Sexual dimorphism in the growth of the cranium

Sex determination by Ct -scan analysis of the mastoid bone: A cross-sectional study

The mastoid bone, situated at the base of the skull and characterized by its compact structure in the petrous portion, being among the slowest-growing bones, has gained recognition as a valuable anthropological tool for sex determination. Thus, we have proposed to assess the reliability of the mastoid process in sex determination in a Tunisian population using CT-scan analysis. A cross-sectional study was conducted. CT scans forming the mastoid triangle were analyzed using a General Electric Bright Speed scanner. Nine measurements were taken by a single observer, ensuring reliability through intra- and inter-observer assessments. Normalization and statistical analyses, including logistic regression, were applied to identify sex-discriminating variables. The model's performance was evaluated using learning curves, cross-validation, and various metrics. The resulting logistic regression equation, coefficients, and intercept provided a predictive tool for sex determination. A total of 256 cranial CT scans (126 males, 130 females) were analyzed. Our study revealed that the mastoid region approach achieved an overall accuracy of 80.8 % in sex identification within the examined population. The method demonstrated a sensitivity of 78.9 % and specificity of 81.8 %. All investigated variables (AP, PM, AM, CMH, TMH, OSDmax, OCDmax, MA) exhibited discriminatory capabilities for sex determination, except for AIA. Notably, the most effective discriminators were AP, CMH, and OSDmax. Utilizing an ROC curve analysis to optimize mastoid variables for maximum sensitivity and specificity, we obtained excellent results, with an area under the curve reaching 91 %.

Orbital shape in sheep and goats with sex and breed factors

The purpose of this study was to identify the dimorphic structures of the orbita based on breed and sex factors through shape analysis across species. Additionally, the study aimed to ascertain the variability between the two species. A total of 86 (51 sheep-Akkaraman [Ak] and Morkaraman [Mk], 35 goats-Hair [Hr] and Honamlı [Hm]) skulls were used in the study. It was decided to designate 36 landmarks to represent the orbit's edge. In the principal component analysis, 68 PCs were calculated. It was determined that PC1, PC2 and PC3 explained the total variance in morphology by 26.909%, 16.147% and 13.616%, respectively. According to the cross-validation results, the goats were grouped with 95% (Hm: 100%, Hr: 90%), while the sheep were grouped with 56% (Ak: 50%, Mk: 63%). Therefore, dimorphism among goat breeds on orbita shape was more pronounced compared to sheep. In the discriminant function analysis of the sex groups, Procrustes and Mahalanobis distance values in goats were 0.04425425 (p < 0.0001) and 5.3733 (p = 0.9550), in sheep 0.03513424 (p < 0.0001) and 7.1003 (p = 0.9414), respectively, was detected. According to the cross-validation results, in terms of sex, goats were correctly grouped at a rate of 74% (F: 73%; M: 75%) and sheep breeds were correctly grouped at a rate of 72% (F: 77%; M: 66%). Factors such as habitat selection, breeding behaviours and ecological environment may show anatomical differences within breeds as well as between breeds. Therefore, various measurement techniques are used to reveal these differences. As a result, it is thought that the study will contribute to many disciplines, especially taxonomy and zooarchaeology, by analysing the shape of the orbita of sheep and goat breeds, the domestication of which dates back to ancient times, and revealing the similarities and differences between species and according to sex.

Characterization of cranial growth patterns using craniometric parameters and best-fit logarithmic growth curves

Few studies have reported a complete quantitative database of cranial growth, from infancy to adulthood, as a reference through three-dimensional analysis. Our study aimed to characterize cranial growth patterns using craniometric parameters by establishing sex- and age-specific norms. In total, 1009 Korean patients (male-to-female ratio, 2:1; age range, 0-18 years) who underwent thin-slice computed tomography (CT) scans for head trauma were divided into 20 age groups, with a 6-month interval for those under 2 years and a 1-year interval for those over 2 years. After four reference planes [Frankfurt horizontal (FH), midsagittal, and two coronal planes passing the sella (S) and basion (B)] had been established, intracranial volume (ICV), anteroposterior diameter (APD), biparietal diameter (BPD), cranial heights (CHs), cephalic index (CI, BPD/APD), and height index (HI, CH-B/APD) were measured using Mimics software. Best-fit logarithmic curves were derived using a linear regression model. The best-fit curves for ICV (cm3) were y = 785.6 + 157*ln(age) for males (R2 = 0.5752) and y = 702 + 150.5*ln(age) for females (R2 = 0.6517). After adjustment for age, males had higher values of ICV, APD, BPD, and CHs than females (all p < 0.0001). ICV, APD, BPD, and CHs demonstrated a rapid increase during the first few months of life, reaching 90-95% of the adult size by 5-6 years of age, while CI and HI showed a continuous decline by 4%, regardless of sex. This study presented cranial growth references for more than 1000 of the Korean population aged up to 18 years. This might help to provide guidelines for diagnosis and treatment (including timing, amount, and direction) for cranial reconstruction in pediatric patients with craniosynostosis.

