performing aesthetic injections in the facial region. The principles of the biomechanical interaction of the structures are of elementary importance in the creation of individual treatment plans for the implementation of natural and balanced therapeutic results. Modern injection anatomy as an interdisciplinary subject of the three fields of anatomy, dermatology and plastic surgery makes a decisive contribution here.

Do facial soft tissue thicknesses change after surgeries correcting dental malocclusions? An intra- and inter-patient statistical analysis on soft-tissue thicknesses in BSSO + LFI surgeries.

OBJECTIVES: The aim of this study was to analyse changes in facial soft tissue thickness (FSTT) after corrective surgeries for dental malocclusion. The correlation between body mass index (BMI) and sex of patients and their FSTT before undergoing surgery was analysed. MATERIALS AND METHODS: Cone beam computed tomography of seventeen patients that underwent Le Fort I osteotomy in combination with bilateral sagittal split osteotomy were collected. Hard and soft tissue landmarks were selected basing on the interventions. FSTT were computed, and measurements from pre- to post-operative were compared. The relationship between FSTT, sex, and BMI was investigated. RESULTS: Considering the comparison between pre- and post-operative measurements, any significant difference emerged (p > .05). The Pearson's correlation coefficient computed between BMI and the FSTT (pre-operative) showed a correlation in normal-weight patients; the region-specific analysis highlighted a stronger correlation for specific landmarks. Higher median values emerged for women than for men; the subset-based analysis showed that women presented higher values in the malar region, while men presented higher values in the nasal region. CONCLUSIONS: The considered surgeries did not affect the FSTT of the patients; differences related to BMI and sex were found. A collection of FSTT mean values was provided for twenty landmarks of pre- and post-operative of female and male subjects. CLINICAL RELEVANCE: This exploratory analysis gave insights on the behaviour of STT after maxillofacial surgeries that can be applied in the development of predictive methodologies for soft tissue displacements and to study modifications in the facial aspect of the patients.

Tridimensional assessment of the mandibular angle in patients with different skeletal patterns by cone-beam computed tomography scans: a retrospective study.

BACKGROUND: Since the muscles of chewing are involved in the region of the mandibular angle, important structures in surgical and orthodontic procedures, to study its morphological aspects and the possible influence of different patterns of skeletal development would be of interest. Thus, this study aimed to assess the influence of patient characteristics - such as sex, skeletal malocclusion (Class I, Class II, and Class III) and facial type (brachycephalic, mesocephalic, and dolichocephalic) - on the width, height, thickness, and volume of the mandibular angle, using cone-beam computed tomography (CBCT) scans. METHODS: CBCT scans were assessed - 144 men and 154 women, total of 298 - and classified according to skeletal patterns (skeletal malocclusions and facial types). Width, height, and thickness of the mandibular angle were measured using OnDemand 3D software. The volumetric measures of the mandibular angle were obtained using the ITK-SNAP software. Analysis of Variance (multiway ANOVA) with Tukey's post-hoc test compared the data, with a 5% significance level. RESULTS: Among the factors studied, sex significantly influenced all the analyzed variables (height, width, thickness, and volume of the mandibular angle) (p < 0.05); in general, male individuals presented higher values than females. In some cases, the skeletal malocclusion and facial type factors influenced only the width and height variables (p < 0.05); in general, the Class III and dolichocephalic individuals presented higher values in relation to the other types of skeletal malocclusions and facial types. CONCLUSIONS: Variations in the craniofacial growth pattern, considering the different skeletal malocclusions and facial types, had some influence in the width and height dimensions of the mandibular angle. Furthermore, sex influenced all the studied variables.

Accuracy in predicting soft tissue changes of orthodontic class III cases using Dolphin® software.

