Sexual dimorphism in mental foramen position: A discriminant function study in the Malay population

Abstract

Objectives

The mandible has emerged as a pivotal structure for sex estimation in forensic contexts due to its exceptional postmortem preservation and pronounced sex-linked morphological variation. Among the anatomical landmarks on the mandible, the mental foramen has garnered significant attention due to its metric consistency and resistance to age-related resorption, making it an ideal candidate for population-specific morphometric analyses. This study aimed to rigorously evaluate sexual dimorphism in the spatial relationship between the mental foramen and mandibular lower border within the Malay population by applying advanced discriminant function analysis to derive a high-specificity forensic sex estimation tool.

Methods

A retrospective cohort study was conducted using 141 high-resolution digital orthopantomograms from the Malay population comprising 71 females and 70 males, thereby ensuring a nearly equal sex distribution for discriminant function analysis. Linear distances from the superior (S–L) and inferior (I–L) borders of the mental foramen to the mandibular lower border were measured bilaterally. Discriminant function analysis was conducted to develop a sex classification model, which was validated based on cross-validation and comparative statistical metrics.

Results

Significant sexual dimorphism was observed across all measurements (p < 0.001), where males had larger mean distances compared with females. The derived discriminant function achieved a classification accuracy of 75.18 %, where the left I–L had the highest discriminatory power (standardized coefficient = 0.488). Canonical correlation analysis (0.523) and Wilks' lambda (0.726) confirmed the model's robustness.

Conclusion

In this study, the first population-specific discriminant equation for sex estimation in Malays was established, addressing a critical gap in forensic anthropology. The findings highlight the need for ethnic-specific morphometric standards, and provide a reproducible tool for forensic applications.

Introduction

Sexual dimorphism conventionally refers to the physical differences between males and females of a species due to intricate relationships among genomic, gonadal, hormonal, and behavioral influences. This variability is vital for sustaining diverse phenotypic qualities and plays a crucial role in forensic investigations.¹

The mandible is one of the most resilient and durable bones, and it has been widely analyzed due to its potential use for assessing sexual dimorphism because of distinct morphological and metric variations between males and females.² The mental foramen is particularly significant among mandibular landmarks because its position relative to the inferior border of the mandible remains stable due to the negligible resorption of basal bone. Consequently, the distance from the mental foramen to the mandibular border is considered more reliable than that to the alveolar crest, and thus it is employed as a robust, age-independent reference in forensic anthropology.3, 4, 5

Sex estimation can be performed using two principal methods: nonmetric methods based on visual assessments of skeletal traits and metric methods based on quantitative measurements analyzed using statistical models. Metric methods, particularly those based on discriminant function analysis (DFA), provide objective and reproducible approaches for sex estimation, enhancing forensic reliability.⁶

Previous studies have demonstrated that the mental foramen exhibits sexual dimorphism, where the vertical and horizontal distances from the inferior border of the mandible are generally greater in males compared with females.⁷ At present, there is a lack of curated skeletal reference collections with comprehensive demographic documentation in Malaysia. Consequently, radiographic imaging can provide a practical and ethically acceptable alternative for developing contemporary, population-specific forensic standards using routinely acquired clinical data.⁸ Within this context, imaging modalities such as orthopantomograms (OPGs) and cone-beam computed tomography (CBCT) have been employed to analyze these differences, providing reliable and reproducible measurements for forensic investigations.⁶

OPGs provide a standardized, non-invasive, and cost-effective modality for assessing mandibular landmarks, with substantially lower radiation exposure compared with CBCT and routine availability in dental practice. Panoramic radiography also captures the maxillary and mandibular arches with their supporting structures in a single tomographic image, demonstrating its value for forensic research.⁹ The foramen is visible as a radiolucent area in panoramic radiographs.

Numerous studies conducted around the world have tried to estimate sex based on the anatomical position of the mental foramen.^2,10, 11, 12, 13 However, despite generally favorable accuracy rates, these studies demonstrate that considerable inter-population variability exists in both the measured values and discriminant power, suggesting that models developed in one ethnic group cannot be directly transferred to another. In Malaysia, only a limited number of studies have investigated sex estimation based on the anatomical positioning of the mental foramen. Malaysia is a multi-ethnic nation mainly comprising Malay, Chinese, and Indian populations, and thus several studies have attempted to evaluate both racial variations and sexual dimorphism in the location of the mental foramen, but these studies found no significant differences in its anatomical position among the three ancestral groups.¹⁴ However, these studies relied primarily on categorical positional assessments rather than precise metric distances from stable basal landmarks, limiting their applicability for discriminant modeling.

