The Validity of Ear Prediction Guidelines Used in Facial Approximation*,†,‡

Comparative Analysis of Korean Nasal Morphology Using Cone-Beam Computed Tomography

BACKGROUND/OBJECTIVES

Nasal morphology is a significant aspect of facial anatomy and is often used for forensic identification and aesthetic surgery. This study aims to compare nasal dimensions based on sex, facial index (FI), and nasal index (NI) using cone-beam computed tomography (CBCT) and 3D modeling.

METHODS

To observe differences in nasal dimensions by sex and analyze the relationships between facial shapes (FI) and nasal forms (NI), a total of 100 participants (50 males, 50 females) in their 20s were selected from Dankook University Dental Hospital. CBCT scans were performed, and 3D models were created using Mimics software (version 22.0). The measurement items included the alaria distance between (AL), the distance between N (nasion) and SN (subnasale), the distance between N (nasion) and PRN (pronasale), and the distance between SN (subnasale) and PRN (pronasale). A T-test was used for the sex-based analysis of the nasal dimensions, and the facial index- and nasal index-based nasal dimensions were analyzed using a one-way ANOVA with Scherffe's post hoc test. Additionally, all the statistical analyses were performed using SPSS software (version 23.0).

RESULTS

The results indicated that males generally have larger nasal dimensions than females. Additionally, the mesoprosopic facial type (round face) showed the largest nasal dimensions in the FI classification, while the platyrrhine nasal type (broad and short nose) exhibited the largest dimensions in the NI classification.

CONCLUSIONS

This study demonstrates that the nasal size varies significantly with sex, facial shape, and nasal form. The findings can contribute to forensic identification and provide valuable data for clinical practices in facial reconstruction and nasal surgery.

Automated reconstruction: Predictive models based on facial morphology matrices

Forensic Facial Approximation (FFA) has evolved, with techniques advancing to refine the intercorrelation between the soft-tissue facial profile and the underlying skull. FFA has become essential for identifying unknown persons in South Africa, where the high number of migrant and illegal labourers and many unidentified remains make the identification process challenging. However, existing FFA methods are based on American or European standards, rendering them inapplicable in a South African context. We addressed this issue by conducting a study to create prediction models based on the relationships between facial morphology and known factors, such as population affinity, sex, and age, in white South African and French samples. We retrospectively collected 184 adult cone beam computed tomography (CBCT) scans representing 76 white South Africans (29 males and 47 females) and 108 French nationals (54 males and 54 females) to develop predictive statistical models using a projection onto latent structures regression algorithm (PLSR). On training and untrained datasets, the accuracy of the estimated soft-tissue shape of the ears, eyes, nose, and mouth was measured using metric deviations. The predictive models were optimized by integrating additional variables such as sex and age. Based on trained data, the prediction errors for the ears, eyes, nose, and mouth ranged between 1.6 mm and 4.1 mm for white South Africans; for the French group, they ranged between 1.9 mm and 4.2 mm. Prediction errors on non-trained data ranged between 1.6 mm and 4.3 mm for white South Africans, whereas prediction errors ranging between 1.8 mm and 4.3 mm were observed for the French. Ultimately, our study provided promising predictive models. Although the statistical models can be improved, the inherent variability among individuals restricts the accuracy of FFA. The predictive validity of the models was improved by including sex and age variables and considering population affinity. By integrating these factors, more customized and accurate predictive models can be developed, ultimately strengthening the effectiveness of forensic analysis in the South African region.

Craniofacial identification standards: A review of reliability, reproducibility, and implementation

