Sexual dimorphism in mandibular morphometry: a comparative cone beam computed tomography study of Egyptian and Saudi populations

INTRODUCTION

The identification of age, sex, stature, and ethnicity is essential for constructing anatomical profiles from human remains [1]. It is less known to the general population that radiological methods are essential in fo-rensic science [2]. In the realm of maxillofacial dia­gnostics, cone beam computed tomography (CBCT), is rec-ognized as the pinnacle of medical imaging techniques [3].
In forensic records, the concealment of victim identities through means, such as amputation or mutilation, is not uncommon. However, if an adult skeleton is intact post-catastrophe, gender determination can be exe-cuted with absolute certainty [4]. The accuracy of gender determination using a complete skeleton range from 90% to 100% [5].
In mass disaster scenarios, the challenge of identification escalates with the presence of partial or frag-mented human remains [6]. This necessitates a spectrum of evaluative benchmarks tailored for diverse popu-lations. The study of craniofacial attributes has been a focal point in numerous forensic anthropology research endeavors [7]. For dimorphic bone structures, the need for precise and reliable analytical methods is para-mount, especially given the extensive examination of their morphological and molecular characteristics. The consistency and reproducibility of visible morphological and metric markers underscore the necessity of dependable differentiation techniques for fragmented dimorphic bones [8].
Sexual dimorphism is a prevalent trait among most bones, with the skull and pelvis being particularly dis-tinct, thereby rendering them critical for gender determination. In the absence of the skull, the mandible be-comes a crucial element for gender assessment [9]. Known as the strongest and most dimorphic bone of the skull, the mandible is pivotal for gender determination due to distinct maturation patterns in males and females [10]. The mandible, with its numerous gender-determining traits, aids in the identification of gender in uniden-tified remains. This is true even for remains that have been subjected to burning [1]. The mandible, especially the ramus, undergoes morphological, size, and remodeling changes due to masticatory forces, which are markedly diffe­rent between genders [11]. These characteristics make the mandible a valuable tool for gender identification in both living and deceased individuals [12].
In previous investigations, researchers have identified the posterior border of the ramus flexure as an indicator of gender, e.g., the pelvis [13]. Studies employing CBCT, orthopantomography, and dry mandibu-lar analyses, have demonstrated significant gender-based differences in osteometric parameters. These pa-rameters included mandibular length, bigonial breadth, bicondylar breadth, coronoid height, ramus height, and ramus breadth. Male dimensions are generally larger [14].
With the increasing availability of CT technology, the frequency of postmortem CT examinations has surged [11]. In maxillofacial applications in particular, CBCT serves as a specialized variant of medical CT [12]. CBCT is a 3D imaging technology for postmortem imaging by forensic professionals, particularly for skeletal assessments with submillimeter precision and minimal radia-tion exposure [3].

OBJECTIVES

The present study aimed to verify the precision of CBCT imaging in determining sex and gender dimor-phism in two different cohorts, i.e., Egyptian and Saudi, by analyzing the morphological characteristics of the mandibular bone, focusing in particular on the mandibular ramus dimensions. Comparison and quanti-tative measurements of mandibular ramus dimensions, such as the length, breadth, and height were per-formed in male and female samples, to ascertain distinct morphological differences.

MATERIAL AND METHODS

STUDY DESIGN

This retrospective study was conducted after obtaining ethical approval from the Faculty of Dentistry, Al-exandria University Ethics Committee (IORG0008839).
CBCT images were collected from radiology center (Department of Oral Medicine, Periodontology, Oral Diag-nosis and Oral Radiology, Faculty of Dentistry, Ale­xandria University, Egypt) for patients referred for radiogra- phic evaluation from March 2024 to December 2024.
The inclusion criteria for the study were: patients aged 21-60 years, with fully erupted mandibular dentition, absence of mandibular fractures, lesions, or pathologies, and CBCT images free from distortion or artifacts. Exclusion criteria were: patients with partially erupted or missing mandibular teeth, with fixed orthodontic appliances, having mandibular fixation screws or plates, and partial CBCT scans. Additionally, patients with systemic conditions affecting bone metabolism, congenital mandibular anomalies, or those who did not pro-vide informed consent or withdrew participation, were excluded. Informed consent was obtained from pa-tients, explaining the purpose of the study and the use of their existing CBCT images for research purposes, and ensuring confidentiality of their personal data. Participation was voluntary, and patients were assured they can withdraw from the study at any time.