Forensic Gender Determination by Using Mandibular Morphometric Indices an Iranian Population: A Panoramic Radiographic Cross-Sectional Study

Gender determination is the first step in forensic identification, followed by age and height determination, which are both affected by gender. This study assessed the accuracy of gender estimation using mandibular morphometric indices on panoramic radiographs of an Iranian population. This retrospective study evaluated 290 panoramic radiographs (145 males and 145 females). The maximum and minimum ramus width, coronoid height, condylar height, antegonial angle, antegonial depth, gonial angle, and the superior border of mental foramen were bilaterally measured as well as bicondylar and bigonial breadths using Scanora Lite. Correlation of parameters with gender was analyzed by univariate, multiple, and best models. All indices except for gonial angle were significantly different between males and females and can be used for gender determination according to univariate model. Condylar height, coronoid height, and superior border of mental foramen and ramus were still significantly greater in males than in females after controlling for the effect of confounders (p < 0.05). Based on the best model, a formula including five indices of bicondylar breadth, condylar height, coronoid height, minimum ramus width, and superior border of mental foramen was used for gender determination. Values higher than 56% indicate male gender, while lower values indicate female gender, with 81.38% specificity for correct detection of females and 88.97% sensitivity for correct detection of males. Despite the satisfactory results, future research should focus on larger populations to verify the accuracy of the present findings.

Sexual dimorphism in human facial expressions by 3D surface processing

Human face is a dynamic system where facial expressions can rapidly modify geometry of facial features. Facial expressions are believed to be universal across world populations, but only a few studies have explored whether grimacing is sexually dimorphic and if so to what extent. The present paper explores inter- and intra-individual variation of human facial expressions with respect to individual's sex based on a set of neutral and expression-varying 3D facial scans. The study sample composed of 20 individuals (10 males and 10 females) for whom 120 scans featuring grimaces associated with disgust, surprise, "u" sound, smile and wide smile were collected by an optical scanner Vectra XT. In order to quantify the dissimilarity among 3D images, surface comparison approach based on aligned 3D meshes and closest point-to-point distances was carried out in Fidentis Analyst application. The study revealed that sexual dimorphism was indeed one of the factors which determined the extent and characteristics of facial deformations recorded for the studied expressions. In order to produce a grimace, males showed a tendency towards extending their facial movements while females were generally more restrained. Furthermore, the facial movements linked to the wide smile and "u" sound were revealed as the most extensive relative to the other expressions, while the smile and surprise were shown indistinguishable from the neutral face.

The relationship between facial morphology, body measurements and socio-economic factors

Background and aim: The effect of socio-economic factors (living conditions) and parental smoking habits on development of facial morphology and body measurements was studied on a longitudinal Czech sample of 25 girls and 25 boys.

Subjects and methods: A set of studied digitalized photographs taken from 0.5 to 18 years in intervals of 6 months originated in the Brno Longitudinal Study. Facial shape changes of sub-adult participants were described using a configuration of 27 landmarks and further studied by using methods of geometric morphometric and multivariate statistics. In order to localize growth-related shape changes within the face, the studied region was divided into upper, middle and lower facial units and analyzed separately.

Results and conclusion: The results show that in the course of ontogenesis there is a strong correlation between facial shape change and body measurements, height included (r=0.10 and r=0.24 in boys and in girls, respectively). The pubertal spurt of the facial shape change rate was revealed at 10.5 years in girls and at 11.5 years in boys. The earlier onset of the pubertal rate increase in facial shape changes in boys was associated with records of poor living conditions. In addition, the mother’s smoking habits were linked to a noticeable facial shape change.

Cephalo-facial analysis to estimate stature in a Sudanese population

Medico-legal practitioners are often confronted with dismembered remains from which they need to develop a biological profile to establish identity. Accurate estimation of stature is an initial, crucial component of any meaningful medico-legal evaluation. However, sometimes only cephalo-facial remains are available. The most accurate statistical estimations of biological attributes are based on population-specific standards. Therefore, this study assessed the ability to estimate stature using 15 cephalo-facial measurements in 240 Sudanese adults (120 men, 120 women) aged 18-25years. Stature and cephalo-facial measurements of men were significantly higher than those of women. Most of the measurements were significantly correlated with stature (p<0.05), with better correlations for women than for men. The accuracy of stature estimation using sex-specific simple and stepwise multiple regression equations ranged from ±52.53 to ±60.28mm. This study provides new forensic standards for stature prediction in a Sudanese population. However, the equations should be used with caution in forensic cases when the more reliable body parts (e.g., limbs) are not available for human identification.

Introducing Computed Tomography Standards for Age Estimation of Modern Australian Subadults Using Postnatal Ossification Timings of Select Cranial and Cervical Sites(.)