OBJECTIVES: The prediction of posttreatment outcomes is conducive to the final determination of ideal therapeutic options. However, the prediction accuracy in orthodontic class III cases is unclear. Therefore, this study conducted exploration on prediction accuracy in orthodontic class III patients using the Dolphin® software. MATERIALS AND METHODS: In this retrospective study, lateral cephalometric radiographs of pre- and posttreatment were collected from 28 angle class III adults who received completed non-orthognathic orthodontic therapy (8 males, 20 females; mean age = 20.89 ± 4.26 years). The values of 7 posttreatment parameters were recorded and inserted into the Dolphin® Imaging software to generate a predicted outcome, and then the prediction radiograph and actual posttreatment radiograph were superimposed and compared in terms of soft tissue parameters and landmarks. RESULTS: The prediction showed significant differences with the actual outcomes in nasal prominence (the difference between the prediction and the actual value was - 0.78 ± 1.82 mm), the distance from the lower lip to the H line (0.55 ± 1.11 mm), and the distance from the lower lip to the E line (0.77 ± 1.62 mm) (p < 0.05). Point subnasale (Sn) (an accuracy of 92.86% in the horizontal direction and 100% in the vertical direction in 2 mm) and point soft tissue A (ST A) (an accuracy of 92.86% in the horizontal direction and 85.71% in the vertical direction in 2 mm) were proven to be the most accurate landmarks, while the predictions in the chin region were relatively inaccurate. Furthermore, the predictions in the vertical direction were of higher accuracy compared to the horizontal direction except for the points around the chin. CONCLUSIONS: The Dolphin® software demonstrated acceptable prediction accuracy in midfacial changes in class III patients. However, there were still limitations for changes in the chin and lower lip prominence. CLINICAL RELEVANCE: Clarifying the accuracy of Dolphin® software in predicting soft tissue changes of orthodontic class III cases will facilitate physician-patient communication and clinical treatment.

Mastering Midface Injections.

Injectable filler is one of the most common cosmetic procedures performed annually. An aging face shows a characteristic loss of volume in the deep fat pads of the midface. The goal of midfacial rejuvenation with injectable filler is to restore lost volume, with the suborbicularis fat pad and deep medial cheek fat being the most critical areas. Filler can be instilled here with a cannula or needle with successful outcomes. However, this procedure is not without complications if proper technique and underlying anatomy are not respected.

Anthropometric analysis of orbital and nasal parameters for sexual dimorphism: New anatomical evidences in the field of personal identification through a retrospective observational study.

Orbital and nasal parameters among modern humans show considerable variation, which affects facial shape, and these characteristics vary according to race, region, and period in evolution. The aim of the study was to ascertain whether there are sex differences in the orbital and/or nasal indexes and/or the single measurements used to calculate these in a Kosovar population. The following parameters were taken into consideration: orbital height (OH), orbital width (OW), nasal height (NH), and nasal width (NW). The ratios between orbital index/nasal index (RONI) were calculated. All measurements were obtained from a population sample comprising 408 individuals. The accuracy in sex prediction was 52.86% (CI95% = 45.05%-60.67%) for NW and 64.96% for NH (CI95% = 57.50%- 72.42%). The difference between male and female indexes was statistically significant (P < 0.05). The anthropometric study revealed that only NW and NH are configured as predictors of sexual dimorphism. It could be useful to increase the number of samples to test the discriminant function in other population groups.

Visual Attention, Bias, and Social Dispositions Toward People With Facial Anomalies: A Prospective Study With Eye-Tracking Technology.

BACKGROUND: Facial attractiveness influences our perceptions of others, with beautiful faces reaping societal rewards and anomalous faces encountering penalties. The purpose of this study was to determine associations of visual attention with bias and social dispositions toward people with facial anomalies. METHODS: Sixty subjects completed tests evaluating implicit bias, explicit bias, and social dispositions before viewing publicly available images of preoperative and postoperative patients with hemifacial microsomia. Eye-tracking was used to register visual fixations. RESULTS: Participants with higher implicit bias scores fixated significantly less on the cheek and ear region preoperatively (P = 0.004). Participants with higher scores in empathic concern and perspective taking fixated more on the forehead and orbit preoperatively (P = 0.045) and nose and lips (P = 0.027) preoperativel. CONCLUSIONS: Participants with higher levels of implicit bias spent less visual attention on anomalous facial anatomy, whereas participants with higher levels of empathic concern and perspective taking spent more visual attention on normal facial anatomy. Levels of bias and social dispositions such as empathy may predict layperson gaze patterns toward those with facial anomalies and provide insights to neural mechanisms underlying the "anomalous is bad" paradigm.