There are numerous anatomical and anthropometrical standards that can be utilised for craniofacial analysis and identification. These standards originate from a wide variety of sources, such as orthodontic, maxillofacial, surgical, anatomical, anthropological and forensic literature, and numerous media have been employed to collect data from living and deceased subjects. With the development of clinical imaging and the enhanced technology associated with this field, multiple methods of data collection have become accessible, including Computed Tomography, Cone-Beam Computed Tomography, Magnetic Resonance Imaging, Radiographs, Three-dimensional Scanning, Photogrammetry and Ultrasound, alongside the more traditional in vivo methods, such as palpation and direct measurement, and cadaveric human dissection. Practitioners often struggle to identify the most appropriate standards and research results are frequently inconsistent adding to the confusion. This paper aims to clarify how practitioners can choose optimal standards, which standards are the most reliable and when to apply these standards for craniofacial identification. This paper describes the advantages and disadvantages of each mode of data collection and collates published research to review standards across different populations for each facial feature. This paper does not aim to be a practical instruction paper; since this field encompasses a wide range of 2D and 3D approaches (e.g., clay sculpture, sketch, automated, computer-modelling), the implementation of these standards is left to the individual practitioner.

Comparison of Nasal Dimensions According to the Facial and Nasal Indices Using Cone-Beam Computed Tomography

The nasal cavity constitutes the foremost portion of the respiratory system, composed of the anterior nasal aperture, nostrils, and choanae. It has an intricate anatomical structure since it has various functions, such as heat exchange, humidification, and filtration. Accordingly, clinical symptoms related to the nose, such as nasal congestion, snoring, and nasal septal deviation, are closely linked to the complex anatomical structure of the nasal cavity. Thus, the nasal cavity stands as a paramount structure in both forensic and clinical contexts. The majority of relevant studies have performed comparisons between sexes, with studies making comparisons according to the FI and NI only and examining relative percentages. Furthermore, the nasal cavity was measured in 2D, and not 3D, in most cases. In this study, we conducted a 3D modeling and anthropometric assessment of the nasal cavity using a 3D analysis software. Furthermore, we aimed to investigate whether the size of the nasal cavity differs according to sex, facial index (FI), and nasal index (NI). We retrospectively reviewed the cone-beam computed tomography (CBCT) data of 100 participants (50 males, 50 females) aged 20-29 years who visited the dental hospital of Dankook University (IRB approval no. DKUDH IRB 2020-01-007). Our findings showed that nasal cavity sizes generally differed according to sex, FI, and NI. These findings provide implications for performing patient-tailored surgeries in clinical practice and conducting further research on the nasal cavity. Therefore, we believe that our study makes a significant contribution to the literature.

Evaluation of loci to predict ear morphology using two SNaPshot assays

Human ear morphology prediction with SNP-based genotypes is growing in forensic DNA phenotyping and is scarcely explored in Pakistan as a part of EVCs (externally visible characteristics). The ear morphology prediction assays with 21 SNPs were assessed for their potential utility in forensic identification of population. The SNaPshot™ multiplex chemistries, capillary electrophoresis methods and GeneMapper™ software were used for obtaining genotypic data. A total of 33 ear phenotypes were categorized with digital photographs of 300 volunteers. SHEsis software was applied to make LD plot. Ordinal and multinomial logistic regression was implemented for association testing. Multinomial logistic regression was executed to construct the prediction model in 90% training and 10% testing subjects. Several influential SNPs for ear phenotypic variation were found in association testing. The model based on genetic markers predicted ear phenotypes with moderate to good predictive accuracies demonstrated with the area under curve (AUC), sensitivity and specificity of predicted phenotypes. As an additional EVC, the estimated ear phenotypic profiles have the possibility of determining the human ear morphology differences in unknown biological samples found in crimes that do not result in a criminal database hit. Furthermore, this can help in facial reconstruction and act as an investigational lead.

Facial reconstruction using 3-D computerized method: A scoping review of Methods, current Status, and future developments

Facial reconstruction (otherwise known as facial approximation) is an alternative method that has been widely accepted in forensic anthropological and archaeological circumstances. This method is considered useful for creating the virtual face of a person based on skull remain. Three-dimensional (3-D) traditional facial reconstruction (known as sculpture or manual method) has been recognized for more than a century; however, it was declared to be subjective and required anthropological training. Until recently, with the progression of computational technologies, many studies attempted to develop a more appropriate method, so-called the 3-D computerized facial reconstruction. This method also relied on anatomical knowledge of the face-skull relationship, divided into semi- and automated based computational method. The 3-D computerized facial reconstruction makes it more rapid, more flexible, and more realistic to generate multiple representations of faces. Moreover, new tools and technology are continuously generating fascinating and sound research as well as encouraging multidisciplinary collaboration. This has led to a paradigm shift in the 3-D computerized facial reconstruction to a new finding and new technique based on artificial intelligence in academia. Based on the last 10-years scientific-published documents, this article aims to explain the overview of the 3-D computerized facial reconstruction and progression as well as an issue relating to future directions to encourage further improvement.