Contemporary, population-specific ossification timings of the cranium are lacking in current literature due to challenges in obtaining large repositories of documented subadult material, forcing Australian practitioners to rely on North American, arguably antiquated reference standards for age estimation. This study assessed the temporal pattern of ossification of the cranium and provides recalibrated probabilistic information for age estimation of modern Australian children. Fusion status of the occipital and frontal bones, atlas, and axis was scored using a modified two- to four-tier system from cranial/cervical DICOM datasets of 585 children aged birth to 10 years. Transition analysis was applied to elucidate maximum-likelihood estimates between consecutive fusion stages, in conjunction with Bayesian statistics to calculate credible intervals for age estimation. Results demonstrate significant sex differences in skeletal maturation (p < 0.05) and earlier timings in comparison with major literary sources, underscoring the requisite of updated standards for age estimation of modern individuals.

Three-dimensional magnetic resonance imaging of velopharyngeal structures

PURPOSE

To report the feasibility of using a 3-dimensional (3D) magnetic resonance imaging (MRI) protocol for examining velopharyngeal structures. Using collected 3D MRI data, the authors investigated the effect of sex on the midsagittal velopharyngeal structures and the levator veli palatini (levator) muscle configurations.

METHOD

Ten Caucasian healthy adults (5 women and 5 men) participated. A whole-head 3D MRI scan was obtained while participants were at rest in the supine position. Basic anatomic parameters of the velopharynx including midsagittal velopharyngeal structures and levator muscle configurations were compared between sexes.

RESULTS

Detailed information on the 3D MRI protocol and data analysis method was introduced in the study. On the basis of the data, only the length of the levator muscle showed a statistically significant sex difference: Male participants had significantly longer levator muscles than those of female participants.

CONCLUSIONS

The present study successfully demonstrated the use of 3D MRI in quantifying major velopharyngeal structures and provided additional data on the anatomic variations that exist in healthy adult individuals.

Mandibular growth, remodeling, and maturation during infancy and early childhood

OBJECTIVE

To describe the growth, maturation, and remodeling changes of the mandible during infancy and early childhood.

MATERIALS AND METHODS

Seven Bolton-Brush Growth Study longitudinal cephalograms (N = 336) of each of 24 females and 24 males, taken between birth and 5 years of age, as well as early adulthood, were traced and digitized. Five measurements and nine landmarks were used to characterize mandibular growth, remodeling, and degree of adult maturity.

RESULTS

Overall, mandibular length showed the greatest growth changes, followed by ramus height and corpus length. Corpus length was the most mature of the three linear measures; ramus height was less mature than overall mandibular length. The greatest growth rates occurred between 0.4-1 year; yearly velocities decelerated thereafter. The ramus remodeled superiorly only slightly more than it remodeled posteriorly. Male mandibles were significantly (P < or = .05) larger, displayed greater growth rates, and were significantly less mature than female mandibles. There were no significant differences in mandibular growth or maturation between Class I and Class II patients.

CONCLUSIONS

The mandible displays decelerating rates of growth and a maturity gradient during infancy and early childhood, with males showing more growth and being more mature than females.

Cranial base growth in patients with Down syndrome: a longitudinal study

INTRODUCTION

The purpose of this study was to assess the growth of the cranial base in a sample of patients diagnosed with Down syndrome (DS).

METHODS

The sample comprised 47 subjects (25 boys, 22 girls) with DS. All patients had at least 2 x-rays that showed the cranial base. To make comparisons among age groups, the sample was divided into 3 groups: prepubescent (8-11 years), pubescent (12-14 years), and postpubescent (15-18 years). A control group included 38 normal subjects (22 boys, 16 girls, without DS) who were part of a longitudinal growth sample. Computerized cephalometric analysis was performed on all subjects, and cephalometric superimpositions were made. Two-way ANOVA was used to study the overall changes between groups. In addition, 1-way ANOVA and the Duncan multiple range test were used to analyze possible differences in the age groups.

RESULTS

Cranial base growth in patients with DS from age 8 to 18 was similar to that of the control group. Structural differences in the cranial base are established before 8 years of age and consist of shorter, flatter anterior and posterior bases.

The pattern of facial growth before and during puberty, as shown by French-Canadian girls

The results are reported for an analysis of longitudinal sequences of lateral head X-rays of 50 Montreal girls, taken annually between the ages of 6 and 15 years. Mean size changes for distances within the cranial base, the maxilla and the mandible, as well as those outlining the facial polygon, are displayed on a common proportional scale based on mean sizes at 15 years old. Mean growth velocities are displayed on both a chronological age scale and on one relative to the individual age of peak growth velocity in stature. A distinct facial pattern of growth is established, In terms of the proportion of final size achieved during childhood, it is below the cranial pattern, but above the general skeletal one. This facial pattern shows a pubertal peak in growth, but one quantitatively less important than that for stature. The timing of the two peaks is closely aligned, although the evidence favours a slightly later development for the face. The mandibular ramus provided the sole exception to this common facial pattern, though some questions on maxillary growth remain open.