Anatomical placement of the human eyeball in the orbit--validation using CT scans of living adults and prediction for facial approximation

Developing an eyeball positioning method in the eye orbit for craniofacial identification in Korean population

We analysed the skulls and faces of Korean subjects using anthropometric methods to understand the anatomical characteristics of the eyeball and eye orbit region of Korean population and to determine the correlations between the hard and soft tissues around the eyeball and eye orbit region. In total, 82 sections in the region were measured to determine the correlations; among them, 34 showed significant differences by sex, and 6 showed significant differences by age. As the distance from the centre of the eye lens to the eye orbit is calculated as a ratio, we determined that the centre of the eye lens is located relatively on the lateral and superior position in each eye orbit in front view. Fourteen sections that could be used for craniofacial reconstruction/approximation in men and women were selected. Regression equations were derived according to the correlation of each section, and their reliabilities were verified by out of sample validation tests. Therefore, our results increase the accuracy of eyeball position determination, which would be useful for more efficient craniofacial reconstruction/approximation of the Korean population and should improve the efficiency of facial recognition.

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.

Prediction of exophthalmos by body mass index for craniofacial reconstruction: consequences for cold cases

It is inconvenient for a forensic practitioner to gather population-specific data before performing a facial reconstruction. The inconvenience may defeat the point of creating the reconstruction. The objective of this study was to evaluate a non-population-dependent method of determining exophthalmos. The protrusion of the eyeball is known to vary with the contents of the orbital cavity based on bony orbital resorption or increased or decreased fat contents, as well as according to relative eyeball size. Of use are available statistics on body mass index, and this is discussed within the context of eyeball protrusion. A weak positive correlation (0.3263) between the body mass index of the country where the study originated, and the degree of exophthalmos was found. The results suggest that eyeball protrusion rates can be established according to body mass index, and this framework may be more useful considering conventional police practices.

Determination of Mouth Width for Facial Reconstruction Based on Statistical Regression Model

INTRODUCTION

It is important to generate predictable statistical models by increasing the number of variables on the human skeletal and soft tissue structures on the face to increase the accuracy of human facial reconstructions. The purpose of this study was to determine mouth width 3-dimensionally based on statistical regression model.

MATERIAL AND METHODS

Cone-beam computed tomography scan data from 130 individuals were used to measure the horizontal and vertical dimensions of orbital and nasal structures and intercanine width. The correlation between these hard tissue variables and the mouth width was evaluated using the statistical regression model.

RESULTS

Orbital width, nasal width, and intercanine width were found to be strong predictors of the mouth width determination and were used to generate the regression formulae to find the most approximate position of the mouth.

CONCLUSION

These specific variables may contribute to improving the accuracy of mouth width determination for oral and maxillofacial reconstructions.

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.

A portrait drawing of the 17th century Korean scholar based on craniofacial reconstruction

As a technique mainly hiring in forensic investigation field to identify the descents, craniofacial reconstruction (CFR) is also used in archaeology to create the faces from ancient or medieval human remains, when there is little information about his/her appearance. Eung-Cheok Ko (1531-1605) was a writer and scholar in the mid Joseon period. In January of 2019, His mummified body was found at Gumi, Kyeonsangbuk-do, Korea. The remains were anthropologically examined, and archaeological CFR was also requested for this case. This report reveals the case's facial reconstruction process and his portrait that is drawn based on the 3-dimensional CFR result.

3-D cephalometry of the the orbit regarding endocrine orbitopathy, exophthalmos, and sex

Purpose

This study aimed at evaluating the orbital anatomy of patients concerning the relevance of orbital anatomy in the etiology of EO (endocrine orbitopathy) and exophthalmos utilizing a novel approach regarding three-dimensional measurements. Furthermore, sexual dimorphism in orbital anatomy was analyzed.