SAMPLE SIZE ESTIMATION

Sample size was determined using G*Power software, version 3.1, with parameters set at effect size of 0.8,  level of 0.05, and power of 80%. This calculation showed a requirement of 30 CBCTs per subgroup, resulting in a total sample size of 120 CBCT scans. Participants were divided into two main groups: Saudi (Group 1) and Egyptian (Group 2), with each group further subdivided into two subgroups: 30 male and 30 female patients.

RADIOGRAPHIC MEASUREMENTS

All scans were performed using an i-CAT Next Generation CBCT unit (Imaging Sciences Internatio­nal, Hat-field, PA, USA), with standardized parameters: 120 kVp, 6 mA, 16 × 8 cm mandibular field of view, and a 26.9-second scan time at 0.25 mm resolution. DICOM data were analyzed using OnDemand 3D™ software (version 1.0.11.1007; Cybermed Inc., Seoul, South Korea).
Two calibrated and blinded examiners performed all measurements independently. Prior to the study, inter- examiner calibration was conducted using 10 random CBCT scans not included in the study sample. Following a collaborative calibration session, the two experienced observers independently analyzed CBCT images. To minimize inter- and intra-observer variability, each exa­miner repeated the measurements during two distinct sessions, with two weeks interval, to assess both intra- and inter-observer reliability. The tasks of randomization and blinding were managed by a separate operator, who was not involved in the measurement process. 3D view window was maximized to ensure optimal visualization of the mandible. Segmentation was initiated using a segmentation knife tool, located on the left side of the ope­rator’s screen, to isolate the left or right hemi-mandible. The knife was used to cut 25 cm-long segments from the skull, en-suring consistent and precise segmentation. To standardize the measurements, three reference lines were drawn: first at the highest point of the condylar head, second at the highest point of the coronoid process (to determine their most cranial extent), and third at the angle of the mandible. These reference lines served as anato­mical landmarks for accurate measurement. The desired values were then measured in millimeters (mm) using a ruler tool provided by the software. This methodology ensured consistency and reproducibility in the evaluation of mandibular ramus indices. Subsequently, the following measurements were performed on the CBCT images (Figure 1), as outlined by previous studies [7, 15].
A. Projective ramus height (PrRHt): Projective height of ramus between the highest point of the mandibular capitulum (condylion) and lower margin of the bone (gonion).
B. Maximum ramus breadth (MaxRBr): Distance between the most anterior point on the mandibular ramus and a line connecting the most posterior point on the condyle and the angle of jaw.
C. Minimum ramus breadth (MinRBr): Smallest ante­rior-posterior diameter of the ramus.
D. Condylar height (ConHt): Height of the condylar process from the condylon to the plane at the deepest point of the sigmoid notch.
E. Coronoid height (CoHt): Measured along the coronoid process’ long axis, running from the coronoid point to the sigmoid notch plane.
In the 3D volumetric rendering, bigonial breadth (BGoBr) was measured as the direct linear distance be-tween the left gonion (Go-L) and right gonion (Go-R). Gonions were identified as the most inferior, posterior, and lateral points on the mandibular angles. Measurements were performed using the ruler tool in the axial view, ensuring accurate and reproducible results.
F. Bigonial breadth (BGoBr): Direct distance between the gonions of both the left and right sides (Figure 2).
S. Superior mental foramen (SMeF): On the coronal view, the vertical distance from the superior end of the mental foramen to the midpoint of the lower border of the mandible at the point of maximum curva-ture was measured (Figure 3).
I. Inferior mental foramen (IMeF): On the coronal view, the vertical distance from the inferior end of the mental foramen to the midpoint of the lower border of the mandible at the point of maximum curva-ture was measured (Figure 3).

