Sex determination by discriminant function analysis of the mandible

An open-source, three-dimensional growth model of the mandible

The available reference data for the mandible and mandibular growth consists primarily of two-dimensional linear or angular measurements. The aim of this study was to create the first open-source, three-dimensional statistical shape model of the mandible that spans the complete growth period. Computed tomography scans of 678 mandibles from children and young adults between 0 and 22 years old were included in the model. The mandibles were segmented using a semi-automatic or automatic (artificial intelligence-based) segmentation method. Point correspondence among the samples was achieved by rigid registration, followed by non-rigid registration of a symmetrical template onto each sample. The registration process was validated with adequate results. Principal component analysis was used to gain insight in the variation within the dataset and to investigate age-related changes and sexual dimorphism. The presented growth model is accessible globally and free-of-charge for scientists, physicians and forensic investigators for any kind of purpose deemed suitable. The versatility of the model opens up new possibilities in the fields of oral and maxillofacial surgery, forensic sciences or biological anthropology. In clinical settings, the model may aid diagnostic decision-making, treatment planning and treatment evaluation.

Classification performance of the Sella-Tunis et al. (2017) sex estimation method in Czech population: different posterior probability threshold approaches

In this study we tested classification performance of a sex estimation method from the mandible originally developed by Sella-Tunis et al. (2017) on a heterogeneous Israeli population. Mandibular linear dimensions were measured on 60 CT scans derived from the Czech living population. Classification performance of Israeli discriminant functions (DFs-IL) was analyzed in comparison with calculated Czech discriminant functions (DFs-CZ) while different posterior probability thresholds (currently discussed in the forensic literature) were employed. Our results comprehensively illustrate sensitivity of different discriminant functions to population differences in body size and degree of sexual dimorphism. We demonstrate that the error rate may be biased when presented per posterior probability threshold. DF-IL 1 showed least sensitivity to population origin and fulfilled criteria of sufficient classification performance when applied on the Czech sample with a minimum posterior probability threshold of 0.88 reaching overall accuracy ≥ 95%, zero sex bias, and 80% of classified individuals. The last parameter was higher in DF-CZ 1 which was the main difference between those two DFs suggesting relatively low dependance on population origin. As the use of population-specific methods is often prevented by complicated assessment of population origin, DF-IL 1 is a candidate for a sufficiently robust method that could be reliably applied outside the reference sample, and thus, its classification performance deserves further testing on more population samples.

Shape variation and sex differences of the adult human mandible evaluated by geometric morphometrics

In cases of osseous defects, knowledge of the anatomy, and its age and sex-related variations, is essential for reconstruction of normal morphology. Here, we aimed at creating a 3D atlas of the human mandible in an adult sample using dense landmarking and geometric morphometrics. We segmented 50 male and 50 female mandibular surfaces from CBCT images (age range: 18.9-73.7 years). Nine fixed landmarks and 510 sliding semilandmarks were digitized on the mandibular surface, and then slid by minimizing bending energy against the average shape. Principal component analysis extracted the main patterns of shape variation. Sexes were compared with permutation tests and allometry was assessed by regressing on the log of the centroid size. Almost 49 percent of shape variation was described by the first three principal components. Shape variation was related to width, height and length proportions, variation of the angle between ramus and corpus, height of the coronoid process and inclination of the symphysis. Significant sex differences were detected, both in size and shape. Males were larger than females, had a higher ramus, more pronounced gonial angle, larger inter-gonial width, and more distinct antegonial notch. Accuracy of sexing based on the first two principal components in form space was 91 percent. The degree of edentulism was weakly related to mandibular shape. Age effects were not significant. The resulting atlas provides a dense description of mandibular form that can be used clinically as a guide for planning surgical reconstruction.

Sex estimation research trends in forensic anthropology between 2000 and 2022 in five prominent journals

In forensic anthropology, osteological sex estimation methods are continuously reevaluated and updated to improve classification accuracies. Therefore, to gain a comprehensive understanding of recent trends in sex estimation research in forensic anthropology, a content analysis of articles published between 2000 and 2022 in Forensic Science International, the Journal of Forensic Sciences, the International Journal of Legal Medicine, the American Journal of Biological Anthropology, and Forensic Anthropology, was performed. The main goals of this content analysis were to (1) examine trends in metric versus morphological research, (2) examine which areas of the skeleton have been explored, (3) examine which skeletal collections and population affinities have been most frequently utilized, and (4) determine which statistical methods were commonly implemented. A total of 440 articles were coded utilizing MAXQDA and the resulting codes were exported for analysis. Statistical analyses were conducted utilizing the Cochran-Armitage and Jonckheere-Terpstra tests for trends, as well as Fisher-Freeman-Halton tests. The results demonstrate that sex estimation research published in these journals has prioritized metric over morphological methods. Further, the most utilized skeletal regions continue to be the skull and pelvis, while the most popular classification statistics continue to be discriminant function analysis and logistic regression. This study also demonstrates that a substantial portion of research has been conducted utilizing U.S. and Europe-based collections and limited populations. Based on these results, future sex estimation research must continue exploring the use of long bones and other postcranial elements, testing newer methods of analysis, as well as developing population-inclusive methods.

The influence of biological relatedness on sexual dimorphism and sex classification based on external morphology of the frontal bone

The most significant sexual differences in the human skull are located in the upper third of the face (the frontal bone), which is a useful research object, mainly in combination with virtual anthropology methods. However, the influence of biological relatedness on sexual dimorphism and frontal bone variability remains unknown. This study was directed at sexual difference description and sex classification using the form and shape of the external surface of the frontal bones from a genealogically documented Central European osteological sample (nineteenth to twentieth centuries). The study sample consisted of 47 cranial CT images of the adult members of several branches of one family group over 4 generations. Three-dimensional virtual models of the frontal bones were analyzed using geometric morphometrics and multidimensional statistics. Almost the entire external frontal surface was significantly different between males and females, especially in form. Significant differences were also found between this related sample and an unrelated one. Sex estimation of the biologically related individuals was performed using the classification models developed on a sample of unrelated individuals from the recent Czech population (Čechová et al. in Int J Legal Med 133: 1285 1294, 2019), with a result of 74.46% and 63.83% in form and shape, respectively. Failure of this classifier was caused by the existence of typical traits found in the biologically related sample different from the usual manifestation of sexual dimorphism. This can be explained as due to the increased degree of similarity and the reduction of variability in biologically related individuals. The results show the importance of testing previously published methods on genealogical data.

