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 Table of Contents  
ORIGINAL ARTICLE
Year : 2022  |  Volume : 34  |  Issue : 3  |  Page : 338-342

Significance of mandibular canal position and its foramina in cone beam computed tomography images of mandible for analysing sexual dimorphism- A retrospective study


Department of Oral Medicine and Radiology, Government Dental College and Hospital, Hyderabad, Telangana, India

Date of Submission04-Oct-2021
Date of Decision03-Mar-2022
Date of Acceptance12-Sep-2022
Date of Web Publication26-Sep-2022

Correspondence Address:
Sambhana Sailaja
Associate Professor, Department of Oral Medicine and Radiology, Government Dental College and Hospital, Hyderabad - 500 012, Telangana
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jiaomr.jiaomr_288_21

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   Abstract 


Background: Determination of gender from unidentified skeletal residue remains an arduous task in a forensic setting and for medico-legal assessment. The use of mandible in the field of human identification is less explored. Therefore, this study was done to analyze sexual dimorphism by identifying the relative location of mandibular canal and the mandibular and mental foramina using cone beam computed tomography images in a sample of south Indian inhabitants. Materials and Methods: This study was done on one hundred twenty cone beam computed tomography images (sixty males and sixty females) with an age range of twenty to sixty years. In these images, eight measurements were performed: six measurements in the coronal view and two measurements in the axial view. The variables between the sexes were compared using a student's t-test with level of significance of < 0.05. Results: All the eight variables were significant in predicting gender (P < 0.05). The mean values of all the measurements were higher in males except for one measurement which was higher in females. A logistic formula was obtained with all the variables to predict gender. Conclusion: The mandibular canal and the foramina showed significant differences among males and females of the study population. Therefore, the location of the mandibular canal and mental foramina can be used for gender determination in the study population.

Keywords: Forensic dentistry, gender determination, mandibular canal


How to cite this article:
Shil M, Sailaja S, Lavanya R, Ravali T, Fathima P R, Aparna T Y. Significance of mandibular canal position and its foramina in cone beam computed tomography images of mandible for analysing sexual dimorphism- A retrospective study. J Indian Acad Oral Med Radiol 2022;34:338-42

How to cite this URL:
Shil M, Sailaja S, Lavanya R, Ravali T, Fathima P R, Aparna T Y. Significance of mandibular canal position and its foramina in cone beam computed tomography images of mandible for analysing sexual dimorphism- A retrospective study. J Indian Acad Oral Med Radiol [serial online] 2022 [cited 2022 Nov 30];34:338-42. Available from: http://www.jiaomr.in/text.asp?2022/34/3/338/356959




   Introduction Top


Gender determination is crucial for personal identification and individual biological profile reconstruction, especially when the skeletal and fragmented remains are the only source of information as in many mass disasters and crime scenarios.[1],[2]

Studies have shown that skeletal measurements for gender differentiation are better in terms of reliability, and reproducibility than non-metric parameters.[3],[4] Mandibles have their own unique features and serve as exclusive identification tool. The mandibular canal exhibits variations in its anatomy and position between individuals of different genders.[5],[6] This unique characteristic of this anatomical landmark was the inspiration to investigate the correlation of its location and the gender of an individual in a sample consisting of inhabitants of south India. Oral and maxillofacial radiologists play a very important role in forensic sciences, and cone beam computed tomography (CBCT) is an advanced technique to overcome difficulties in personal identification.[7],[8]

With this background, we conducted a study with the main aim to evaluate sexual dimorphism through the location of the mandibular canal and the related mandibular and mental foramina using CBCT images and with the objective of measuring eight predictors in mandible and finding out their significance in gender determination.


   Materials and Methods Top


This is a retrospective cross-sectional study, performed in the Oral Medicine and Radiology department of the institution. One hundred and twenty cone beam computed tomography (CBCT) radiographs (60 of each gender) were selected randomly from the radiographic record of the patients who visited the Outpatient department and required CBCT radiographs for pre-orthodontic, wisdom teeth, and prosthodontic assessment. The study was approved by the institutional ethical board on August 26, 2020, with ethical clearance number IEC/OMC/M.NO.48 (Acad)/67 and agreed to the principles of the Helsinki Declaration.

Inclusion criteria

One hundred and twenty CBCT images with age ranging from 20 to 60 years without any trauma history in the head and neck region, and with caries free mandibular first molars, were included randomly in the study.

Exclusion criteria

Subjects below 20 years with history of fracture of the mandible, developmental defects or pathology, absence of mandibular first molar was excluded from the study.

Sample size estimation

Sample size was calculated from G power version 3.1.9.4 using t-test keeping significance level at 0.05 power at 80%. A total sample size estimated were 120 (60 of each gender).

