Measurements of the Foramen Magnum and Mandible in Relation to Sex Using CBCT

A, Natarajan S. Evaluation of Foramen Magnum for Sex Determination among the Population of Dakshina Kannada District: A Retrospective CBCT Study

Background

This study aims to evaluate the accuracy rate of foramen magnum dimensions in determining sex among the South Indian population using discriminant functional analysis.

Methods

An observational study in which CBCT images from 200 full field of view (FOV) scans were analysed. The dimensions of the foramen magnum were measured. Intra- and interobserver reliability were calculated. Independent t-tests were used to compare the various parameters between sexes. Stepwise discriminant function analysis was used to determine sex.

Results

A total of 200 CBCT scans were included in the study. The mean age (±SD) was 25.66 (±7.11) years among males and 24.64 (±5.12) years among females. The measurements and the circumference of the foramen magnum were significantly (p < 0.001) greater in males than in females. The univariate analysis of foramen magnum measurements reached an accuracy rate of 73.5% in sex determination. The discriminant function analysis combining the foramen magnum measurements and circumference yielded an overall predictability rate of 66.5% for determining sex.

Conclusion

Taking into account the predictability rate of sex based on foramen measurement in the present population, it can be concluded that its applicability should be limited to cases associated with fragmentary skull bases.

Biological profiling using the human mandible

BACKGROUND

In the absence of soft tissue, skeletal remains are analyzed to identify the deceased. This assessment involves establishing the biological profile that aids medicolegal investigations and fulfils the right of the dead to be identified. Since the mandible is the strongest bone in the skull and easily identifiable, even when fragmented, this study aimed to systematically review its value in constructing the biological profile in the published literature. We searched PubMed, ScienceDirect, Scopus, and Latin American and Caribbean Health Sciences Literature and collected cross-sectional studies published in English before 2021. A risk of bias assessment was completed based on Joanna Briggs Institute's critical appraisal tools. The data are presented descriptively and were analyzed using Microsoft Office Excel 365.

HIGHLIGHT

Of the 104 eligible articles, 94 examined the sexual dimorphism of the mandible, while 25 attempted to estimate age. Ancestry and stature were the least explored biological characteristics (five and one articles, respectively). A metric analysis was the most common approach (n = 80), followed by morphological analysis and combined morphologic and metric techniques (n = 18 and n = 6, respectively). The results showed no statistically significant correlation between an individual's mandible and stature. Orthopantomogram radiography continues to be the most common radiographic technique for assessing the mandible.

CONCLUSION

The mandible is reliable when used for sex estimation; however, caution should be exercised in relying solely on it for morphological assessments. This review provides guidance on estimating age, sex, and ancestry directly from mandibular specimens or radiographs.

Morphometric analysis of the foramen magnum in sex estimation: An additional 3DCT study from Nepal on a larger sample

Background

Estimation of sex of the skeletal remains plays a vital part in the identification of an individual. This study is focused on the morphometric measurements of the foramen magnum region and examining the accuracy of sexual dimorphism in the Nepalese population.

Methods

Measurements were obtained from 3D computed tomography (CT) scan of 261 Nepalese adult cranial bases with known age and sex. Length and breadth of the foramen magnum, length and breadth of right and left occipital condyles and maximum and minimum intercondylar distance were measured on the base of the skull CT images.

Results

The mean values for all parameters were higher in males than females except for the maximum intercondylar distance. Sex prediction done with discriminant function analysis could classify the skull with an overall accuracy of 70.5%-71%.

Conclusions

It can be concluded from the results that the morphometric study of the foramen magnum is less reliable for sex estimation in the Nepalese population.

Anatomical Evaluation of the Foramen Magnum on Cone-Beam Computed Tomography Images and Review of Literature

Background and objective The morphology and morphometry of the foramen magnum (FM), which provides a passageway to vital neurological structures that relay information to and from the brain and spinal cord, are significant for many surgical approaches and applications. It was aimed to investigate the morphometric and morphological features of the FM on the cone-beam computed tomography (CBCT) images and to review the literature in detail. Methods CBCT images of 400 individuals (200 males, 200 females, aged between 18 and 65) were evaluated by Planmeca Romexis Viewer. The length, width, perimeter, and area of the FM were examined and samples were classified according to shape. Also, the FM index (FMI) was calculated. Results The mean values of the length, width, and perimeter were found to be 36.75±2.50 mm, 32.55±2.93 mm, and 108.35±7.50 mm, respectively. The area of FM was found to be 941.81±128.26 mm², 946.83±127.39 mm², and 895.76±123.50 mm² with Planmeca Romexis Viewer, Radinsky formula, and Teixeira formula, respectively. All parameters were significantly larger in males than females. There was no correlation between age and these parameters. Also, seven shapes were determined for FM, and the most common shape was oval. FM index was evaluated according to the Martin and Saller classification. It was found that 16.5% of the cases belonged to the narrow, 16% belonged to the medium, and 67.5% to the large FM index. There was no correlation between age and FM index. Conclusion Morphometric and morphological features of the FM located in the craniovertebral junction (CVJ), which is a highly complex area, are variable. Surgical procedures and approaches in this region are essential due to the high mortality rate. For this reason, anatomical structures in these regions should be well known before surgery. The quantitative data presented in this study, which made a detailed literature comparison, may assist in surgical procedures around the FM and the planning of these procedures.