Is the distribution of cortical bone in the mandibular corpus and symphysis linked to loading environment in modern humans? A systematic review.

OBJECTIVE: The human mandible is a unique bone with specific external and internal morphological characteristics, influenced by a complex and challenging loading environment. Mandibular cortical thickness distribution in cross-sections is reported to be related to facial divergence patterns, cultural and dietary habits and more generally, specific loading environment. This review hypothesises that a process of environmental mechanical sensitivity is involved in the distribution of cortical bone in the mandibular corpus and symphysis in modern humans, and that loading regimes can influence this distribution pattern. Based on a review of the recent literature, this study aims to answer the following question: "Is the distribution of cortical bone in the mandibular corpus and symphysis linked to the loading environment in modern humans?" DESIGN: A systematic review was undertaken using the PubMed/Medline, Scopus and Cochrane Library databases for publications from 1984 to 2022 investigating the relationship between cortical bone distribution in the mandibular corpus and the loading environment. A subgroup meta-analysis was performed to determine the overall effect of facial divergence on cortical thickness. RESULTS: From a total of 2791 studies, 20 fulfilled the inclusion criteria. The meta-analyses were performed in eight studies using a randomised model, finding a significant overall effect of facial divergence on cortical thickness in posterior areas of the mandible (p < 0.01). CONCLUSIONS: Within the limitations of this review, specific loading regimes and their consequent variables (diet, culture, facial divergence) were linked to cortical thickness distribution. Sex was found to be unrelated to cortical thickness pattern.

3D Computed Tomography vs. 2D radiography: comparison of 3D direct anthropometry with 2D norm calculations and analysis of differences in soft tissue measurements.

OBJECTIVE: The aim of this study was twofold: (1) to compare soft tissue measurements of the same distances obtained from 3D computed tomography reconstructions with 2D cephalometric radiograms, (2) to compare data from 3D measurements from direct anthropometry and 2D "norms" for the facial measurements. PATIENTS AND METHODS: A total of 40 Caucasian patients that had their CBCT scans for various dental and dentoskeletal reasons were enrolled in this study. All the patients had large field of view (from the forehead to the chin). The data were stored in DICOM format and imported into a software for 3D reconstructions. After 3D facial soft tissue model generation, the distances between 18 soft tissue points were measured. The 3D soft tissue analysis was performed, and the facial indices were calculated. The mean 3D values were compared with 2D measurements performed on lateral cephalograms and Arnett's and Farkas' norms. The measurements were statistically compared using Student's t-test. RESULTS: Assessments from 2D and 3D measurements showed no statistical difference except for the distance Pogonion (for both male and female) and Labial superius prominence (females) to the True Vertical Line in 2D /Plane in case of 3D measurements. There was a significant difference between all 3D measurements and Arnett's and anthropometric Farkas' "norms". The mean difference between Farkas' "norms" and 3D measurements was within 3 mm for 70% of measurements. CONCLUSIONS: According to the results, 3D soft tissue analysis allows for complete diagnostic determination. The 3D "norms" are to be verified on a greater sample.

Heritability of cephalometric variables of airway morphology in twins with completed active growth.