The Role of an Endodontist in Victim Identification: A Narrative Review on Forensic Endodontics

This narrative review highlights the role of endodontists and the significance of various dental tools in forensic dentistry. An online search was conducted in peer-reviewed journals, including MEDLINE (Ovid), PubMed, Web of Science, Scopus, and Google Scholar databases, to retrieve studies regarding "the role of an endodontist in victim identification using different tools". The searches used controlled vocabulary and free-text terms. Articles written in English and published from 1923 to 2023 were selected. An essential stage in forensic dentistry is dental identification of the dead person and is regarded as an initial step for both judicial and humanitarian purposes if fingerprint records are missing or the remains have undergone significant changes. Endodontists should be aware of all available dental tools that aid in identification. The four fundamental tools for identification are dental radiographs, hard and soft dental structures, and dental materials. Dental radiographs provide a substantial nondestructive record for estimating age and sex. Moreover, maxillofacial hard and soft structures provide important tools for individual identification as they are considered the strongest structures in the human body and can withstand severe chemical and temperature changes. In addition, endodontic and restorative materials can be identified under different conditions and serve as excellent forensic identification measures.

Mandibular Ramus: An Indicator of Gender and Chronological Age - A Digital Radiographic Study

Background: The determination of sex and age of individual is important in forensic practice and medico legal purposes. Mandible may play a vital role in sex estimation as it is the most dimorphic bone of skull that often is recovered intact. The present study was conducted to evaluate the reliability of mandibular measurements in gender determination and age estimation as seen on digital panoramic radiographs. Aims and Objectives: The aim of the study was to evaluate and compare seven parameters of the mandibular ramus obtained from digital orthopantomographs, and to assess the usefulness of these parameters as aids in gender and age estimation. The objectives were: 1. To assess:-Maximum ramus breadth in mm, Minimum ramus width in mm, Projective height of ramus in mm, Maximum height of the ramus in mm, Maximum coronoid height in mm, Gonial width in mm and Bigonial angle in degrees, 2. To correlate each of these seven variables with the age of the patient, and 3. To compare these seven parameters between males and females. Materials and Methods: OPGs of 500 patients satisfying inclusion and exclusion criteria selected from the Dept. of Oral Medicine and Radiology, Govt. Dental College, Kottayam, were being studied. Permission from the concerned departments was taken. The measurements were made on this radiograph using GIMP 2.8 Software. Results: All the parameters were found to show statistically significant difference between males and females. After performing logistic regression, an equation was formulated to determine gender from the parameters that were statistically significant in regression analysis. The cut off was set at 0.5. Values above the cut off value were interpreted as males and values below the cut off were interpreted as females. The overall accuracy of sex determination at this cut off value from this method was 73.9%. Significant correlation was not noted between the mandibular parameters and age of the individual. Conclusion: It can be concluded that the mandibular ramus can be considered as a valuable tool in gender estimation since it possesses resistance to damage and disintegration processes. Nevertheless, the age of the individual cannot be determined using this method.

Automated description of the mandible shape by deep learning

PURPOSE

The shape of the mandible has been analyzed in a variety of fields, whether to diagnose conditions like osteoporosis or osteomyelitis, in forensics, to estimate biological information such as age, gender, and race or in orthognathic surgery. Although the methods employed produce encouraging results, most rely on the dry bone analyses or complex imaging techniques that, ultimately, hamper sample collection and, as a consequence, the development of large-scale studies. Thus, we proposed an objective, repeatable, and fully automatic approach to provide a quantitative description of the mandible in orthopantomographies (OPGs).

METHODS

We proposed the use of a deep convolutional neural network (CNN) to localize a set of landmarks of the mandible contour automatically from OPGs. Furthermore, we detailed four different descriptors for the mandible shape to be used for a variety of purposes. This includes a set of linear distances and angles calculated from eight anatomical landmarks of the mandible, the centroid size, the shape variations from the mean shape, and a group of shape parameters extracted with a point distribution model.

RESULTS

The fully automatic digitization of the mandible contour was very accurate, with a mean point to the curve error of 0.21 mm and a standard deviation comparable to that of a trained expert. The combination of the CNN and the four shape descriptors was validated in the well-known problems of forensic sex and age estimation, obtaining 87.8% of accuracy and a mean absolute error of 1.57 years, respectively.

CONCLUSION

The methodology proposed, including the shape model, can be valuable in any field that requires a quantitative description of the mandible shape and a visual representation of its changes such as clinical practice, surgery management, dental research, or legal medicine.

Full Facial Allotransplantation Including the Temporomandibular Joints: A Radiologic and Anatomical Cadaveric Study

BACKGROUND

Facial allotransplantation including the temporomandibular joints may improve the functional outcomes in face transplant candidates who have lost or damaged this joint.

METHODS

Linear and angular measurements were taken in 100 dry skulls and mandibles and in 100 three-dimensionally-reconstructed facial computed tomographic scans to determine the variability of the temporomandibular joint, glenoid fossa, and mandible. A vascular study was performed in six fresh cadaveric heads, followed by harvest of the face allograft in three heads. Next, four heads were used for mock transplantation (two donors and two recipients). The full facial allograft included four different segments: a Le Fort III, a mandibular tooth-bearing, and two condyle and temporomandibular joint-bearing segments. Statistical analysis was performed using SAS software.