Methods

Orbital anatomy of 123 Caucasian patients (52 with EO, 71 without EO) was examined using computed tomographic data and FAT software for 3-D cephalometry. Using 56 anatomical landmarks, 20 angles and 155 distances were measured. MEDAS software was used for performing connected and unconnected t-tests and Spearman´s rank correlation test to evaluate interrelations and differences.

Results

Orbital anatomy was highly symmetrical with a mean side difference of 0.3 mm for distances and 0.6° for angles. There was a small albeit statistically significant difference in 13 out of 155 distances in women and 1 in men concerning patients with and without EO. Two out of 12 angles showed a statistically significant difference between female patients with and without EO. Regarding sex, statistically significant differences occurred in 39 distances, orbit volume, orbit surface, and 2 angles. On average, measurements were larger in men. Concerning globe position within the orbit, larger distances to the orbital apex correlated with larger orbital dimensions whereas the sagittal position of the orbital rim defined Hertel values.

Conclusion

In this study, little difference in orbital anatomy between patients with and without EO was found. Concerning sex, orbital anatomy differed significantly with men presenting larger orbital dimensions. Regarding clinically measured exophthalmos, orbital aperture anatomy is an important factor which has to be considered in distinguishing between true exophthalmos with a larger distance between globe and orbital apex and pseudoexophthalmos were only the orbital rim is retruded. Thus, orbital anatomy may influence therapy regarding timing and surgical procedures as it affects exophthalmos.

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.

Visual Depictions of Our Evolutionary Past: A Broad Case Study Concerning the Need for Quantitative Methods of Soft Tissue Reconstruction and Art-Science Collaborations

Flip through scientific textbooks illustrating ideas about human evolution or visit any number of museums of natural history and you will notice an abundance of reconstructions attempting to depict the appearance of ancient hominins. Spend some time comparing reconstructions of the same specimen and notice an obvious fact: hominin reconstructions vary in appearance considerably. In this review, we summarize existing methods of reconstruction to analyze this variability. It is argued that variability between hominin reconstructions is likely the result of unreliable reconstruction methods and misinterpretation of available evidence. We also discuss the risk of disseminating erroneous ideas about human evolution through the use of unscientific reconstructions in museums and publications. The role an artist plays is also analyzed and criticized given how the aforementioned reconstructions have become readily accepted to line the halls of even the most trusted institutions. In conclusion, improved reconstruction methods hold promise for the prediction of hominin soft tissues, as well as for disseminating current scientific understandings of human evolution in the future.

Using Computed Tomography (CT) Data to Build 3D Resources for Forensic Craniofacial Identification

Forensic craniofacial identification encompasses the practices of forensic facial approximation (aka facial reconstruction) and craniofacial superimposition within the field of forensic art in the United States. Training in forensic facial approximation methods historically has used plaster copies, high-cost commercially molded skulls, and photographs. Despite the increased accessibility of computed tomography (CT) and the numerous studies utilizing CT data to better inform facial approximation methods, 3D CT data have not yet been widely used to produce interactive resources or reference catalogs aimed at forensic art practitioner use or method standardization. There are many free, open-source 3D software packages that allow engagement in immersive studies of the relationships between the craniofacial skeleton and facial features and facilitate collaboration between researchers and practitioners. 3D CT software, in particular, allows the bone and soft tissue to be visualized simultaneously with tools such as transparency, clipping, and volume rendering of underlying tissues, allowing for more accurate analyses of bone to soft tissue relationships. Analyses and visualization of 3D CT data can not only facilitate basic research into facial variation and anatomical relationships relevant for reconstructions but can also lead to improved facial reconstruction guidelines. Further, skull and face surface models exported in digital 3D formats allow for 3D printing of custom reference models and novel training materials and modalities for practitioners. This chapter outlines the 3D resources that can be built from CT data for forensic craniofacial identification methods, including how to view 3D craniofacial CT data and modify surface models for 3D printing.