Predicting the eyebrow from the orbit using three-dimensional CT imaging in the application of forensic facial reconstruction and identification

Eyebrows are the most important facial feature in facial recognition with its shape rated to be more helpful than color or density for facial reconstruction or approximation. However, little extant research has estimated the position and morphological territory of the eyebrow from the orbit. Three-dimensional craniofacial models, produced from CT scans of 180 Koreans autopsied at the National Forensic Service Seoul Institute, were used to conduct metric analyses of subjects (125 males and 55 females) between 19 and 49 (mean 35.1) years. We employed 18 craniofacial landmarks to examine the morphometry of the eyebrow and orbit with 35 pairs of distances per subject measured between landmark and reference planes. Additionally, we used linear regression analyses to predict eyebrow shape from the orbit for every possible combination of variables. The morphology of the orbit has more influence on the position of the superior margin of the eyebrow. In addition, the middle part of the eyebrow was more predictable. The highest point of the eyebrow in female was located more medially than the male. Based on our findings, the equations for estimating the position of the eyebrow from the shape of the orbit is useful information for face reconstruction or approximation.

Towards the restoration of ancient hominid craniofacial anatomy: Chimpanzee morphology reveals covariation between craniometrics and facial soft tissue thickness

In modern humans, facial soft tissue thicknesses have been shown to covary with craniometric dimensions. However, to date it has not been confirmed whether these relationships are shared with non-human apes. In this study, we analyze these relationships in chimpanzees (Pan troglodytes) with the aim of producing regression models for approximating facial soft tissue thicknesses in Plio-Pleistocene hominids. Using CT scans of 19 subjects, 637 soft tissue, and 349 craniometric measurements, statistically significant multiple regression models were established for 26 points on the face and head. Examination of regression model validity resulted in minimal differences between observed and predicted soft tissue thickness values. Assessment of interspecies compatibility using a bonobo (Pan paniscus) and modern human subject resulted in minimal differences for the bonobo but large differences for the modern human. These results clearly show that (1) soft tissue thicknesses covary with craniometric dimensions in P. troglodytes, (2) confirms that such covariation is uniformly present in both extant Homo and Pan species, and (3) suggests that chimp-derived regression models have interspecies compatibility with hominids who have similar craniometric dimensions to P. troglodytes. As the craniometric dimensions of early hominids, such as South African australopithecines, are more similar to P. troglodytes than those of H. sapiens, chimpanzee-derived regression models may be used for approximating their craniofacial anatomy. It is hoped that the results of the present study and the reference dataset for facial soft tissue thicknesses of chimpanzees it provides will encourage further research into this topic.

Forensic Recreation and Visual Representation of Greek Orthodox Church Saint Eftychios of Crete

Facial reconstruction is employed in medical science and archaeology. Though quite popular as anthropological method, it has not so far been used in the orthodox ecclesiastical tradition. This work presents the facial reconstruction of St Eftychios of Crete, who lived between the ninth and tenth centuries. Computed tomography and reverse engineering methods were employed to complete the task. Reconstruction of the mandible and the missing left zygomatic arch was implemented following the Sassouni method. The American method was followed for the soft tissues, with clay deposition of appropriate thickness, on the surface of the skull model. The eyes, nose, and lips were added based on the dimensions of the underlying bone structures. Long hair and beard were added, according to the classic Byzantine tradition pattern of the time period. The final bust developed was then digitized, using a 3D non-contact laser scanner. The 3D geometry produced was employed to produce a mold with vacuum casting techniques. This mold provides the ability to produce copies of the bust, if needed. At the same time, a realistic 3D representation of the Saint's bust was developed, with the aid of special software, in order to compare the traditional forensic reconstruction to the pure digital one. This work is the first case of a Saint's facial reconstruction in the Orthodox Church. The facial reconstruction process, with all the limitations considered, offers the ability to present a realistic aspect of a Greek Orthodox Church Saint, in a form that is easily accessible. Both physical and digital facial reconstruction processes were based on scientific data, so they were as accurate as possible, considering that the mandible was missing in the skull. The facial reconstruction was entirely implemented in Greece creating the basis for similar work in the future. The final bust developed was donated to the Odigitria Monastery, to be exhibited to its visitors.