Ngeow et al. identified the most common mental foramen position in Malays as aligning with the longitudinal axis of the second premolar.¹⁵ Alias et al. examined the relationship between mental foramen location and sex across populations, but they did not perform subgroup analysis for each ethnicity.¹⁶ More recently, Renjith et al. conducted a study specifically in the Malaysian Chinese population, providing valuable population-specific insights into the application of DFA for sex estimation using mental foramen positioning.¹⁷

A validated discriminant function tailored specifically to the Malay population is lacking at present. Craniofacial morphology varies in a population-specific manner due to the influences of genetic ancestry, developmental patterns, and environmental factors. In Southeast Asian populations, including Malays, distinct differences in cranial and mid-facial structures have been attributed to unique growth trajectories and historical admixture.⁸ These variations highlight the complexity of forensic ancestry assessment in multi-ethnic regions such as Malaysia.

Anatomical diversity has important forensic implications because population-specific craniofacial traits can influence the expression of sexual dimorphism and the performance of metric classification models. Consequently, applying reference standards or discriminant functions derived from other ethnic groups may reduce the accuracy, highlighting the need for forensic frameworks tailored to the Malaysian context and validated in the population.

Considering these issues, the present study aimed to address the lack of a Malay-specific, metric-based discriminant model for sex estimation by quantifying sexual dimorphism in the vertical position of the mental foramen relative to the mandibular lower border in a Malay population sample. A population-specific discriminant function was developed for forensic sex estimation, and the model's performance and reliability were evaluated based on rigorous statistical testing and cross-validation.

Materials and Methods

Study design and ethical compliance

This retrospective observational study was approved by the Institutional Ethical Committee of Manipal University College Malaysia (MUCM/Research and Ethics Committee – 006/2023). Anonymized digital panoramic radiographs were retrieved from the university's Department of Oral Medicine and Radiology archives.

Radiographic images were obtained using a Planmeca Promax 3Ds imaging unit (Helsinki, Finland). To ensure optimal image quality, an experienced evaluator meticulously assessed all of the acquired radiographs before applying a rigorous selection procedure based on predefined inclusion and exclusion criteria.

Sample selection

The study included high-quality radiographs of dentulous patients aged ≥20 years, where a separate-type mental foramen (distinctly positioned, non-fused) was clearly visible.

Radiographs were excluded if they contained artifacts or lesions obscuring the mental foramen, if patients had a history of mandibular surgical procedures, pathological conditions, or congenital anomalies, or if they were partially or completely edentulous. In addition, individuals aged less than 20 years and radiographs where the mental foramen was not distinctly identifiable were excluded.

Calibration

Two observers who were both specialists in oral pathology conducted the morphometric analysis. They underwent a structured and standardized calibration program under the direct supervision of an expert oral radiologist. This program standardized the identification of anatomical landmarks consisting of the superior and inferior borders of the mental foramen and the inferior mandibular border, as well as the protocol for placing measurement lines and using the software measurement tools.

Calibration was performed based on a dedicated validation set of 12 OPGs (six males and six females), which were randomly selected and not included in the main study cohort.

The following protocol was implemented to minimize and assess intra- and inter-observer variability:

• •Both observers were blinded to the subject's sex;
• •Each observer performed triplicate measurements for all parameters;
• •The mean of the three readings was calculated for each observer;
• •The final value of each measurement was obtained by averaging the means of both observers.

Intra-observer reliability was assessed by repeating measurements of the same 12 validation OPGs after a two-week interval. Inter-observer reliability was evaluated by comparing the initial measurements made by both observers of these validation images. Intraclass correlation coefficient analysis indicated excellent agreement, confirming the reliability of the measurement, and data collection then proceeded for the main study.

Final cohort

The final cohort comprised 141 OPGs (70 males: mean age = 40.48 ± 11.8 years; 71 females: mean age = 37.8 ± 7.79 years), maintaining a near-perfect 1:1 sex ratio to minimize demographic bias in our discriminant analysis.