RESULTS

In only one-third of the skulls, the condylar shape was symmetric between right and left sides. There was a wide variability in the condylar coronal (range, 14.3 to 23.62 mm) and sagittal dimensions (range, 5.64 to 10.96 mm), medial intercondylar distance (range, 66.55 to 89.91 mm), and intercondylar angles (range, 85.27 to 166.94 degrees). This high variability persisted after stratification by sex, ethnicity, and age. The temporomandibular joint was harvested based on the branches of the superficial temporal and maxillary arteries. The design of the allograft allowed fixation of the two condyle and temporomandibular joint-bearing segments to the recipient skull base, preserving the articular disk-condyle-fossa relationship, and differences were adjusted at the bilateral sagittal split osteotomy sites.

CONCLUSION

Procurement and transplantation of a temporomandibular joint-containing total face allograft is technically feasible in a cadaveric model.

Sex estimation in the cranium and mandible: a multislice computed tomography (MSCT) study using anthropometric and geometric morphometry methods

INTRODUCTION

The purpose of this study was to analyze the respective contribution of the skull and mandible to sex estimation in an entire cranium using metric and geometric morphometric methods and multislice computed tomography (MSCT) analysis.

MATERIALS

The study sample comprised 120 individuals aged 23 to 84 years and divided into three groups (whole sample and over or under 40 years of age).

METHODS

Forty-eight osteometric landmarks were positioned using Osirix®, 34 for the cranium and 14 for the mandible. The data were analyzed using univariate analyses and logistic regression using backward stepwise selection with cross-validation of the classification results. Generalized procrustes analysis (GPA) was used, and Goodall's F test and Mahalanobis D² matrices allowed an assessment of statistical significance.

RESULTS

The classification accuracy of cranium models ranged from 87% to 88.3%, and from 68% to 81.4% for the mandibular models. With geometric morphometry, accuracy was of 94-100% for the cranium and 84.2% for the mandible.

DISCUSSION

We conclude that the mandible had a higher accuracy rate for individuals over 40 years than individuals under 40 years of age, although the accuracy of geometric morphometry did not differ significantly between the age groups. The cranium, however, presented greater predictability for all the parameters assessed.

Examination of new parameters for sex determination of mandible using Japanese computer tomography data

OBJECTIVE

In the field of forensic science, sex discrimination of skeletons is an important identification item for personal identification. The individual sex discrimination method using skeletons includes a determination method using measurement values and a macroscopic form observation method. Both methods have advantage and disadvantage. In this study, we used the homologous model technique and principal component (PC) analysis to determine gender difference from morphology of the mandible.

METHODS AND MATERIALS

45 patients (23 males and 22 females) of CT imaging for tooth extraction from January 2018 to March 2019 at department of oral surgery, Osaka Medical College. The mean age was 43.1 ± 14.6. Patients with less than 14 remaining teeth were excluded because the number of remaining teeth may affect the shape of the mandible. 3D images were constructed, and 20 landmarks plotting on the 3D model surfaces. We generated template models of the mandible consisting of approximately 8434 polygons. The template model automatically fitted into the individually scanned point cloud of the mandible by minimising external and internal energy functions. As described above, the mandibles were constructed for each sample by using the Homologous Body Modeling software (HBM, Digital Human Technology, Inc.) and the mHBM-Rugle (Medic Engineering Corporation). The mandibles were analysed using the PCA.

RESULTS

The contribution of the most important PC was found to be 27.2%. 12 PCs explained over 75% of the total variance. That is, it was able to express 75% or more of the mandible expression with 12 PCs. A significant difference between male and female was observed in the first PCs (Wilcoxon test, p < 0.05). Visualising the result of the first PC showed that the mandibular branch of male was larger than that of female, and the mandible angle was overhanging outside.

CONCLUSION

This method is a combination of the determination method using the previous measurement values and the determination using macroscopic observation, and is considered to be innovative method.

Dilemma of Gonial Angle in Sex Determination: Sexually Dimorphic or Not?

BACKGROUND AND AIM

The determination of sex from human remains has a crucial role in forensic anthropology. It has been known that the mandible has several useful traits for sex determination. The gonial angle, which is one of them, has been evaluated by forensic practitioners to identify sexual dimorphism with morphologic and metrical analyses. However, there are opposing approaches on the sexual dimorphism of the gonial angle in the literature, which contradict each other. There are also some other studies asserting that it cannot be employed in sex determination. The purpose of this study is first to figure out the reason for this dilemma and then establish the significance of the gonial angle in sex determination in a white sample.

METHODS

Computed tomography scans were obtained from 300 adults (150 males and 150 females), which were divided into 3 age groups (20-39, 40-59, 60-80 years). The gonial angle, which is formed by 2 lines: (1) between the most posterior point of the mandibular condyle and the gonion and (2) between the most inferior point of the mandibular symphysis and gonion, was measured on computed tomography scans. In order to observe differences among the 3 age groups, the collected data were analyzed using 1-way analysis of variance followed by a least significant difference post hoc test. Two-way analysis of variance was used to compare sex differences in each age group.

DISCUSSION

It is suggested that the probable reason of this dilemma is the unsubtle samples of the researches. Categorizing the sample into age groups with statistically sufficient number makes the data more valuable in terms of examining the differences related to sexual dimorphism. This study also reported that males showed slightly smaller gonial angle values than those of females in all age groups. No statistically significant difference was observed in the gonial anthropometric values for middle age groups (20-39 and 40-59 years), whereas it shows statistically sexual dimorphism for senior adult group (60-80 years). However, the results revealed that the gonial angle is not a particularly good indicator to identify the sex from the cranium and should not be used as a sole criterion.

Age and Gender Differences of the Frontal Bone: A Computed Tomographic (CT)-Based Study

BACKGROUND

Age-related changes of the frontal bone in both males and females have received limited attention, although understanding these changes is crucial to developing the best surgical and nonsurgical treatment plans for this area.

OBJECTIVES

To investigate age-related and gender-related changes of the forehead.

METHODS

Cranial computed tomographic images from 157 Caucasian individuals were investigated (10 males and 10 females from each of the following decades: 20-29 years, 30-39 years, 40-49 years, 50-59 years, 60-69 years, 70-79 years, 80-89 years, and of 8 males and 9 females aged 90-98 years). Frontal bone thickness and forehead distance measurements were carried out to analyze age and gender differences.