BACKGROUND: The interplay between genetic and environmental impacts on dental and facial morphology has been widely analyzed, but little is known about their relative contributions to airway morphology. The aim of this study was to evaluate the genetic and environmental influences on the cephalometric variables of airway morphology in a group of postpubertal twins with completed craniofacial growth. MATERIALS AND METHODS: The materials comprised lateral head cephalograms of 94 pairs of twins (50 monozygotic, 44 dizygotic) with completed craniofacial growth. Zygosity was determined using 15 specific DNA markers. The computerized cephalometric analysis included 22 craniofacial, hyoideal, pharyngeal structural linear and angular variables. Genetic analysis and heritability estimation were performed using maximum likelihood genetic structural equation modeling (GSEM). Principal component analysis (PCA) was used to assess the correlations between cephalometric measurement variables. RESULTS: Upper airway dimensions showed moderate to high genetic determination (SPPW-SPP and U-MPW: a2 = 0.64 and 0.5, respectively). Lower airway parameters showed only common and specific environmental determination (PPW-TPP a2 = 0.24, e2 = 0.38; LPW-V c2 = 0.2, e2 = 0.63; PCV-AH c2 = 0.47, e2 = 0.28). The relationship between the maxilla and the hyoid bone (for variables PNS-AH, ANS-AH d2 = 0.9, 0.92, respectively) showed very strong additive genetic determination. The size of the soft palate was affected by additive and dominant genes. Its length (SPL) was strongly influenced by dominant genes, while its width (SPW) showed a moderate additive genetic influence. Owing to correlations in the behavior of variables, the data could be expressed in 5 principal components that jointly explained 36.8% of the total variance. CONCLUSIONS: The dimensions of the upper airway are strongly determined by genes, while the parameters of the lower airway depend mainly on environmental factors. TRIAL REGISTRATION: The protocol has been approved by the Kaunas Regional Ethical Committee (No. BE - 2-41., May 13, 2020).

Stable cranial parameters to evaluate the occlusal plane orientation in the frontal plane: a systematic review.

INTRODUCTION: A systematic review of the literature available up to October 2020 has been conducted to determine which cranial plane could represent a stable and reliable parameter to evaluate the orientation of the occlusal plane in a frontal view. EVIDENCE ACQUISITION: An electronic research was performed across the following electronic databases: PUBMED, EBSCO, SCOPUS, WoS, COCHRANE LIBRARY, SciELO, EMBASE and GOOGLE SCHOLAR. Observational studies based on imaging and anthropometry were identified, and all languages have been included. The articles were selected and analyzed by three authors independently. PICO format was adopted to analyze the studies and AXIS guidelines were used to assess the quality of evidence. EVIDENCE SYNTHESIS: We found eleven articles eligible for full-text analysis. All studies included only young subjects and analyzed the occlusal plane in relation to the frontal plane traced between the right and left tragus (Camper's and Frankfurt planes), to the interpupillary plane, and to other soft and hard tissues references. The outcomes of selected studies were various, with a low quality of evidence, and they did not allow to infer a stable cranial relation between the occlusal plane and other bone structures. CONCLUSIONS: The evidence does not support that the interpupillary plane represent a reliable parameter to evaluate the occlusal plane orientation in a frontal view; instead, the Frankfurt plane could be a much more stable reference parameter, from a morphological perspective. It is necessary to perform an observational study upon craniums to define which are the most stable cranial reference planes to determine the orientation of the occlusal plane in dentate subjects.

Is there no beauty in sexually dimorphic eyes? Facial attractiveness and White Europeans ocular morphology-Brief communication.

The link between human ocular morphology and attractiveness, especially in the context of its potential adaptive function, is an underexplored area of research. In our study, we examined the association between facial attractiveness and three sexually dimorphic measures of ocular morphology in White Europeans: the sclera size index, width-to-height ratio, and relative iris luminance. Sixty participants (30 women) assessed the attractiveness of the opposite-sex photographs of 50 men and 50 women. Our results show that in both men and women, none of the three measures was linked to the opposite sex ratings of facial attractiveness. We conclude that those ocular morphology measures may play a limited role in human mate preferences.

Pesquisa de novos pontos craniométricos para aumento da precisão em reconstrução facial forense / Ressearch of new craniometric points for more accurate facial reconstruction