Morphometric analysis protocol

Imaging analysis

The superior and inferior borders of the mental foramen were identified, and tangential lines were marked on digital radiographs by using the measuring and drawing tools in Romexis software (Version: 3.0.1.R). Perpendicular lines were drawn in alignment with the tangential lines, extending to the inferior border of the mandible on both the right and left sides. Before recording measurements, the software was calibrated to ensure accuracy. To minimize intra- and inter-observer variability, two blinded investigators obtained triplicate measurements of:

• •S–L: Superior mental foramen border to mandibular inferior border;
• •I–L: Inferior mental foramen border to mandibular inferior border;

and the mean of their three readings was calculated. The final measurement was obtained by averaging the means for both investigators.

The superior border of the mental foramen on the right side was taken as the reference point, and its distance to the inferior mandibular border (S–L) was measured. Similarly, the distance from the lower border of the mental foramen to the inferior border of the mandible (I–L) was recorded. The technique was then repeated for the left side, and the corresponding measurements were recorded (Figures 1 and 2).

Figure 1.

Panoramic radiograph illustrating the tangents and perpendiculars drawn to measure the distances between the reference points: superior border of mental foramen, inferior border of mental foramen, and lower border of mandible.

Figure 2.

Schematic diagram showing the mental foramen on the right and left sides. Red horizontal lines represent the superior and inferior border tangents of mental foramina on the right side. Green horizontal lines represent the superior and inferior border tangents of mental foramina on the left side. Red vertical lines represent distance between superior border of foramen and lower border of mandible. Green vertical lines represent distance between inferior border of foramen and lower border of mandible.

Statistical analysis

Data were statistically analyzed using SPSS version 30. Descriptive measures were computed including the mean and standard deviation. Independent t-tests were performed to assess differences in the measurements between sexes and anatomical landmarks. DFA was then conducted to evaluate the predictive strength of each variable for determining sex. Key statistical indicators such as canonical correlation, Wilks’ lambda, standardized and unstandardized discriminant function coefficients, structure matrix correlations, and group centroids were examined. The discriminant score (Z) was calculated using the derived equation:

$$\mathrm{Z}=\mathrm{a}+{\mathrm{W}}_1{\mathrm{X}}_1+{\mathrm{W}}_2{\mathrm{X}}_2+{\mathrm{W}}_3{\mathrm{X}}_3+\dots +{\mathrm{W}}_{\mathrm{i}}{\mathrm{X}}_{\mathrm{i}}$$

where:

Z = discriminant score

a = a constant

W = discriminant coefficient for the independent variable

X = Independent variable

i = number of predictor variables

The discriminant function's classification threshold was determined by computing the optimal cutting score (Z_CE) as the arithmetic mean of the male (Z_A) and female (Z_B) group centroids. Specimens with discriminant scores exceeding Z_CE were classified as male and those below the threshold as female. Statistical significance was established at p < 0.01 to ensure robust group differentiation.

Normality testing was performed for all mandibular measurements (right/left S–L and I–L) using Shapiro–Wilks’ test (p > 0.05), as well as visual examination of Q–Q plots and frequency distributions. The distributions of these variables were normal for both sexes. Subsequently, independent samples t-tests were conducted to evaluate potential sex-based differences in the mandibular parameters within the study cohort.

Homogeneity of variance was confirmed for all mandibular measurements (right/left S–L and I–L) using Levene's test (p > 0.05), thereby satisfying a key assumption before parametric analysis. Sex classification was performed using discriminant analysis, with bilateral S–L and I–L measurements as predictor variables.

Results

Statistical assumption checks

Data met the required assumptions for analysis.

Levene's test confirmed equal variance between sexes for all measurements (p > 0.01), as shown in Table 1.

Table 1.

Summarises the Levene's test for homogeneity of variances. S-L: Superior mental foramen border to mandibular inferior border. I-L: Inferior mental foramen border to mandibular inferior border.

	Levine Statistic	df1	df2	Significance
RIGHT SL-IL	0.543	1	139	0.462
LEFT SL-IL	2.178	1	139	0.142

The Shapiro–Wilk test indicated that female data and male right-side data (p > 0.05) were normally distributed, but not male left-side data, as shown in Table 2.

Table 2.

Summarises the Shapiro–Wilk test of normality. S-L: Superior mental foramen border to mandibular inferior border. I-L: Inferior mental foramen border to mandibular inferior border.

	Sex	Statistic	df	Sig.
Right SL-IL	Female	0.983	71	0.142
	Male	0.947	70	0.005
LEFT SL-IL	Female	0.954	71	0.011
	Male	0.935	70	0.001

The mean distances from the superior and inferior borders of the mental foramen to the mandibular inferior border are shown in Table 3 separately for both sexes. All four measurements were significantly higher in males than females.