RESULTS

With increasing age, the size of a male forehead reduces until no significant differences to a female forehead is present at old age (P = 0.307). The thickness of the frontal bone of the lower forehead (≤4 cm cranial to the nasal root) increased slightly in both genders with increasing age. In the upper forehead (≥4 cm cranial to the nasal root), frontal bone thickness decreased significantly (P = 0.002) in males but showed no statistically significant change in thickness in females (P = 0.165).

CONCLUSIONS

The shape of the frontal bone varies in young individuals of different genders and undergoes complex changes with age because of bone remodeling. Understanding these bony changes, in addition to those in the soft tissues, helps physicians choose the best surgical and nonsurgical treatment options for the forehead.

LEVEL OF EVIDENCE: 4

Cephalometric studies of the mandible, its masticatory muscles and vasculature of growing Göttingen Minipigs-A comparative anatomical study to refine experimental mandibular surgery

Over many decades, the Göttingen Minipig has been used as a large animal model in experimental surgical research of the mandible. Recently several authors have raised concerns over the use of the Göttingen Minipig in this research area, observing problems with post-operative wound healing and loosening implants. To reduce these complications during and after surgery and to improve animal welfare in mandibular surgery research, the present study elucidated how comparable the mandible of minipigs is to that of humans and whether these complications could be caused by specific anatomical characteristics of the minipigs' mandible, its masticatory muscles and associated vasculature. Twenty-two mandibular cephalometric parameters were measured on CT scans of Göttingen Minipigs aged between 12 and 21 months. Ultimately, we compared this data with human data reported in the scientific literature. In addition, image segmentation was used to determine the masticatory muscle morphology and the configuration of the mandibular blood vessels. Compared to data of humans, significant differences in the mandibular anatomy of minipigs were found. Of the 22 parameters measured only four were found to be highly comparable, whilst the others were not. The 3D examinations of the minipigs vasculature showed a very prominent deep facial vein directly medial to the mandibular ramus and potentially interfering with the sectional plane of mandibular distraction osteogenesis. Damage to this vessel could result in inaccessible bleeding. The findings of this study suggest that Göttingen Minipigs are not ideal animal models for experimental mandibular surgery research. Nevertheless if these minipigs are used the authors recommend that radiographic techniques, such as computed tomography, be used in the specific planning procedures for the mandibular surgical experiments. In addition, it is advisable to choose suitable age groups and customize implants based on the mandibular dimensions reported in this study.

Assessment of the Effect of Dimensions of the Mandibular Ramus and Mental Foramen on Age and Gender Using Digital Panoramic Radiographs: A Retrospective Study

Background

A retrospective study is conducted to evaluate the mental foramen size and ramus height using digital panoramic radiograph to see if these parameters could be used to determine a correlation with age and gender in dentate subjects and to show its relevance in forensic odontology.

Aim

To determine if there is an interrelation between two mandibular parameters (mental foramen, ramus height) in gender and age assessment.

Materials and Methods

Five hundred and forty-five high-quality radiographs of patients aged 20 years and above were selected to see superior and inferior aspects of the mental foramen and the ramus height.

Statistical Analysis

Data obtained were analyzed using the SPSS 20 version software. The mean and standard deviations were calculated for each clinical parameter, and one-way ANOVA statistical test of significance was used to compare superior and inferior aspects of mental foramen and ramus height with age groups and gender for both right and left sides. Statistical significance was set at P < 0.05.

Results

Highly significant relationship was observed, and it was also found that as the age advances, the mental foramen and ramus height increase on both the right and left sides; whereas the mental foramen and ramus height increase among males as compared to females on both the right and left sides.

Conclusion

There were significant changes in the dimensions of mental foramen and ramus height as age advances. The results concluded that ramus height and the mental foramen can be used effectively in the identification of gender using digital panoramic radiography.

Dimensions around the nutrient foramina of the tibia and fibula in the estimation of sex

Sex estimation from skeletal remains is one of the key components in establishing a biological profile and consequent identification of an individual in a forensic and medico-legal practice. The use of dimensions around the nutrient foramen in instances where long bones may be fragmented and damaged is of benefit due to the fact that the nutrient foramen is easily identifiable and may be preserved on the shaft of long bones. This study is an investigation of the usefulness of various measurements around the nutrient foramen of the tibia and fibula of South Africans in an attempt to develop osteometric standards for sex estimation. The sample included 206 tibiae and 204 fibulae of South African Africans (SAA) and South African whites (SAW) procured from the Raymond A. Dart Collection of Human Skeletons based at the University of the Witwatersrand. Sex was correctly classified for the tibia with an accuracy ranging between 79-82% in SAA and 84-88% in SAW, with the circumference at the level of the nutrient foramen as the single best predictor of sex in both populations. An accuracy ranging from 69 to 74% in SAA and 70-77% in SAW was observed for the combined measurements on the fibula. The current study confirms the usefulness of measurements around the nutrient foramen of the tibia in the assignment of sex. However functions of the fibula generally performed poorly and should be used with caution.

Morphometric analysis of mandibular ramus for sex determination on digital orthopantomogram

BACKGROUND

Identification of sex from skeletal remains is an important tool in forensic science. Mandibular ramus can be used for sex determination either on dry mandible or through orthopantomogram (OPG).

AIM

To determine the sex from mandibular ramus using digital OPG.

MATERIALS AND METHODS

The morphometric analysis was conducted on mandibular ramus of 1000 digital OPG using Kodak Master View version 4.3 software. Statistical analysis was performed, and independent t-test and discriminant function were applied.

RESULTS

The participants' age ranged from 21-60 years with an equal number of males and females. The mean dimensions of all parameters for ramus were higher in males and highly significant (P < 0.001). The total mean length of minimum and maximum ramus breadth was 27.44 ± 3.41 mm and 32.27 ± 3.40 mm, respectively. The maximum and projective ramus height was 71.78 ± 5.98 mm and 65.62 ± 6.19 mm, respectively. The coronoid height was 59.23 ± 6.08 mm. The correlation of gender with morphology of mandibular ramus was significant (P < 0.05). The overall accuracy for diagnosing sex was 69%, whereas for diagnosing male and female, the accuracy was 68% and 70%, respectively.