Estimation of Sexual Dimorphism of the Mandible in Coastal Karnataka and Kerala Populations using Cone Beam Computed Tomography

Objective The mandible has been used for sex determination and forensic identification due to its unique anatomy and morphology. Every part of the mandible is unique, including the shape and size of the temperomandibular joint, the ramus, the body and the symphysis region, and the inferior alveolar canal. In addition, the position and placement of the teeth within their sockets are unique for every individual.

Sample Population A study was conducted on 20 males and females to estimate sexual dimorphism using anthropometric measurements obtained by cone beam computed tomography images of the mandible of Karnataka and Kerala populations.

Materials and Methods The mean, standard deviation, and standard error along with the confidence interval of different measurements were documented. Various measurements between the sexes were compared using Student's t-test. Association between categorical variables was analyzed using the Chi-square test. A p-value < 0.05 was considered to be statistically significant. Data were analyzed using statistical SPSS software.

Results The p-value of mRBr L, GA L, and GA R among females was significantly higher in the Karnataka population when compared with that in the Kerala population. The Karnataka State population showed significantly higher values of RL R, BiGBr, and BiCBr among males, and the p-value of the Kerala population for GGL L and GGL R was significant and higher among the males.

Conclusion The data derived from the above study suggest that the mandibular anthropometric measurements used may be applied for forensic sex estimation.

Sex estimation from foramen magnum parameters in adult Turkish population: A computed tomography study

Identification of skeletal relics is crucial for medicolegal purposes. Sex estimation is one of the critical parts providing the identification of skeletal relics. In forensic practice, sex estimation requires multidisciplinary studies of such as forensic medicine, anatomy, dentistry and radiology. Recently, radiological studies on this subject have been increasing with the developing technology. The objective of this study is to examine the usage of radiological dimensions of foramen magnum for sex estimation in human skulls by developing discriminant functions in Turkish population. We analyzed 600 (300 males and 300 females) Computerized Tomography (CT) images of Turkish individuals aged between 21 and 50. Four measurements were obtained from CT images. All measurements in males were significantly greater than in females, and they provided the higher sex classification accuracy. The area of the foramen magnum calculated by Radinsky's formula was the best measurement for sex estimation with a 75% accuracy rate. In conclusion, the CT images of foramen magnum show sexual dimorphism in our population. To use population specific data would be the most appropriate approach for sex estimation.

A Novel Extended Deep Plane Facelift Technique for Jawline Rejuvenation and Volumization

BACKGROUND

Jawline aging is a complex process. We believe loss of posterior jawline definition and volume depletion is an underappreciated factor in the aging face.

OBJECTIVES

The aim of this study was to describe a novel composite, rotational flap modification of an extended deep-plane rhytidectomy. We evaluated long-term efficacy on improving jawline contour and volumization of the posterior mandibular region overlying the gonial angle.

METHODS

We performed a prospective study on patients who underwent our modification of extended deep-plane rhytidectomy. We define and introduce the mandibular defining line, a new anatomic metric in evaluating the mandibular contour. We define the area of the posterior lower face overlying the gonion and mandibular angle as the gonial area. Using 3-dimensional photography, we quantify contour changes along the mandibular border and volume change along the gonial area.

RESULTS

Eighty-nine patients (178 hemifaces) were analyzed. The mean gonial area volume gained was 3.5 cc. Average follow-up was 19 months. There was a statistically significant change in the mean mandibular defining line from 7.1 cm preoperatively to 9.8 cm postoperatively. This represents a lengthening of the visual perspective of the mandibular contour of 2.7 cm.

CONCLUSIONS

Composite, rotational flap modification of extended deep-plane rhytidectomy provides significant long-term augmentation of volume to the posterior mandibular region and lengthens the visual perspective of the inferior mandibular contour, creating a more youthful jawline. In selected cases, this may obviate the need for other volumization procedures used to improve jawline contour, such as autologous fat grafting.

LEVEL OF EVIDENCE: 4

Sex estimation using paranasal sinus discriminant analysis: a new approach via cone beam computerized tomography volume analysis

Sex estimation is an important step for subject identification in forensic medicine, to which paranasal sinuses may contribute, as they remain intact even upon severe damage to the skull and other bones. Cone beam computerized tomography (CBCT) is an excellent tool in the examination of these structures. The present study aimed to evaluate the maxillary, frontal and sphenoidal sinuses through a discriminant analysis to determine the sex correlations with foramen magnum measurements were also assessed. Two-hundred cranial CBCT scans were analysed. The volume of the maxillary, frontal and sphenoidal sinuses were measured using the ITK-SNAP software (4.0.2). Student's t test and the Mann-Whitney test were applied for the descriptive analysis of independent samples, and data were subjected to discriminant analysis. The volumes of the maxillary, frontal and sphenoidal sinuses of female subjects were smaller than those of male subjects (p < 0.001). Upon summing up the volumes of the evaluated paranasal sinuses, the chances to correctly determine an individual's gender are 96.2% and 92.7% for males and females, respectively. When correlating said values with foramen magnum measurements, sex identification chances increase to 100%. Thus, adult paranasal sinus volumes analysed by CBCT may be useful for sex identification when summed together and correlated with foramen magnum measurements.