Table 3.

Descriptive statistics of mental foramen in both sexes. S-L: Superior mental foramen border to mandibular inferior border. I-L: Inferior mental foramen border to mandibular inferior border.

Ethnicity	Variable	Male	Female	T (df)	P value
		Mean (SD)	Mean (SD)
Malay	Right S-L	16 (1.98)	14.01 (1.82)	6.187 (139)	<0.01
	Left S-L	15.92 (1.84)	14.05 (1.81)	6.062 (139)	<0.01
	Right I-L	13.47 (1.98)	11.54 (1.65)	6.274 (139)	<0.01
	Left I-L	13.5 (1.67)	11.71 (1.75)	6.166 (139)	<0.01

In males, no statistically significant difference was observed between right S–L (16.00 mm) and left S–L (15.92 mm) (p-value- 0.81).

In females, right S–L (14.01 mm) and left S–L (14.05 mm) also did not differ significantly (p = 0.89).

The average superior border to lower mandibular border distance was 15.96 mm in males and 14.03 mm in females, indicating consistent sexual dimorphism.

In males, the right I–L (13.47 mm) and left I–L (13.50 mm) did not differ significantly (p = 0.92).

In females, the right I–L (11.54 mm) and left I–L (11.71 mm) also did not differ significantly (p = 0.58).

The average inferior border to lower mandibular border distance was 13.49 mm in males and 11.63 mm in females, again indicating consistent sexual dimorphism.

Discriminant analysis was used to categorize sex and to derive the discriminant equation. This equation was formulated using unstandardized regression coefficients derived from the analysis.

$$\mathrm{Z}=–8.759+0.115\left(\text{Right}\mathrm{I}–\mathrm{L}\right)+0.207\left(\text{Right}\mathrm{S}–\mathrm{L}\right)+0.042\left(\text{Left}\mathrm{S}–\mathrm{L}\right)+0.284\left(\text{Left}\mathrm{I}–\mathrm{L}\right)\text{.}$$

The group centroids were Z_A (male) = 0.614 and Z_B (female) = −0.606. The classification threshold (Z_CE) was calculated as the arithmetic mean of Z_A and Z_B: Z_CE = (0.614 + (−0.606))/2 = 0.004, which was used as the cutoff for sex classification. Specimens with Z ≥ 0.004 were classified as male and those with Z < 0.004 as female.

The complete statistical parameters for the canonical discriminant functions, including structure matrix correlations and group centroids, are comprehensively presented in Table 4.

Table 4.

Summary of canonical discriminant functions of original sample. S-L: Superior mental foramen border to mandibular inferior border. I-L: Inferior mental foramen border to mandibular inferior border.

Variable	Unstandardized coefficient	Standardized coefficient	Structure matrix correlation
Right I-L	0.115	0.210	0.866
Right S-L	0.207	0.395	0.854
Left S-L	0.042	0.078	0.851
Left I-L	0.284	0.488	0.837
A (constant)	−8.759
Group centroid (male)	0.614
Group centroid (female)	−0.606
Canonical correlation	0.523
Wilk's lambda	0.726		<0.001

Statistical analysis indicated significant separation between the group centroids (p < 0.05), where a discriminant threshold of zero was used as the classification boundary: specimens scoring ≥0 were categorized as male and those scoring <0 as female. Standardized coefficients and structure matrix correlations indicated variable contributions to the discriminant function, where left I–L was identified as the most influential predictor followed by right S–L, left S–L, and right I–L in that order.

The canonical correlation coefficient of 0.523 (R² = 0.2735) indicated that 27.35 % of the variance in sex determination could be explained by the mandibular parameters. In particular, inferior border–based measurements contributed more strongly to this variance than superior border–based ones, suggesting their greater relevance to sexual dimorphism. This interpretation was reinforced by the comparatively lower Wilks’ lambda value (λ = 0.726) for inferior border measurements, which reflected the lower unexplained variance and highlighted their superior power in distinguishing between sexes.

Table 5 shows the classification accuracy results obtained for the discriminant function model for predicting sex based on the distances from the inferior border of the mandible to the superior and inferior borders of the mental foramen on both sides. Among the 141 cases analyzed, the model correctly classified 51 out of 70 males (72.86 %) and 55 out of 71 females (77.46 %), yielding an overall accuracy of 75.18 %. The identical classification accuracy obtained during cross-validation further validated the robustness of the DFA model.