CONCLUSION

Measurements of mandibular ramus using OPG are helpful in sex determination.

Potential hominin affinities of Graecopithecus from the Late Miocene of Europe

The split of our own clade from the Panini is undocumented in the fossil record. To fill this gap we investigated the dentognathic morphology of Graecopithecus freybergi from Pyrgos Vassilissis (Greece) and cf. Graecopithecus sp. from Azmaka (Bulgaria), using new μCT and 3D reconstructions of the two known specimens. Pyrgos Vassilissis and Azmaka are currently dated to the early Messinian at 7.175 Ma and 7.24 Ma. Mainly based on its external preservation and the previously vague dating, Graecopithecus is often referred to as nomen dubium. The examination of its previously unknown dental root and pulp canal morphology confirms the taxonomic distinction from the significantly older northern Greek hominine Ouranopithecus. Furthermore, it shows features that point to a possible phylogenetic affinity with hominins. G. freybergi uniquely shares p4 partial root fusion and a possible canine root reduction with this tribe and therefore, provides intriguing evidence of what could be the oldest known hominin.

A secondary mandibular condylar articulation and collateral effects on a Late Neolithic mandible from Bois Madame rockshelter in Arbre, Belgium

A Neolithic Belgian mandible from Bois Madame rockshelter in Arbre presents an asymmetrical morphology resulting from a secondary, or false, articulation of the right mandibular condyle. The pathological articulation produced enlarged masseter, medial pterygoid and mylohyoid musculature on the right side as well as a flattening of the right incisal alveolus curvature. The secondary condylar articulation did not lead to pronounced asymmetry of attrition on the antimeres of the dental arcade. This is the most complete mandible from this Late Neolithic collective burial dating to the beginning of the Bronze Age circa 4000 years BP. It is possible that a fall or blow to the mental symphysis during early adolescence could have resulted in the partial intrusion of the mandibular condyle into the articulation disc of the temporomandibular joint capsule. When the affected condyle healed, a secondary, but serviceable articulation developed, producing unique stresses on the involved muscular tissue and ultimately resulted in an asymmetry of mandibular form.

Sex estimation using computed tomography of the mandible

Sex estimation of skeletal parts is of great value even in the DNA era. When computed tomography (CT) facilities were introduced to forensic institutes, new possibilities for sex estimation emerged. The aim of this study was to develop a CT-based method for sex estimation using the mandible. Twenty-five CT-based measurements of the mandible were developed and carried out on 3D reconstructions (volume rendering) and cross sections of the lower jaw of 438 adult individuals (214 males and 224 females). Intraobserver and interobserver variances of the measurements were examined using intraclass correlation coefficient (ICC) analysis. Five discriminant functions were developed using different states of completeness of the mandible. The success rates of these equations were cross validated twice. The measurements were found to be highly reliable (for intraobserver 0.838 < ICC < 0.995 and for interobserver 0.71 < ICC < 0.996). For a complete mandible, the correct classification rate was 90.8%. For incomplete mandibles, the correct classification rates varied from 72.9 to 85.6%. Cross-validation tests yielded similar success rates, for the complete mandible 89% and for the incomplete mandible 67.5 to 89%. We concluded that CT techniques are appropriate for estimating sex based on the mandible size and shape characteristics. Suggested discriminant functions for sex estimation are given with data on the correct classification rates.

Elliptical Fourier analysis: fundamentals, applications, and value for forensic anthropology

The numerical description of skeletal morphology enables forensic anthropologists to conduct objective, reproducible, and structured tests, with the added capability of verifying morphoscopic-based analyses. One technique that permits comprehensive quantification of outline shape is elliptical Fourier analysis. This curve fitting technique allows a form's outline to be approximated via the sum of multiple sine and cosine waves, permitting the profile perimeter of an object to be described in a dense (continuous) manner at a user-defined level of precision. A large amount of shape information (the entire perimeter) can thereby be collected in contrast to other methods relying on sparsely located landmarks where information falling in between the landmarks fails to be acquired. First published in 1982, elliptical Fourier analysis employment in forensic anthropology from 2000 onwards reflects a slow uptake despite large computing power that makes its calculations easy to conduct. Without hurdles arising from calculation speed or quantity, the slow uptake may partly reside with the underlying mathematics that on first glance is extensive and potentially intimidating. In this paper, we aim to bridge this gap by pictorially illustrating how elliptical Fourier harmonics work in a simple step-by-step visual fashion to facilitate universal understanding and as geared towards increased use in forensic anthropology. We additionally provide a short review of the method's utility for osteology, a summary of past uses in forensic anthropology, and software options for calculations that largely save the user the trouble of coding customized routines.

Assessment of sexual dimorphism using digital orthopantomographs in South Indians

INTRODUCTION

The identification of human skeletal remains plays a crucial role in forensic investigation and its accuracy depends on the available parts of the skeleton. The mandible is the hardest and strongest bone of the skull, which exhibits a high degree of sexual dimorphism and helps to identify the sex in human remains. The aim of this study was to develop discriminant function to determine sex from the mandibular radiographs in a South Indian (Visakhapatnam) population.

MATERIALS AND METHODS

This retrospective study consisted of 384 (192 males and 192 females) digital orthopantomographs (OPGs) divided into five groups according to age. Ten mandibular variables were measured using Planmeca Romexis software. The data were tabulated and subjected to discriminant function analyses using Statistical Package for the Social Sciences (SPSS) software (version 20.0) package.

RESULTS

All the parameters showed a significant sexual dimorphism (P < 0.001) except for the gonial angle. An overall accuracy of 75.8% was achieved and coronoid height (CrH) was the single best parameter providing an accuracy of 74.1%.

CONCLUSION

All the mandibular variables except for the gonial angle (GA) were found to be reliable in determining the sex in South Indians for forensic purposes.

Gender determination by radiographic analysis of mental foramen in the Maharashtra population of India

Context:

Identification of gender is of primary importance in forensic investigations when only fragment of skull remains. Mandible is a hard bone and exhibits a high degree of sexual dimorphism. Gender differences were observed in the height of mandible, gonial angle, bigonial breadth, bicondylar breadth, and position of mental foramen (MF).