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.

An overview of the latest developments in facial imaging

Facial imaging is a term used to describe methods that use facial images to assist or facilitate human identification. This pertains to two craniofacial identification procedures that use skulls and faces-facial approximation and photographic superimposition-as well as face-only methods for age progression/regression, the construction of facial graphics from eyewitness memory (including composites and artistic sketches), facial depiction, face mapping and newly emerging methods of molecular photofitting. Given the breadth of these facial imaging techniques, it is not surprising that a broad array of subject-matter experts participate in and/or contribute to the formulation and implementation of these methods (including forensic odontologists, forensic artists, police officers, electrical engineers, anatomists, geneticists, medical image specialists, psychologists, computer graphic programmers and software developers). As they are concerned with the physical characteristics of humans, each of these facial imaging areas also falls in the domain of physical anthropology, although not all of them have been traditionally regarded as such. This too offers useful opportunities to adapt established methods in one domain to others more traditionally held to be disciplines within physical anthropology (e.g. facial approximation, craniofacial superimposition and face photo-comparison). It is important to note that most facial imaging methods are not currently used for identification but serve to assist authorities in narrowing or directing investigations such that other, more potent, methods of identification can be used (e.g. DNA). Few, if any, facial imaging approaches can be considered honed end-stage scientific methods, with major opportunities for physical anthropologists to make meaningful contributions. Some facial imaging methods have considerably stronger scientific underpinnings than others (e.g. facial approximation versus face mapping), some currently lie entirely within the artistic sphere (facial depiction), and yet others are so aspirational that realistic capacity to obtain their aims has strongly been questioned despite highly advanced technical approaches (molecular photofitting). All this makes for a broad-ranging, dynamic and energetic field that is in a constant state of flux. This manuscript provides a theoretical snapshot of the purposes of these methods, the state of science as it pertains to them, and their latest research developments.

How tight is the relationship between the skeletal and soft-tissue facial profile: A geometric morphometric analysis of the facial outline

Correlations between facial bony structures and soft facial features are fundamental for facial approximation methods The purpose of this study was to assess the strength of the association between craniofacial shape and the shape of the soft-tissue profile and to determine the extent to which it might be possible to predict the latter from the former. Soft-tissue and skeletal facial profile curves were extracted from 86 lateral head cephalograms of a recent Central European population (52 males and 34 females, aged between 19 and 43 years), divided into five parts, segmented automatically and evaluated using geometric morphometrics. The magnitude of the hard-soft shape association was assessed by principal component analysis and subsequent multiple linear regression (Halazonetis, 2007), by partial least square analysis (PLS) (Rohlf and Corti, 2000) and the RV coefficient (Klingenberg, 2009). The greatest amount of association between the skeletal contour and overlying soft tissues was exhibited by the region of the forehead (predictive power: 95.1%, RV=0.91, correlation for PLS1 r=0,96), followed by the region of the nasal root (predictive power: 40.2%, RV=0.42, r_PLS1=0.72) and the lower lip and chin (predictive power: 37.3%, RV=0.41, r_PLS1=0.65). The smallest statistically significant covariation was displayed by the upper lip and the maxilla (predictive power: 9.6%, RV=0.14, r_PLS1=0.43). The shape covariation between the nasal bridge and the tip and lateral border of the nasal aperture was found to be statistically insignificant (predictive power: 5.8%, RV=0.05, r_PLS1=0.26). Shape covariation was visualized and described by thin-plate spine grids. These findings correspond with the observation that the shape of the nasal profile and the upper lip contour are difficult to reconstruct or predict reliably in facial approximations. It seems that the shape of soft tissues might not follow underlying structures as closely as expected.