Table 5.

Percentage of correct classification in original grouped cases, cross-validated grouped cases.

	Male		Female		Accuracy
	No. of cases	No. correctly classified (%)	No. of cases	No. correctly classified (%)	Total No. of cases	%
Original grouped cases	70	51	71	55	106/141	75.18
Cross-validated grouped cases	70	51	71	55	106/141	75.18

Discussion

Sex estimation remains a cornerstone of forensic anthropology and medico-legal investigations, especially in cases involving fragmented or incomplete human remains. The aim of the present study was to validate mandibular morphometric parameters for sex determination by examining the anatomical relationship between the mental foramen and the lower border of the mandible in samples from the Malay population in Malaysia. The selected parameters are forensically valuable because of their relative resistance to age-related morphological changes, thereby preserving their positional consistency throughout adulthood.18, 19, 20

Our analysis based on digital panoramic radiographs detected significant sexual dimorphism in both the superior and inferior linear distances from the mental foramen to the mandibular inferior border, where males had consistently higher mean values compared with females. These findings agree with those obtained in previous studies. In particular, studies by Renjith et al., Alias et al., Gupta et al., and Vodanovic et al. also found significantly greater distances from the inferior border of the mandible to the inferior margin of the mental foramen in males, thereby highlighting the reliability of this morphometric relationship as a discriminative marker for sex estimation.^16,17,21,22

DFA was conducted to develop a predictive model. A key result was that the structure matrix correlations for all four predictor variables were high and similar, ranging from 0.837 to 0.866, indicating that the superior and inferior vertical distances on both sides contributed in a substantial and collective manner to the model's discriminatory power, and no single measurement was a uniquely dominant predictor. This finding of bilateral metric symmetry is a notable population-specific characteristic, and it differs from patterns observed in other groups, such as in Malaysian Chinese, where Renjith et al. showed that left S–L often predominated as the primary predictor, reflecting population-specific mandibular growth trajectories.¹⁷ These findings highlight the importance of developing locally derived discriminant functions, as demonstrated by a study of indigenous South African skeletal samples by Franklin et al. who showed that population-specific equations significantly improved the accuracy of sex classification.²²

In the present study, both the superior (S–L) and inferior (I–L) mental foramen-to-mandibular lower border distances exhibited consistent sexual dimorphism, where males had higher mean values than females. No statistically significant right–left differences were observed for either parameter in males or females. This bilateral metric symmetry, combined with the high and similar structure matrix correlations obtained from DFA, indicates that sexual dimorphism is expressed consistently across multiple stable landmarks in this population, collectively enhancing the model's power.

Despite this symmetry, DFA identified the left inferior mental foramen-to-lower border distance (left I–L) as the strongest predictor of sex, suggesting that subtle population-specific morphological variations may enhance its discriminatory potential. These findings differ from those reported by Singal et al. who found no significant sexual dimorphism in the inferior mental foramen-to-mandibular border distance, despite observing significant differences in measurements involving the alveolar ridge.²³ This discrepancy may be explained by differences in population characteristics, landmark selection, and the inclusion of alveolar ridge-dependent parameters, which are more susceptible to age-related remodeling and dental status.

Therefore, the use of basal bone landmarks, as in the present study, may provide a more stable foundation for sex estimation in adults. The significantly greater dimensional ranges observed in males for both S–L and I–L measurements allowed the establishment of an optimal classification threshold, facilitating reliable sex estimation from isolated mandibular specimens and providing a statistically validated tool for forensic applications involving limited skeletal material.

In the present study, the discriminant function model based on vertical distances from the inferior border of the mandible to the superior and inferior margins of the mental foramen had an overall classification accuracy of 75.18 %. This accuracy remained consistent during cross-validation, indicating the model's robustness and reliability. In particular, the model correctly identified 72.86 % of males and 77.46 % of females in a sample of 141 subjects. Importantly, the canonical correlation coefficient of 0.523 (R² = 0.2735) indicated that approximately 27.35 % of the variability in sex could be explained by the four mandibular parameters used in the model, and thus 72.65 % of the variability was potentially influenced by other skeletal, genetic, environmental, or dietary factors.