Aims of the Study:

The purpose of this study is to evaluate gender differences in distances from superior border of MF (SMF) and inferior border of MF (IMF) to the lower border of mandible (LBM) and height of mandible in the Maharashtra population.

Materials and Methods:

A total of 400 patients (200 males and 200 females) were considered for the study. The panoramic radiographs of patients were captured using Xtropan 2000 system and Carestream (T-Mat GIRA) films. The distance from SMF and IMF to the LBM and the height of mandible was measured.

Statistical Analysis Used:

Unpaired t-test was applied to calculate the differences between the genders.

Results:

The distance from SMF and IMF to LBM and height of mandible was more in males when compared to females, which was statistically significant.

Conclusion:

The distances from SMF and IMF to the LBM and height of the mandible showed sexual dimorphism in the Maharashtra population of India.

Accuracy of mandibular measurements of sexual dimorphism using stabilizer equipment

The objective of this investigation was to compare the accuracy of mandibular measurements using a stabilizer (MS) with gold standard computed tomography (GS) images. Sixty mandibles were studied. Werth TomoScope HV Compact® was used to obtain CT images (GS), and the MS was also used. Analysis of the CT scans was performed using the VG Studio Max software® (Volume Graphics GmbH, Heidelberg, Germany), and MS was used after the proper positioning of the mandible. Descriptive and paired t test measures were used, and a ROC curve was calculated, as well as sensibility and specificity. MedCalc and STATA 13.0® were used (95% level of significance). Bicondylar breadth, bicoronoid breadth and minimum ramus breadth reached the highest concordance correlation coefficients at 0.99 (0.99-1.00), 0.99 (0.99-1.00) and 1.00 (0.99-1.00), respectively. Comparing observers with GS, the lowest accuracy was noted for the maximum mandibular length [0.59 (0.45-0.69), 0.64 (0.51-0.74)], the breadth of the right (0.14 (0.04-0.23), 0.14 (0.004-0.24)) and left mandibular body [0.14 (0.03-0.24), 0.16 (0.05-0.26)], and the right [0.58 (0.45-0.69), 0.63 (0.51-0.73) and left (0.59 (0.45-0.70), 0.59 (0.46-0.69)] mandibular angle. Various measurements exhibited good sensibility for males using MS: maximum mandibular length (78.12), bicondylar breadth (78.12), left mandibular notch breadth (84.37), and the left height of the mandibular body at the mental foramen (75.00). High specificity in discriminating females was observed for the left maximal ramus height (85.19), mandibular length (85.71), bicoronoid breadth (96.43), right height of the mandibular body at the mental foramen (82.19), bimental breadth (78.57), breadth right (92.86) and left (96.43) mandibular body, minimum ramus breadth (89.29), and left mandibular angle (85.71). MS was able to discriminate sexual dimorphism.

Evaluation of mandibular volume classified by vertical skeletal dimensions with cone-beam computed tomography

OBJECTIVE

 To investigate the relationship between anteroposterior and vertical differences in maxillofacial morphology and mandibular volume.

MATERIALS AND METHODS

 Subjects comprised 213 Japanese adults (84 males and 129 females) who were divided into three groups based on mandibular basal arch (ANB) and Wits, measured in a cephalometric analysis: Class I (-1° ≤ ANB < 4°,-1 mm ≤ Wits < 0 mm), Class II (ANB ≥ 4°, Wits ≥ 0), and Class III (ANB <-1°, Wits <-1 mm). Subjects were also divided into three groups based on the mandibular plane angle (Mp), as follows: hypodivergent (Mp < 23°), normodivergent (Mp  =  23-30°), and hyperdivergent (Mp > 30°) groups. Mandibular volume was measured from cone-beam computed tomographic images that were analyzed using Analyze™ image processing software and compared among the three groups in each classification.

RESULTS

 No significant differences were noted in mandibular volume among Classes I, II, and III. An inverse relationship was found between mandibular volume and Mp, and a significant difference was noted in mandibular volume between the hypodivergent and hyperdivergent groups.

CONCLUSIONS

 In addition to two-dimensional analysis, such as lateral cephalometry, three-dimensional information such as volume, provided by cone-beam computed tomography, contributes to a more detailed assessment of maxillofacial morphology.

The Biological Profile of Unidentified Human Remains in a Forensic Context

Estimation of the biological profile of unidentified human remains is a critical component of an anthropologic evaluation of unidentified human remains. The profile is used to search for missing persons that may match the decedent. The individual components of sex, ancestry, stature, and age at death require reliable methods to ensure accurate recording of these biological markers. This article showcases an unidentified skeleton that was misclassified as a female when the original evaluation was done in 1963. The revaluation in 2004 quickly led to resolution of the identity. Methods used today to evaluate the components of the biological profile are reviewed along with a limited review of the historic literature.

Determination of sexual dimorphism in humans by measurements of mandible on digital panoramic radiograph

Background:

Identification of sex is the first step in forensic science obtained from skeletal remains. Mandible, being a strong bone that is difficult to damage and disintegrate, is an important tool in sex determination. The present study is aimed to assess, compare, and evaluate the mandibular measurements as seen on digital panoramic radiographs to analyze their use in sexual dimorphism assessment.

Materials and Methods:

This retrospective study was conducted using digital panoramic images of 100 each in both genders. Mandibular measurements were carried out utilizing RadiAnt DICOM Viewer 2.2.9 (32 bit) software (Medixant Company, Poland) and subjected to statistical analysis.

Results:

Descriptive statistics for all the parameters on the right and left sides of mandible in both males and females were analyzed. Inferential statistics were performed using t-test to compare males and females with different variables. A statistical significance of P < 0.001 has been demonstrated for all the variables (except linear measurement of mandibular foramen). All variables showed increased measurements in males than in females. The accuracy of sex determination in mandibular ramus measurements is 79.5% on right side and 77% on left side, where as, in linear mandibular measurements it is 76% on right side and 79.5% on left side.