STATISTICAL ANALYSIS

Statistical analysis for the obtained data was performed using IBM SPSS version 20.0 software. Data nor-mality was assessed using the Shapiro-Wilk test. Descriptive statistics included range, mean, standard devia-tion, and median. Student’s t-test was applied to compare normally distributed variables between groups, with 95% confidence intervals calculated for mean differences. Statistical significance was set at p < 0.05.

RESULTS

The agreement analysis of inter-examiner was assessed using intraclass correlation coefficient (ICC), with measurements repeated after two weeks to determine intra-examine reliability. The ICC values showed excel-lent agreement ( > 0.90) for both inter- and intra- examine reliability.
Table 1 presents the comparative analysis of mandibular ramus measurements between Egyptian males and females. Statistical analysis demonstrated significant sexual dimorphism in most parameters, with males exhibiting larger dimensions. Significant sexual dimorphism was observed in several mandibular parameters. Males exhibited greater MaxRBr (43.79 ± 4.11 mm) compared with females (39.54 ± 2.69 mm, p < 0.001). Similarly, ConHt was significantly higher in males (14.99 ± 2.97 mm) than in females (13.46 ± 1.99 mm, p = 0.023). CoHt followed the same trend, with males showing larger measurements (14.42 ± 2.81 mm) compared with females (11.51 ± 2.74 mm, p < 0.001).
However, no statistically significant differences were observed in MinRBr (p = 0.417), mental superior height (p = 0.441), or mental inferior height (p = 0.243). The ramus height was notably greater in males (60.49 ± 10.07 mm) than in females (56.58 ± 4.30 mm, p = 0.040). Also, the BGoBr demonstrated significant differ-ences, with males measuring 97.87 ± 9.32 mm compared with 86.06 ± 4.21 mm in females (p < 0.001).
Among the Saudi population, significant sex differences were observed in CoHt and mental inferior height. Males exhibited greater CoHt (14.33 ± 4.01 mm) than females (11.10 ± 2.34 mm, p < 0.001). Mental inferior height was also significantly higher in males (14.29 ± 1.17 mm) compared with females (12.60 ± 1.67 mm, p < 0.001). In contrast, ConHt and SMeF distance showed slightly larger values in males compared with females, though these differences were not statistically significant. Ramus height was significantly larger in males (65.46 ± 5.63 mm) than in females (57.27 ± 3.72 mm, p < 0.001), and BGoBr was simi- larly greater in males (90.85 ± 3.94 mm) than in females (84.47 ± 4.23 mm, p < 0.001). However, no statisti-cally significant differences were found in MaxRBr (p = 0.222), MinRBr (p = 0.969), ConHt (p = 0.725), or men-tal superior height (p = 0.159) (Table 2).
Significant differences were observed in mandibu­lar measurements between both Egyptian and Saudi males. Egyptian males demonstrated significantly larger dimensions in three measurements: MaxRBr, MinRBr, and BGoBr. Conversely, Saudi males exhibited greater ConHt (17.24 ± 3.63 mm) compared with their Egyptian counterparts (14.99 ± 2.97 mm, p = 0.012). Ramus height was also significantly larger in Saudi males (65.46 ± 5.63 mm) than Egyptian males (60.49 ± 10.07 mm, p = 0.023). However, CoHt, mental supe- rior height, and mental inferior height showed no significant differences between the two populations (Table 3).
Most parameters presented no statistically significant differences between the two female populations, including CoHt and SMeF distance. However, two measurements demonstrated significant differences: MinRBr was significantly larger in Egyptian females, while ConHt was significantly greater in Saudi females. No significant differences were observed in MaxRBr (p = 0.115), CoHt (p = 0.528), mental superior height (p = 0.507), mental inferior height (p = 0.124), ramus height (p = 0.493), or BGoBr (p = 0.288) (Table 4).