Sexing the Cranium from the Foramen Magnum Using Discriminant Analysis in a Brazilian Sample

In the identification process, the foramen magnum has shown controversial results in sex estimation. The present study aimed to analyze the morphometric variables of the foramen magnum in Brazilian adult cranium for sex estimation. The sample was composed of 100 craniums (53 males and 47 females) from the documented collection of the Institute of Teaching and Research in Forensic Sciences. The protocol measurement was constituted of two linear measurements: maximum length of the foramen magnum and maximum breadth of the foramen magnum and two formulas to calculate the area, method one (M1) and method two (M2). Descriptive statistics showed statistically significant differences between sex (p<0.05) for all variables. The univariate discriminant functions showed an accuracy between 56.0-62.0%, and the multivariate analysis showed a percentage of accuracy between 60.0-65.0%, the greatest accuracy was found combining the two linear measurements with M1(71.7%), even after cross-validation (66%). Receiver Operating Characteristic (ROC) curve analysis showed that M2 is the best parameter for estimating sex (AUC=0.693). A reference table for Brazilians using the foramen magnum parameters was developed based on the results of the ROC curve analysis. In conclusion, the foramen magnum should be used with caution to estimate sex in forensic cases of fragmentary craniums, due to the limited accuracy.

Sex determination of Han adults in Northeast China using cone beam computer tomography

The purpose of this study was to obtain the morphological data of the maxillofacial region of Han nationality adults in Northeast China, and to explore the methods and appropriate variables of three-dimensional reconstruction technology for sex determination using Cone beam computer tomography (CBCT). The CBCT images of 420 adults (210 males, 210 females) aged 18-70years were reconstructed by MIMICS 17.0 software and sixteen observation indexes were measured and analyzed statistically. The results demonstrated that twelve of sixteen variables expressed significant sexual difference (p<0.01) which were as follows: mandibular angle (X₁),area of mandibular foramen (X₂), bi-gonial breadth (X₃), koronoidbreite (X₄), Height of symphysis (X₅), Min-height of mandibular notch (X₆), Min-breadth of mandibular ramus (X₇), Buccal side bone thickness of MF (X₈), Horizontal diameter of MF (X₁₁), Vertical from prosthion to palatal breadth (X₁₂), palatal breadth (X₁₃), The ratio of HD-MF and VD-MF (X₁₅). Then the sexual discriminant equation which was suitable for people at the age of 18-70 was established using stepwise method: Y=-0.059X₁+0.313X₂+0.1X₃+0.061X₄+0.044X₅+0.041X₆+0.076X₁₃-17.215. It was found that the cross-validated grouped overall predictive accuracy was 87.4%. It could correctly identify males in 85.7% and females in 89% of the cases. This study has accumulated morphological data of maxillofacial skeleton from adults of Han nationality in Northeast China, which provided guiding significance for sex determination and clinical application in forensic science, archaeology, criminal investigation, iconography and clinical three-dimensional (3D) print. Evaluation variables and related discriminant functions of sex determination using CBCT for three-dimensional reconstruction technology provided a new theoretical basis and practical means for sex determination.

Sex estimation with the total area of the proximal femur: A densitometric approach

The estimation of sex is a central step to establish the biological profile of an anonymous skeletal individual. Imaging techniques, including bone densitometry, have been used to evaluate sex in remains incompletely skeletonized. In this paper, we present a technique for sex estimation using the total area (TA) of the proximal femur, a two-dimensional areal measurement determined through densitometry. TA was acquired from a training sample (112 females; 112 males) from the Coimbra Identified Skeletal Collection (University of Coimbra, Portugal). Logistic regression (LR), linear discriminant analysis (LDA), reduce error pruning trees (REPTree), and classification and regression trees (CART) were employed in order to obtain models that could predict sex in unidentified skeletal remains. Under cross-validation, the proposed models correctly estimated sex in 90.2-92.0% of cases (bias ranging from 1.8% to 4.5%). The models were evaluated in an independent test sample (30 females; 30 males) from the 21st Century Identified Skeletal Collection (University of Coimbra, Portugal), with a sex allocation accuracy ranging from 90.0% to 91.7% (bias from 3.3% to 10.0%). Overall, data mining classifiers, especially the REPTree, performed better than the traditional classifiers (LR and LDA), maximizing overall accuracy and minimizing bias. This study emphasizes the significant value of bone densitometry to estimate sex in cadaveric remains in diverse states of preservation and completeness, even human remains with soft tissues.

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.