Conclusion:

Mandibular measurements on digital radiograph are useful in sex determination, and this study can be compared with other similar studies.

Craniometric study for sex determination in a Thai population

Sex determination is an important step in biological identification from skeletal remains, especially in forensic circumstances. Many authors suggested that the morphological study was more subjective than the metric. There are various craniometric studies in different populations. They revealed that there was population-specific for the sex discriminant equation derived from each population. Thus, the present study aimed to evaluate sexual dimorphism and develop the discriminant function from 200 Thai skulls. Twenty-five standard cranial measurements were examined. The results revealed that males' cranium were statistically significant larger than females' in all measurements (P<0.05), except for minimum breadth of nasal bone. Sexual dimorphism index also expressed relatively high male/female ratio indicating great sexual dimorphism. The best practical equation for sex determination with six measurements (maximum cranial length, bizygomatic breadth, biauricular breadth, nasal height, biorbital breadth and right mastoid length) was derived from a stepwise discriminant method. This equation with 90.6% accuracy (91.1% in male and 90.0% in female) can provide valuable application utilizing in sex determination from skull in a Thai population.

Sexual dimorphism of the mandible in a contemporary Chinese Han population

A present limitation of forensic anthropology practice in China is the lack of population-specific criteria on contemporary human skeletons. In this study, a sample of 203 maxillofacial Cone beam computed tomography (CBCT) images, including 96 male and 107 female cases (20-65 years old), was analyzed to explore mandible sexual dimorphism in a population of contemporary adult Han Chinese to investigate the potential use of the mandible as sex indicator. A three-dimensional image from mandible CBCT scans was reconstructed using the SimPlant Pro 11.40 software. Nine linear and two angular parameters were measured. Discriminant function analysis (DFA) and logistic regression analysis (LRA) were used to develop the mathematics models for sex determination. All of the linear measurements studied and one angular measurement were found to be sexually dimorphic, with the maximum mandibular length and bi-condylar breadth being the most dimorphic by univariate DFA and LRA respectively. The cross-validated sex allocation accuracies on multivariate were ranged from 84.2% (direct DFA), 83.5% (direct LRA), 83.3% (stepwise DFA) to 80.5% (stepwise LRA). In general, multivariate DFA yielded a higher accuracy and LRA obtained a lower sex bias, and therefore both DFA and LRA had their own advantages for sex determination by the mandible in this sample. These results suggest that the mandible expresses sexual dimorphism in the contemporary adult Han Chinese population, indicating an excellent sexual discriminatory ability. Cone beam computed tomography scanning can be used as alternative source for contemporary osteometric techniques.

Sexual dimorphism and population variation in the adult mandible : Forensic applications of geometric morphometrics

This article forms part of an ongoing series of investigations designed to apply three-dimensional (3D) technology to problems in forensic anthropology. We report here on new morphometric data examining sexual dimorphism and population variation in the adult human mandible. The material is sourced from dissection hall subjects of South African and American origin consequently the sex and a statement of age are known for each individual. Thirty-eight bilateral 3D landmarks were designed and acquired using a Microscribe G2X portable digitizer. The shape analysis software morphologika (www.york.ac.uk/res/fme) is used to analyze the 3D coordinates of the landmarks. A selection of multivariate statistics is applied to visualize the pattern, and assess the significance of, shape variation between the sexes and populations. The determination of sex and identification of population affinity are two important aspects of forensic investigation. Our results indicate that the adult mandible can be used to identify both sex and population affinity with increased sensitivity and objectivity compared to standard analytical techniques.

Assessment of Volume and Height of the Coronoid Process in Patients With Different Facial Types and Skeletal Classes: A Cone-Beam Computed Tomography Study

PURPOSE

To determine the height and volume of the mandibular coronoid process (CP) by cone-beam computed tomography (CBCT) and to identify the presence of any correlations of these measurements with age, gender, facial type, and skeletal class.

MATERIALS AND METHODS

The sample consisted of 132 patients from a departmental routine patient base. After CBCT, CP height was determined using OnDemand 3D software (CyberMed, Seoul, Republic of Korea), and CP volume was obtained using ITK-SNAP 3.0 software (Cognitica, Philadelphia, PA). Measurements were subjected to analysis of covariance against facial type, skeletal class, gender, and age, with a significance level of 5%.

RESULTS

CP height and volume were similar regardless of age, facial type, and skeletal class. However, the 2 measurements were statistically different regarding gender, with larger values for men than for women.

CONCLUSIONS

These observations suggest that gender is the only factor influencing the height and volume of the CP.

Determination of sex by discriminant function analysis of mandibles from a Central Indian population

Context:

Identification of sex from skeletal remains is one of the important forensic considerations. Discriminant function analysis is increasingly used to determine the sex from skeleton.

Aims:

To develop discriminant function to determine sex from mandible in a Central Indian population.

Settings and Design:

This was a prospective study done at the Department of Anatomy.

Materials and Methods:

The mandibles used in the present study were from the museum specimens. Only 82 adult mandibles (55 male and 27 female) that had been preserved were selected. Ten mandibular parameters were measured.

Statistical Analysis Used:

Statistical analysis was conducted using Statistical Package for Social Sciences (SPSS) for Windows, version 16. The level of statistical significance was set at P < 0.05.

Results:

Using stepwise discriminant function analysis, only six variables were selected as the best discriminant between sexes, with the projection length of corpus mandibulae being the most dimorphic. It was observed that sex classification accuracy of the discriminant functions ranged from 57.3 to 80.5% for the individual variables, 81.7% for the stepwise method, and 85.4% for the direct method.

Conclusion:

The results of the study show that mandibles can be used for determining sex and the results are comparable with other similar studies. The studied mandibular variables showed sexual dimorphism with an accuracy comparable with other skeletal remains, next to cranium and pelvis.