Craniofacial reconstruction of the Indus Valley Civilization individuals found at 4500-year-old Rakhigarhi cemetery

Despite academic efforts to study the Indus Valley Civilization (IVC), there have as yet been no successful attempts to unveil the IVC people's craniofacial appearance. We investigated the IVC cemetery area of Rakhigarhi site, which was estimated to be of 2273 ± 38 and 2616 ± 73 years BCE. By craniofacial reconstruction (CFR) procedure using computed tomography (CT) data of two Rakhigarhi skulls (A1 BR02 and A2 BR36), we successfully reconstructed the faces of the IVC individuals who were buried about 4500 years ago. This is the first attempt to unveil scientifically accurate representations of IVC people's actual facial morphology.

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.

Measurement of Intra-Orbital Structures in Normal Chinese Adults Based on a Three-Dimensional Coordinate System

PURPOSE OF THE STUDY

This study was to establish a three-dimensional (3D) coordinate system and to study the normal dimensions of intra-orbital structures in Chinese adults.

MATERIALS AND METHODS

One hundred and forty-five adult Chinese were selected from patients who had undergone cranio-facial computed tomography scans with diagnosis other than orbital or ocular abnormality. An orbital 3D coordinate system was built on the basis of the scans. Morphological variables of intra-orbital structures were measured in this coordinate system. Bilateral symmetry, sexual dimorphism, and correlations between variables were investigated.

RESULTS

No evident laterality was found in bilateral intra-orbital structures. The distance from the center of the eyeball to the prechiasmatic groove, the length of the optic nerve, and the thickness of rectus extraocular muscles were larger in males than in females. No sex-related difference was observed in the anteroposterior diameter of the eyeball or the exophthalmometric value. The exophthalmometric value was found to be related to the anteroposterior diameter of the eyeball, whereas the y-coordinate of the center of the eyeball had no correlation with the anteroposterior diameter of the eyeball. The optic nerve length was closely correlated to the distance from the center of the eyeball to the prechiasmatic groove.

CONCLUSIONS

The 3D coordinate system and measurement method established in this study can be applied to the standardization of orbital morphometry. The measurements obtained from normal Chinese adults may provide reference values for the morphology of intra-orbital structures.

Facial approximations: Characteristics of the eye in a South African sample

Although guidelines for facial approximations, including those for the eye, are in use in South Africa, limited data on African populations exist to confirm its validity. As precise placement of the eyes in facial approximations is of importance for facial recognition, this study tested established guidelines by measuring specific instrumental dimensions. Forty-nine cadavers from the Sefako Makgatho Health Sciences University and the University of Pretoria were dissected to determine the position of the canthi and the size and position of the eyeball in the orbit. Thirty cone beam computer tomography scans and 30 computer tomography scans from the Oral and Dental and Steve Biko Hospitals respectively were used to determine the size of the eyeball. Results from this study were compared to the published guidelines. The most prominent discrepancies included a more rectangular shape of the orbit, an oval shaped eyeball and a different position of the canthi. In African faces, the medial canthus was found to be located higher than the lateral canthus. The distance between the endocanthion and superior orbital margin was 17.7mm and the exocanthion and superior orbital margin 19.5mm. Inter-population differences may have an effect on facial approximations and its accuracy as is often demonstrated in practice. The findings of this study should be taken into consideration when designing population specific guidelines for reconstruction of the eye in South Africans of African ancestry.

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.

Three-dimensional and topographic relationships between the orbital margins with reference to assessment of eyeball protrusion

This study investigated the topographic relationships among the eyeball and four orbital margins with the aim of identifying the correlation between orbital geometry and eyeball protrusion in Koreans. Three-dimensional (3D) volume rendering of the face was performed using serial computed-tomography images of 141 Koreans, and several landmarks on the bony orbit and the cornea were directly marked on the 3D volumes. The anterior-posterior distances from the apex of the cornea to each orbital margin and between the orbital margins were measured in both eyes. The distances from the apex of the cornea to the superior, medial, inferior, and lateral orbital margins were 5.8, 5.8, 12.0, and 17.9 mm, respectively. Differences between sides were observed in all of the orbital margins, and the distances from the apex of the cornea to the superior and inferior orbital margins were significantly greater in females than in males. The anterior-posterior distance between the superior and inferior orbital margins did not differ significantly between males (6.3 mm) and females (6.2 mm). The data obtained in this study will be useful when developing practical guidelines applicable to forensic facial reconstruction and orbitofacial surgeries.