DISCUSSION

The current study aimed to evaluate the role of mandibular morphometry in sex determination within both the Egyptian and Saudi populations, contributing to the broader field of forensic anthropology. Our findings demonstrated significant sexual dimorphism in key mandibular measurements, such as ramus height, condylar width, and BGoBr. The CBCT images were collected from one radiology center to ensure standardiza-tion in imaging protocols, patient positioning, and equipment settings. This enhances the internal consistency of measurements that minimizes variability in image quality and resolution. Additionally, the center delivers services for patients from both the studied populations, providing a balanced and representative sample that enhances the generalizability of the study findings.
The results of this study align with previous research, demonstrating that mandibular dimensions, such as ramus height, ConHt, and gonial angle, show significant sexual dimorphism, supporting their utility in forensic science [16]. Our findings are similar to those of Esfehani et al. [17], who reported that measurements, in-cluding condylar and CoHt as well as ramus width, exhibited marked differences between male and female mandibles in an Iranian population. This study highlighted that males consistently presented larger ramus dimensions, with a sensitivity of 88.97% and spe­cificity of 81.38% in gender classification, reinforcing the accuracy of mandibular indices in sex determination. Another study conducted among Turkish population reported that CBCT mandibular ramus variables showed a statistically significant difference among both genders [8].
Additionally, while BGoBr measurements demonstrated some variation, their combined use with ramus height and breadth resulted in improved accuracy, reinforcing their combined potential in forensic applica-tions. An Egyptian population study by Abd et al. [18] further confirmed the use of CBCT in capturing mandibular dimorphism, emphasizing the value of advanced imaging technologies in forensic odontology. This coincides with the findings of our study, indicating that even slight differences in mandibular structure can provide critical estimations in gender identification.
In agreement with previous studies [18-20], males exhibited larger ramus and ConHt compared with fe-males. A significant difference was observed for the mandibular condyle height on both sides between both genders. This pattern reflects general trends in skeletal development, where males tend to have more pro-nounced and robust mandibles due to increased masticatory forces and hormonal influences during growth [20]. Such differences are critical for forensic investigations, as they enable sex estimation with con-siderable accuracy when analyzing skeletal remains.
While the overall trends in sexual dimorphism were similar between both the Saudi and Egyptian popula-tions, specific differences were observed in certain mandibular measurements. In the Saudi population, males displayed greater ramus height than females, consistent with findings in Egyptian cohorts. These findings align with the results reported by de Oliveira et al. [21], who investigated the length of mandibular ramus as an indicator of age and sex in a Brazilian population. Their study demonstrated that sex could not be reliably determined based on the mandibular ramus length measurements until the age of 18 years. Furthermore, they found that the accuracy of sex determination using late­ral cephalometric radiographs was limited to only 54%. This finding suggests that, compared with conventional CT or X-ray imaging, CBCT enhances the effectiveness of the ramus length as a tool for sex identification.
However, the mean ramus height in Saudi males was slightly more than that reported for Egyptian males in our study. This discrepancy may be influenced by genetic, environmental, and dietary factors, which contribute to variations in skeletal morphology between the populations. Holmes and Ruff [22] emphasized the influence of dietary factors on human mandible de-velopment. Similarly, Silva et al. [23] and Ichijo et al. [24] highlighted the role of ethnicity in shaping mandib-ular development and measurements. Additionally, Filho et al. [25] demonstrated that stressful lifestyles can impact both the development and function of the mandible.
A marked difference in BGoBr was observed between the two populations. Saudi males exhi­bited larger gonial BGoBr than females, a trend consistent with Egyptian data. However, the degree of sexual dimorphism in BGoBr was more pronounced in the Egyptian population. This may reflect differences in craniofacial growth patterns, masticatory function, and age-related re- modeling processes. Gamba et al. [26] showed higher mean BGoBr values for males than females in a Brazilian population. Similar results were observed by Leversha et al. [27] in an Australian population, El-Sherbiny et al. [14] in an Egyptian population, and Rad et al. [28] in an Iranian population. Both males and females exhibited larger BGoBr in the Egyptian than Saudi populations.
In agreement with other studies [17, 20, 29], the ConHt was greater in males than females in both the studied populations. Rad et al. [28] investigated several mandibular parameters in an Iranian population, and observed significant differences between males and females; they identified ramus height, bicondylar breadth, and CoHt as the most reliable parameters for gen-der determination. In our study, Saudi males and females had greater ConHt than the Egyptian population. This finding emphasizes the reliability of ConHt as a consistent indicator of sexual dimorphism among diverse populations [17].