Postmortem CT morphometry with a proposal of novel parameters for sex discrimination of the mandible using Japanese adult data

Major human sex differences in the mandible after adolescence include the overall size as well as the shape of the chin and mandibular angle; however, objective interpretation of discrimination accuracy is difficult for these morphological indicators. The present study investigated measurements of the mandible for sex discrimination using postmortem CT morphometry in forensic autopsy cases of Japanese subjects after adolescence (age>16 years; male, n=116, and female, n=106), including the proposal of novel parameters representing the overall mandibular size and shape. The distance between the gnathion and condylus (gn-cdl), and bigonial width (go-go), as well as the angle formed by bilateral gn-cdl lines (Agn-cdl), correlated with bicondylar breadth (cdl-cdl), independent of the body height, showing no significant sex difference. The distance from the gn to the cdl-cdl line (oblique length), the ratio of Agn-cdl to cdl-cdl, and the oblique triangular area formed by bilateral gn-cdl and cdl-cdl lines (Δobl), which were proposed as indicators of chin protrusion, showed significant sex differences (p<0.001). Overall sensitivity and specificity at respective discriminating points for sex estimation were 0.72 and 0.78 at 105.0mm for the oblique length, 0.73 and 0.83 at 0.49 for the Agn-cdl to cdl-cdl ratio, and 0.82 and 0.78 at 643 mm(2) for Δobl; the efficacy for females was greater in younger subjects. Although these parameters weakly depended on the body height (p<0.0001), the correlations were insufficient for stature estimation. These findings suggest the efficacy of CT morphometry of the mandible for sex discrimination with quantitative assessment.

Description of sex difference as prescription for sex change: on the origins of facial feminization surgery

This article explores the research project that led to the development of facial feminization surgery, a set of bone and soft tissue reconstructive surgical procedures intended to feminize the faces of male-to-female trans- women. Conducted by a pioneering surgeon in the mid-1980s, this research consisted of three steps: (1) assessments of sexual differences of the skull taken from early 20th-century physical anthropology, (2) the application of statistical analyses taken from late 20th-century orthodontic research, and (3) the vetting of this new morphological and metric knowledge in a dry skull collection. When the 'feminine type' of early 20th-century physical anthropology was made to articulate with the 'female mean' of 1970s' statistical analysis, these two very different epistemological artifacts worked together to produce something new: a singular model of a distinctively female skull. In this article, I show how the development of facial feminization surgery worked across epistemic styles, transforming historically racialized and gendered descriptions of sex difference into contemporary surgical prescriptions for sex change. Fundamental to this transformation was an explicit invocation of the scientific origins of facial sexual dimorphism, a claim that frames surgical sex change of the face as not only possible, but objectively certain.

Radiomorphometric analysis of frontal sinus for sex determination

Context:

Sex determination of unknown individuals carries crucial significance in forensic research, in cases where fragments of skull persist with no likelihood of identification based on dental arch. In these instances sex determination becomes important to rule out certain number of possibilities instantly and helps in establishing a biological profile of human remains.

Aims:

The aim of the study is to evaluate a mathematical method based on logistic regression analysis capable of ascertaining the sex of individuals in the South Indian population.

Settings and Design:

The study was conducted in the department of Oral Medicine and Radiology.

Methods and Material:

The right and left areas, maximum height, width of frontal sinus were determined in 100 Caldwell views of 50 women and 50 men aged 20 years and above, with the help of Vernier callipers and a square grid with 1 square measuring 1mm² in area.

Statistical analysis used:

Student's t-test, logistic regression analysis.

Results:

The mean values of variables were greater in men, based on Student's t-test at 5% level of significance. The mathematical model based on logistic regression analysis gave percentage agreement of total area to correctly predict the female gender as 55.2%, of right area as 60.9% and of left area as 55.2%.

Conclusion:

The areas of the frontal sinus and the logistic regression proved to be unreliable in sex determination. (Logit = 0.924 - 0.00217 × right area).

Sex determination of human mandible using metrical parameters

INTRODUCTION

Determination of sex from an unknown human bone is an important role in forensic and anthropology field. The mandible is the largest and hardest facial bone, that commonly resist post mortem damage and forms an important source of information about sexual dimorphism.

AIM

To determine the sex of unknown human adult mandible using metrical parameters.

MATERIAL AND METHODS

A random collection of 250 dry, complete, undamaged human adult mandibles of South Indian population were subjected to metrical parameters like Bigonial breadth, Bicondylar breadth and Mandibular length using Mandibulometer and Vernier caliper.

STATISTICAL ANALYSIS USED

The data's were expressed as Mean ± SD and then analyzed by t-test by using SPSS software. Discriminating point and limiting points were also calculated.

RESULTS

The mandibular length, bigonial breadth and bicondylar breadth showed significant statistical gender difference.

CONCLUSION

The present study revealed that the sex of human mandible can be assessed by using metrical parameters as an additional tool to establish the identity of a person.

Mandibular ramus: An indicator for sex determination - A digital radiographic study

Background:

The identification of skeletal remains is of paramount importance in medico-legal investigations. The skeletal components most often investigated for gender determination are the pelvis and skull, with the mandible being a practical element to analyze sexual dimorphism in the fragmented bones. Presence of a dense layer of compact bone makes it very durable and well preserved than many other bones. Mandibular ramus can be used to differentiate between sexes and it also expresses strong univariate sexual dimorphism. When skeleton sex determination is considered, metric analyses on the radiographs are often found to be of superior value owing to their objectivity, accuracy, and reproducibility.

Aims and Objectives:

(1) To measure, compare, and evaluate the various measurements of mandibular ramus as observed on orthopantomographs. (2) To assess the usefulness of mandibular ramus as an aid in sex determination.

Materials and Methods:

A retrospective study was conducted using orthopantomographs of 50 males and 50 females, which were taken using Kodak 8000C Digital Panoramic and Cephalometric System (73 kVp, 12 mA, 13.9 s). Mandibular ramus measurements were carried out using Master View 3.0 software. The measurements of the mandibular ramus were subjected to discriminant function analysis.

Results:

We observed each variable of the mandibular ramus to be a significant predictor in classifying a given sample (P < 0.001).

Conclusion:

This study on mandibular ramus measurements using orthopantomograph shows strong evidence suggesting that the ramus can be used for gender determination for forensic analysis.