Eyeball Position in Facial Approximation: Accuracy of Methods for Predicting Globe Positioning in Lateral View

This study measured the accuracy of traditional and validated newly proposed methods for globe positioning in lateral view. Eighty lateral head cephalograms of adult subjects from Central Europe were taken, and the actual and predicted dimensions were compared. The anteroposterior eyeball position was estimated as the most accurate method based on the proportion of the orbital height (SEE = 1.9 mm) and was followed by the "tangent to the iris method" showing SEE = 2.4 mm. The traditional "tangent to the cornea method" underestimated the eyeball projection by SEE = 5.8 mm. Concerning the superoinferior eyeball position, the results showed a deviation from a central to a more superior position by 0.3 mm, on average, and the traditional method of central positioning of the globe could not be rejected as inaccurate (SEE = 0.3 mm). Based on regression analyzes or proportionality of the orbital height, the SEE = 2.1 mm.

Critical issues in the historical and contemporary development of forensic anthropology in Australia: An international comparison

The aim of this brief critical qualitative analysis is to examine the development of forensic anthropology in Australia, at a time of significant change in the discipline. It will briefly summarise its historical establishment, making comparative reference to other regions-particularly the United Kingdom and United States, and the influence of the Bali Bombings of 2002, Indian Ocean earthquake and tsunami of 2004 and Black Saturday Bushfires of 2009. The analysis goes on to consider key factors in research in forensic anthropology in the United States, and the development of standards and regulation in the US and UK. The significance of research in post-mortem diagenesis in Brazil-a country sharing aspects of climate, soil types and demography with Australia-is also considered, as well as the significance of patterns of casework encountered in Australia compared with those of other jurisdictions. While forensic anthropology as a discipline has grown remarkably in recent years, this analysis suggests that research and training tailored to the specific pattern of casework encountered in Australia is now essential to support the development of national standards in science, education, and professional regulation. The significance of the establishment of the first taphonomy research facility outside of the US-the Australian Facility for Taphonomic Experimental Research-is briefly considered with reference to what this facility may offer to the development of forensic anthropology in Australia.

Comparison Among Manual Facial Approximations Conducted by Two Methodological Approaches of Face Prediction

This study verified the difference between two methods of forensic facial approximation (FFA) regarding recognition and resemblance rates. Three-dimensional models of skulls were obtained from computerized tomography (CT) scans of two subjects (targets). Two manual FFAs were performed for each target, by applying two different guidelines for the facial structures (what we called "American method" (AM) and "Combined method" (CM)). Unfamiliar assessors evaluated the sculptures by recognition and resemblance tests. The AM was that which allowed more correct responses of recognition and higher resemblance's scores for the male target (p < 0.001). Regarding guidelines for modeling characteristics of the face, the ones that are practical and easily performed for sculptures, such as the length of the anterior nasal spine multiplied by 3 for nose prediction, may offer better results in terms of resemblance.

The unfamiliar face effect on forensic craniofacial reconstruction and recognition

Previous research into the reliability of forensic craniofacial reconstruction (CFR) has focused primarily on the accuracy of reconstructed faces from European or African ancestry skulls. Moreover, the recognition of CFR in relation to the experience and ancestry of the practitioners and the assessors has not been previously considered. The cross-race effect is a recognised phenomenon in psychology studies, where familiar ancestry faces are recognised more readily than unfamiliar ancestry faces, but there is a paucity of research addressing the relationship between the accuracy of reconstructed faces and the familiarity with this ancestry by the practitioners/assessors. The aims of this research were to investigate whether 'unfamiliar-race effect' has any influence on the accuracy of CFR and to evaluate how much the correct recognition rate of CFR is affected by the cross-race effect. Eight CFRs from three ancestry groups were produced by experienced practitioners in order to explore the aims. The results demonstrated that practitioners produced more recognisable CFRs using skulls from a familiar ancestry than skulls from unfamiliar ancestries.