Maximum ramus width showed possibility for gender determination in the Egyptian population, while minimum ramus width did not demonstrate differences between males and females in both the studied co-horts. Although these parameters can be utilized for sex determination, they exhibit limited sensitivity and specificity. These findings are consistent with previous studies reported in the literature [14, 30].
In the present study, the vertical position of the mental foramen was assessed relative to the superior and inferior border of the mandible. However, no significant differences were observed between males and fe-males in either the Egyptian or Saudi populations for this parameter. These findings indicate that the mental foramen posi-tion may not be a reliable indicator for gender determination in these populations. While a previous study [17] suggested that the mental foramen position could theoretically be used for gender determination with 75% probability for its inferior border and 78% probability for its superior border, its practical efficacy is limited due to its low sensitivity and high specificity. Particularly, it was more accurate for identifying females than males.
The variations in mandibular measurements observed in our study between both the populations can be attributed to a combination of genetic, environmental, and lifestyle factors. Ethnic variations in craniofacial features are well-documented, with differences in diet and masticatory habits shaping mandibular adapta-tions over time [17]. Additionally, genetics and developmental factors play a key role in influencing the mandibular size and shape, highlighting the importance of establishing forensic standards tailored to specific populations [18].
The findings of this study emphasize the importance of developing localized forensic reference data to enhance the accuracy of sex determination. Although mandibular measurements provide valuable infor-mation, their predictive accuracy may vary across populations. Determining population-specific benchmarks is essential for minimizing errors in forensic identification, especially in regions with diverse ethnic composi-tions. Our findings highlight the importance of mandibular measurements in forensic identification, particu-larly ramus height, condylar width, and BGoBr as key indicators of sex.
This study offers several strengths, which enhance its scientific value. First, it utilizes CBCT that delivers accurate, three-dimensional, and non-invasive imaging for craniofacial morphometric analysis, providing higher precision compared with traditional two-dimensional radiographs. Second, the use of standardized anatomical landmarks and calibrated measurements ensures the reliability and reproducibility of the data.
Importantly, a key strength of this study is the comparative analysis between two distinct populations (i.e., Egyptian and Saudi), which enhances the forensic relevance of the findings. By identifying popula-tion-specific anatomical differences, the study provides valuable reference data that can improve the accuracy of sex determination in forensic cases across different ethnic groups. This cross-population comparison adds to the novelty and applicability of the research in multiethnic forensic contexts.
However, the limitation of the present study is its retrospective design, which may be subject to selection bias, limiting the control over confounding variables. Additionally, the study relied solely on CBCT scans for morphometric analysis. While CBCT provides high-resolution, three-dimensional imaging of bony structures, it does not capture soft tissue characteristics, which may contribute to a more comprehensive forensic profile. Moreover, the relatively small sample size for each population may affect the broader applicability of the results. To strengthen these findings, future research should focus on larger and more diverse popula-tions to better validate the use of mandibular indices across different ethnic groups. Additionally, collecting scans from a single institution may limit the external validity of the results, as the findings may not fully rep-resent variations across different populations or clinical settings. Future multicenter studies with larger and more diverse samples are recommended to improve the gene­ralizability and confirm the applicability of the findings in broader forensic and clinical contexts.

CONCLUSIONS

This study demonstrates significant sexual dimorphism in mandibular dimensions among both Egyptian and Saudi populations. Specifically, Egyptian males presented larger maximum and minimum ramus breadth, whereas Saudi males had notably greater condylar and ramus heights. In females, similar differences were observed, with Egyptian females showing greater minimum ramus breadth, and Saudi females exhibiting higher condylar height. These population-specific variations emphasize the necessity for tailored forensic guidelines, which reflect unique ethnic characteristics, ultimately enhancing the accuracy of forensic identifi-cation practices.

DISCLOSURES

1. The approval of the Bioethics Committee for the research: This retrospective study was conducted after obtaining ethical approval from the Faculty of Den-tistry, Alexandria University Ethics Committee (IORG0008839).
2. Assistance with the article: None.
3. Financial support and sponsorship: None.
4. Conflicts of interest: None.

References