Measurement parameters

A Corex 3D machine with exposure parameters of 70–80 Kvp, 5–10 mA, and 5cm × 10cm field of view was used, and storage of images were done in digital imaging and communications in medicine format. Software tool OnDemand3D was used to generate multiplanar reconstruction images on which topographic measurements were made. Eight predictors were measured in the study sample images obtained from CBCT. Two measurements AMaF (the length between the mandibular foramen and the anterior aspect of ramus) and PMaF (the length between the mandibular foramen and the posterior aspect of ramus) were performed on axial view in the region of the mandibular foramen [Graph 1]. Four measurements SIAC (the length between the superior aspect of the inferior alveolar nerve canal [IAC] and the occlusal aspect of the mandibular 1st molar), IIAC (the length between the inferior aspect of the inferior alveolar nerve canal [IAC] and the base of the mandible), LIAC (the length between the IAC and mandibular cortex lingually), BIAC (the length between the IAC and mandibular cortex buccally) were obtained from coronal view in the region of mandibular 1st molar [Graph 2] and [Graph 3]. Two measurements SMeF (the length between the mental foramen and the alveolar ridge crest) and IMeF (the length between the mental foramen and the base of the mandible) were done on the coronal view showing the mental foramen [Graph 4].



Reliability assessment

All the variables were measured again after 20 days by the same observer to check intra-observer variability and by a second observer to assess inter-observer variability and the level of agreement were assessed using intraclass correlation co-efficient with agreement levels: 0.00–0.36 disagreement; 0.37–0.52: mild; 0.53–0.68: moderate; 0.69–0.84: good; 0.85–1.00: excellent.

Statistical analysis

Statistical analysis was done with SPSS version 21. Descriptive analysis and student's t-test were performed for all predictors to know the significant predictors for gender determination [Table 1]. Linear discriminant function analysis was performed for all predictors. Wilk's lambda and F test were done to know which predictor can discriminate between genders [Table 2]. A canonical discriminant function coefficient for all the measurements and functions at group centroids i.e., average discriminant score was obtained for males and females [Table 3] and [Table 4].
Table 1: Gender wise comparison of study variables

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Table 2: Linear Discriminant functional analysis of the study variables

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Table 3: Canonical Discriminant Function Coefficients of study variables

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Table 4: Gender wise centroids

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   Results Top


All the eight predictors were significant in predicting gender (P < 0.05). The mean value of AMaF was higher in females. The mean values of PMaF, SIAC, IIAC, LIAC, BIAC, SMeF, and IMeF were higher in males. The highest difference was found in SIAC and the lowest in LIAC.

A discriminant function was obtained stepwise using the canonical discriminant function of 8 measurements with a determined constant. The group centroids were found as 2.554 for males and − 2.554 for females.

Discriminant function= [−10.17] − 0.62 (AMaF) +0 .744 (PMaF) + 0.221 (SIAC) +0.319

(IIAC) + 0.293 (LIAC) +0.093 (BIAC) −0.060 (SMeF) + 0.22 (IMeF)

The result of the equation closer to + 2.554, predicted the gender as male, and a value closer to − 2.554, predicted the gender as female.

An excellent level of intra-observer agreement and a good level of inter-observer agreement was observed, indicating that all the evaluated measurements are highly reliable and reproducible [Table 5] and [Table 6].
Table 5: Intra-observer reliability

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Table 6: Inter-observer reliability

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   Discussion Top


Forensic dentistry is of huge importance in forensic medicine for the recognition of dead victims as well as in relation to crimes and accidents. Gender determination is a branch of forensic dentistry, and it is the priority in human positive identification, hence a very important step.[9]

The mandible plays a crucial role in the identification of gender, possibly because it remains unblemished with a potency of sexual dimorphic attributes and because of the difference in the musculoskeletal development and growth trajectories of males and females. The mandibular canal exhibits variations in the anatomical position between individuals of different genders. This unique feature of the mandible has been used in the present study.[10],[11]

Previously, few similar studies were done on different populations, but limited studies were done on Indian population, with a smaller sample size. The present study was conducted on a sample consisting south Indian inhabitants with an increased sample size.

In present study, we observed that AMaF was greater in females compared to males, similar results were found in a study done by Oliveira Gamba et al. This could be attributed to differences in the anatomical features due to the control of sex hormones over bone growth. However, Mousa A et al. found that all measurements were higher in males. The differences between the study results could be because of the different ethnic origin of the study sample.[4],[5],[12],[13]

In our sample, PMaF, SIAC, and IIAC were greater in males compared to females. This was coinciding with the study done by M.H. Levine et al. This could be attributed to food, habits, and customs resulting in distinct anatomical features.[12],[13]

We observed SMeF, IMeF, LIAC, and BIAC were greater in the males compared to the females. The results were coinciding with a study done by Mousa A et al. This could be because of the greater strength of masticatory muscles in males. But the results contrasted with the study done by Vodanović et al.[14] on the Croatian population, where SMeF and IMeF were greater in females. The difference in results could be due to racial differences in the study populations. Thus, skeletal attributes differ by population, and therefore, there is a need for population-determined standards.[5],[15]

To correctly predict gender based on multiple predictors discriminant function analysis was used which showed all suitable predictors which can discriminate between genders. All eight measurements were used in the discriminant function as all of them were significant (P ≤ 0.05). Previously discriminant function analysis was used for gender identification in various studies cited below.[7],[8],[13],[14],[16]

Limitations and prospects

A multi-center study with similar parameters would give more accurate results. Also, we concentrated only on gender determination and did not consider age estimation. So, in future studies should be planned to evaluate the role of the mandibular canal in age estimation.