A estimativa de aparência da face de uma pessoa, partindo de um crânio seco, é chamada de Reconstrução Facial Forense (RFF). Pode ser realizada de maneira digital ou manual, a partir da marcação de pontos cranianos, que possuem diferentes médias de espessura de tecido mole sobreposto. Nas reconstruções digitais o uso de tomografias computadorizadas de feixe cônico (TCFC), que nos permite obter o volume de pacientes sentados, possibilitou um avanço significativo na mensuração das médias de volume dos tecidos moles faciais. Foi desenvolvido um protocolo para medições de tecidos moles a partir de 32 pontos craniométricos (10 sagitais e 11 bilaterais). Este trabalho propõe a inserção de cinco novos pontos cranianos ao protocolo, com medidas a partir dos pontos Mentual (Ml), Supra Canino (sC), Fronto-zigomático (Fz), Ptério (Pt) e Posterior do Ramo Mandibular (prM), com o intuito de aumentar a acurácia das reconstruções. As TCFC foram manipuladas no software Horus® (LGPL 3.0) e mensuradas conforme protocolo adaptado de Beaini et al. (1), obtidas as espessuras de tecido mole a partir dos pontos craniométricos propostos. Foram estudadas 100 TCFC de brasileiros adultos (maiores de 18 anos) que disponibilizaram seus exames para utilização em pesquisas de maneira anônima e que compõe um banco de dados já estruturado e utilizado em pesquisas anteriores. Esse banco de dados contém exames de 50 indivíduos do sexo feminino e 50 do sexo masculino, separados em grupos por sexo e idade. Estatisticamente, foram aplicados testes de normalidade e a diferença entre cada grupo foi testada para obtenção das espessuras médias referentes a cada ponto craniano. Para o ponto Fz, as médias de espessura de tecidos moles foram de 4.56mm para mulheres e 5.14mm para homens. Para o ponto Ml, as médias de ETMF foram de 12.88mm para mulheres e 14.74mm para homens. No ponto prM, as médias de ETMF foram de 18.30mm para homens e 19.69mm para mulheres. No ponto Pt, as médias de ETMF foram de 11.01mm para mulheres e 13.09mm para homens. No ponto sC, as médias de ETMF foram de 10.99mm para mulheres e 12.71mm para homens. A divisão de ETMFs por sexo é justificada, concordando com parcela significativa da literatura, uma vez que quatro 10 dos cinco pontos estudados apresentaram diferenças estatísticas significativas, com as espessuras de indivíduos do sexo masculino sendo maiores que de indivíduos do sexo feminino.

Using deep learning to predict ideology from facial photographs: expressions, beauty, and extra-facial information.

Deep learning techniques can use public data such as facial photographs to predict sensitive personal information, but little is known about what information contributes to the predictive success of these techniques. This lack of knowledge limits both the public's ability to protect against revealing unintended information as well as the scientific utility of deep learning results. We combine convolutional neural networks, heat maps, facial expression coding, and classification of identifiable features such as masculinity and attractiveness in our study of political ideology in 3323 Danes. Predictive accuracy from the neural network was 61% in each gender. Model-predicted ideology correlated with aspects of both facial expressions (happiness vs neutrality) and morphology (specifically, attractiveness in females). Heat maps highlighted the informativeness of areas both on and off the face, pointing to methodological refinements and the need for future research to better understand the significance of certain facial areas.

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.

Head and facial anthropometry of the Indian population for designing a spectacle frame.

Purpose: To establish the normative data of the head and face measurements needed to design an appropriate spectacle frame for the Indian population. Methods: Indian subjects between 20 and 40 years were included in the study. Thirteen parameters were measured using the direct and indirect methods using ImageJ software. Photographs of subjects were captured in the primary gaze position, with the head turned toward the subject's right and left by 90° from the primary gaze. Results: The mean ± standard deviation of age was 27.6 ± 5.7; 55.38% were males. An independent t-test showed a significant difference in nose width (P = 0.001), inter-pupillary distance (P = 0.032), and body mass index (P = .012) between males and females. Inner inter-canthi distance (P = .265), outer inter-canthi distance (P = .509), and frontal angles (P = .536) showed no significant difference. There is a significant difference in face width compared with the other studies. The mean head width of males (154.168 ± 9.121) was wider than that of females (145.431 ± 8.923). This suggests a smaller distance between the temples of a spectacle frame for females. Conclusion: Considering the above factors, there is a need for a customized spectacle frame design providing better optics, improved cosmesis, and comfort to the wearer.