Similarly, Wilks' lambda (λ = 0.726 in this study) provided a measure of how well the discriminant function could distinguish between sexes. Wilks’ lambda values closer to zero indicate stronger separation, whereas values closer to one suggest weaker separation. The λ value of 0.726 suggests a moderate discriminatory capacity, which was consistent with the observed classification accuracy, demonstrating that the mental foramen position is a useful marker but it does not fully capture all sex-based variation. By contrast to the higher canonical correlation of 0.653 explaining 42.64 % of the variance in sex estimation reported by Renjith et al., the lower value observed in the present study may reflect inter-population differences in mandibular morphology and the effects of genetic, environmental, and dietary factors.¹⁷ This variation highlights the importance of developing population-specific standards for forensic sex determination because the predictive accuracy can differ considerably across demographic groups.

According to widely accepted thresholds of predictive accuracy used in forensic anthropology and statistical model evaluation, which classify the accuracy as weak (<70 %), moderate (70–80 %), good (80–90 %), or excellent (>90 %), the present model falls within the moderate range.^24,25 This accuracy is slightly lower than that reported in studies based on multiple mandibular parameters, e.g., studies by Hanihara et al. (85 % accuracy in Japanese population), Giles et al. (84 % in Americans), Steyn et al. (81.5 % in White South Africans), and Renjith et al. (85.7 % in Malaysian Chinese), but it provides population-specific discriminant functions with practical utility in cases with limited remains.^17,26, 27, 28 Wankhede et al. also employed DFA to estimate sex based on various mandibular morphometric parameters.²⁹

The model developed in the present study provides moderate accuracy but it has several limitations. The overlap in mental foramen measurements between sexes and natural anatomical variability may reduce the discriminatory power. In addition, panoramic radiography can introduce imaging artifacts, and age-related changes or variations in dental status (e.g., missing teeth or alveolar resorption) may affect landmark identification and measurement precision. Finally, the derived discriminant function is population specific, limiting its applicability to other ethnic groups without further validation. A strength of the present study is its good sample size based on 3D radiographs.

Conclusion

In this study, significant sexual dimorphism was found in the position of the mental foramen among the Malay population. Significant sexual dimorphism was observed across all measurements (p < 0.001), where males had larger mean distances compared with females. The derived discriminant function achieved a classification accuracy of 75.18 %, where the left I–L had the highest discriminatory power (standardized coefficient = 0.488). Canonical correlation analysis (0.523) and Wilks' lambda (0.726) confirmed the model's robustness. The model is suitable for specimens with limited skeletal material, but it should be used together with other morphometric or skeletal parameters to improve the reliability. Our results highlight the importance of region- and population-specific standards, and provide a validated framework that can inform forensic anthropology practice and education. Future studies could analyze various bones from Malaysian populations or radiographs from other regions such as the skull to obtain more specific information.

Consent to participate

Consent was not required because this retrospective study was based on digital panoramic radiographs.

Consent to publish

Not applicable.

Ethical approval

The study was approved by the Institutional Ethical Committee of Manipal University College Malaysia (MUCM/Research and Ethics Committee – 006/2023).

Author contributions

Conceptualization: Dr Renjith George. Data Curation: Dr Sameer Kumar Vandrangi, Dr Harini Priya Ayanambakkam Hemasundar, Dr Preethy Mary Donald. Formal Analysis: Dr Venkata Bharathwaj Venkata Narasu. Funding Acquisition: Dr. Vikram Palimar. Investigation: Dr Sameer Kumar Vandrangi, Dr Harini Priya Ayanambakkam Hemasundar, Dr Preethy Mary Donald. Methodology: Dr Sameer Kumar Vandrangi, Dr Harini Priya Ayanambakkam Hemasundar, Dr Preethy Mary Donald. Project Administration: Dr Renjith George. Software: Dr Venkata Bharathwaj Venkata Narasu. Validation: Dr. Vikram Palimar. Visualization: Dr Renjith George. Original Draft Preparation: Dr Sameer Kumar Vandrangi, Dr Harini Priya Ayanambakkam Hemasundar, Dr Preethy Mary Donald. Review & Editing of the Manuscript: Dr. Vikram Palimar. We state that all authors have read and approved the final version of the article. All authors have critically reviewed and approved the final draft and are responsible for the content and similarity index of the manuscript.

Data availability

Data will be made available by the corresponding author on request.

Source of funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Conflict of interest

We declare that we have no conflicts of interest.