   Conclusion Top


With the advent of a new era, even the numbers of crimes are increasing and have become sophisticated, so we must adapt to new techniques in the identification of an individual. Here, all eight predictors were significant. Thus, the concerned anatomic landmarks can be considered for determining sexual dimorphism.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
   References Top

1.
Kharoshah MA, Almadani O, Ghaleb SS, Zaki MK, Fattah YA. Sexual dimorphism of the mandible in a modern Egyptian population. J Forensic Leg Med 2010;17:213-5.  Back to cited text no. 1
    
2.
O'Donnell C, Iino M, Mansharan K, Leditscke J, Woodford N. Contribution of postmortem multidetector CT scanning to identification of the deceased in a mass disaster: Experience gained from the 2009 Victorian bushfires. Forensic Sci Int 2011;205:15-28.  Back to cited text no. 2
    
3.
Gamba TO, Alves MC, Haiter-Neto F. Analysis of sexual dimorphism by locating the mandibular canal in images of cone-beam computed tomography. J Forensic Radiol Imaging 2014;2:72-6.  Back to cited text no. 3
    
4.
Gamba TO, Oliveira ML, Flores IL, Cruz AD, Almeida SM, Haiter-Neto F, et al. Influence of cone-beam computed tomography image artifacts on the determination of dental arch measurements. Angle Orthod 2014;84:274-8.  Back to cited text no. 4
    
5.
Mousa A, El Dessouky S, El Beshlawy D. Sex determination by radiographic localization of the inferior alveolar canal using cone-beam computed tomography in an Egyptian population. Imaging Sci Dent 2020;50:117-24.  Back to cited text no. 5
    
6.
Apinhasmit W, Methathrathip D, Chompoopong S, Sangvichien S. Mental foramen in Thais: An anatomical variation related to gender and side. Surg Radiol Anat 2006;28:529-33.  Back to cited text no. 6
    
7.
Anuthama K, Shankar S, Ilayaraja V, Kumar GS, Rajmohan M, Vignesh P. Determining dental sex dimorphism in South Indians using discriminant function analysis. Forensic Sci Int 2011;212:86-9.  Back to cited text no. 7
    
8.
Walker PL. Sexing skulls using discriminant function analysis of visually assessed traits. Am J Phys Anthropol 2008;136:39-50.  Back to cited text no. 8
    
9.
Kalistu SN, Doggalli DN. Gender determination by forensic odontologist: A review of various methods. J Dent Med Sci 2016;15:78-85.  Back to cited text no. 9
    
10.
Singal K, Sharma S. Age estimation by position of mental foramen in Haryana population: A radiographic study. J Adv Med Dent Scie Res 2017;5:68-73.  Back to cited text no. 10
    
11.
Von See C, Bormann KH, Schumann P, Goetz F, Gellrich NC, Rücker M. Forensic imaging of projectiles using cone-beam computed tomography. Forensic Sci Int 2009;190:38-41.  Back to cited text no. 11
    
12.
Levine MH, Goddard AL, Dodson TB. Inferior alveolar nerve canal position: A clinical and radiographic study. J Oral Maxillofac Surg 2007;65:470-4.  Back to cited text no. 12
    
13.
Naikmasur VG, Shrivastava R, Mutalik S. Determination of sex in South Indians and immigrant Tibetans from cephalometric analysis and discriminant functions. Forensic Sci Int 2010;197:122.e1-6.  Back to cited text no. 13
    
14.
Vodanović M, Dumančić J, Demo Ž, Mihelić D. Determination of sex by discriminant function analysis of mandibles from two croatian archaeological sites. Acta Stomatol Croat 2006;40:263-77.  Back to cited text no. 14
    
15.
Biwasaka H, Aoki Y, Tanijiri T, Sato K, Fujita S, Yoshioka K, Tomabechi M. Analyses of sexual dimorphism of contemporary Japanese using reconstructed three-dimensional CT images--curvature of the best-fit circle of the greater sciatic notch. Leg Med (Tokyo) 2009;11:260-2.  Back to cited text no. 15
    
16.
Prabhu S, Acharya AB. Odontometric sex assessment in Indians. Forensic Sci Int 2009;192:129.e1-5.  Back to cited text no. 16
    



 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]



 

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