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.

Automated facial recognition and candidate list rank change of computer generated facial approximations generated with multiple eye orb positions

Expanding on research previously reported by the authors, this study further examines the recognizability of ReFace facial approximations generated with the following eye orb positions: (i) centrally within the bony eye socket, (ii) 1.0mm superior and 2.0mm lateral relative to center, and (iii) 1.0mm superior and 2.5mm lateral relative to center. Overall, 81% of the test subjects' approximation ranks improved with the use of either of the two supero-lateral eye orbs. Highly significant performance differences (p<0.01) were observed between the approximations with centrally positioned eye orbs (i) and approximations with the eye orbs placed in the supero-laterally positions (ii and iii). Noteworthy was the observation that in all cases when the best rank for an approximation was obtained with the eye orbs in position (iii), the second best rank was achieved with the eye orbs in position (ii). A similar pattern was also observed when the best rank was obtained with the eye orbs in position (ii), with 60% of the second best ranks observed in position (iii). It is argued, therefore, that an approximation constructed with the eye orbs placed in either of the two supero-lateral positions may be more effective and operationally informative than centrally positioned orbs.

Assessment of Normal Eyeball Protrusion Using Computed Tomographic Imaging and Three-Dimensional Reconstruction in Korean Adults

PURPOSE

The aim of the present study was to assess normal eyeball protrusion from the orbital rim using two- and three-dimensional images and demonstrate the better suitability of CT images for assessment of exophthalmos.

METHODS

The facial computed tomographic (CT) images of Korean adults were acquired in sagittal and transverse views. The CT images were used in reconstructing three-dimensional volume of faces using computer software. The protrusion distances from orbital rims and the diameters of eyeballs were measured in the two views of the CT image and three-dimensional volume of the face. Relative exophthalmometry was calculated by the difference in protrusion distance between the right and left sides.

RESULTS

The eyeball protrusion was 4.9 and 12.5 mm in sagittal and transverse views, respectively. The protrusion distances were 2.9 mm in the three-dimensional volume of face. There were no significant differences between right and left sides in the degree of protrusion, and the difference was within 2 mm in more than 90% of the subjects.

CONCLUSIONS

The results of the present study will provide reliable criteria for precise diagnosis and postoperative monitoring using CT imaging of diseases such as thyroid-associated ophthalmopathy and orbital tumors.

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.

Three-dimensional prediction of the human eyeball and canthi for craniofacial reconstruction using cone-beam computed tomography

An anatomical relationship between the hard and soft tissues of the face is mandatory for facial reconstruction. The purpose of this study was to investigate the positions of the eyeball and canthi three-dimensionally from the relationships between the facial hard and soft tissues using cone-beam computed tomography (CBCT). CBCT scan data of 100 living subjects were used to obtain the measurements of facial hard and soft tissues. Stepwise multiple regression analyses were carried out using the hard tissue measurements in the orbit, nasal bone, nasal cavity and maxillary canine to predict the most probable positions of the eyeball and canthi within the orbit. Orbital width, orbital height, and orbital depth were strong predictors of the eyeball and canthi position. Intercanine width was also a predictor of the mediolateral position of the eyeball. Statistically significant regression models for the positions of the eyeball and canthi could be derived from the measurements of orbit and maxillary canine. These results suggest that CBCT data can be useful in predicting the positions of the eyeball and canthi three-dimensionally.