Feature proportion accuracy of hand-drawn facial approximation

Several studies have investigated the predictive accuracy of facial approximation methods for individual facial features, but few have investigated the ability of these methods to accurately predict the relative dimensions of these features. Photographs of 10 skulls from the William M. Bass Donated Skeletal Collection were used to create hand-drawn facial approximations following the guidelines presented in Taylor (2001). Measurements of the eyes, nose, and mouth were made and converted to ratios for comparison to their corresponding antemortem photographs. Potential error introduced by angulation in the antemortem photographs was assessed by finding similar ratio values for volunteers who were photographed at a series of angles. Eye measurements were distorted when individuals were turned 30 to 70° away from the camera. However, all antemortem photographs displayed individuals turned 30° or less from the camera. Wilcoxon signed rank tests revealed no significant differences between the hand-drawn approximations and the antemortem photograph measurements values for all feature relationships except for the eye width to iris diameter ratio, likely because the Taylor (2001) method does not reference the underlying bone when approximating the size and appearance of the eye.

Forensic facial approximation assessment: can application of different average facial tissue depth data facilitate recognition and establish acceptable level of resemblance?

Facial soft tissue thicknesses (FSTT) are important guidelines for modeling faces from skull. Amid so many FSTT data, Forensic artists have to make a subjective choice of a dataset that best meets their needs. This study investigated the performance of four FSTT datasets in the recognition and resemblance of Brazilian living individuals and the performance of assessors in recognizing people, according to sex and knowledge on Human Anatomy and Forensic Dentistry. Sixteen manual facial approximations (FAs) were constructed using three-dimensional (3D) prototypes of skulls (targets). The American method was chosen for the construction of the faces. One hundred and twenty participants evaluated all FAs by means of recognition and resemblance tests. This study showed higher proportions of recognition by FAs conducted with FSTT data from cadavers compared with those conducted with medical imaging data. Targets were also considered more similar to FAs conducted with FSTT data from cadavers. Nose and face shape, respectively, were considered the most similar regions to targets. The sex of assessors (male and female) and the knowledge on Human Anatomy and Forensic Dentistry did not play a determinant role to reach greater recognition rates. It was possible to conclude that FSTT data obtained from imaging may not facilitate recognition and establish acceptable level of resemblance. Grouping FSTT data by regions of the face, as proposed in this paper, may contribute to more accurate FAs.

Vertical Lip Position and Thickness in Facial Reconstruction: A Validation of Commonly Used Methods for Predicting the Position and Size of Lips

This study examined several methods used to estimate oral fissure position, lip margin position, and lip thickness recommended by Angel, George, Lebedinskaya, Taylor, Wilkinson et al., Balueva and Veselovskaya. A sample of 86 lateral head cephalograms of adult subjects from central Europe were measured and the actual and predicted dimensions were compared. The best estimation for oral fissure position was "opposite the lower ¾ mark of maxillary incisors" (error of 1.3 mm). Upper lip margin was predicted best by "upper ¼ mark of maxillary incisors" (error of 1.7 mm), and lower lip margin by "cementum-enamel junction of mandibular incisors" (error of 2.3 mm). The regression equations of Wilkinson et al. displayed least error (1.3 mm and 1.8 mm, respectively) for upper and lower lip thickness, and method of George (error of 3.4 mm) for total lip thickness.

Anthropological facial approximation in three dimensions (AFA3D): computer-assisted estimation of the facial morphology using geometric morphometrics

This study presents Anthropological Facial Approximation in Three Dimensions (AFA3D), a new computerized method for estimating face shape based on computed tomography (CT) scans of 500 French individuals. Facial soft tissue depths are estimated based on age, sex, corpulence, and craniometrics, and projected using reference planes to obtain the global facial appearance. Position and shape of the eyes, nose, mouth, and ears are inferred from cranial landmarks through geometric morphometrics. The 100 estimated cutaneous landmarks are then used to warp a generic face to the target facial approximation. A validation by re-sampling on a subsample demonstrated an average accuracy of c. 4 mm for the overall face. The resulting approximation is an objective probable facial shape, but is also synthetic (i.e., without texture), and therefore needs to be enhanced artistically prior to its use in forensic cases. AFA3D, integrated in the TIVMI software, is available freely for further testing.