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 Table of Contents  
ORIGINAL ARTICLE
Year : 2016  |  Volume : 28  |  Issue : 1  |  Page : 7-10

Sex determination of human mandible using metrical parameters by computed tomography: A prospective radiographic short study


1 Department of Oral Medicine and Radiology, Hazaribag College of Dental Sciences, Hazaribag, Jharkhand, India
2 Department of Oral Medicine and Radiology, Rama Dental College, Kanpur, Uttar Pradesh, India
3 Department of Conservative Dentistry and Endodontics, M.R. Ambedkar Dental College, Bengaluru, Karnataka, India
4 Department of Oral Medicine, Buraydah College of Dentistry and Pharmacy, Buraydah, Saudi Arabia
5 Department of Oral Medicine and Radiology, Narsinhbhai Patel Dental College and Hospital, Visnagar, Gujarat, India

Date of Web Publication8-Sep-2016

Correspondence Address:
Kamala Rawson
Department of Oral Medicine and Radiology, Rama Dental College, Lakhanpur, Kalyanpur, Kanpur - 208 024, Uttar Pradesh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0972-1363.189990

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   Abstract 

Introduction: Sex determination of unidentified human remains is very important in forensic medicine, medicolegal cases, and forensic anthropology. The mandible is the largest and hardest facial bone that commonly resists postmortem damage and forms an important source of personal identification. Additional studies have demonstrated the applicability of facial reconstruction using three-dimensional computed tomography scan (3D-CT) for the purpose of individual identification. Aim: To determine the sex of human mandible using metrical parameters by CT. Materials and Methods: The study included thirty subjects (15 males and 15 females), with age group ranging between 10 and 60 years obtained from the outpatient department of Oral Medicine and Radiology, Narsinhbhai Patel Dental College and Hospital. CT scan was performed on all the subjects, and the data obtained were reconstructed for 3D viewing. After obtaining 3D-CT scan, a total of seven mandibular measurements, i.e., gonial angle (G-angle), ramus length (Ramus-L), minimum ramus breadth and gonion-gnathion length (G-G-L), bigonial breadth, bicondylar breadth (BIC-Br), and coronoid length (CO-L) were measured; collected data were analyzed using SPSS statistical analysis program by Student's t-test. Results: The result of the study showed that out of seven parameters, G-angle, Ramus-L, G-G-L, BIC-Br, and CO-L showed a significant statistical difference (P < 0.05), with overall accuracy of 86% for males and 82% for females. Conclusion: Personal identification using mandible by conventional methods has already been proved but with variable efficacies. Advanced imaging modalities can aid in personal identification with much higher accuracy than conventional methods.

Keywords: Mandible, sex determination, three-dimensional computed tomography


How to cite this article:
Kallalli BN, Rawson K, Ramaswamy VK, Zakarneh WH, Singh A, Zingade J. Sex determination of human mandible using metrical parameters by computed tomography: A prospective radiographic short study. J Indian Acad Oral Med Radiol 2016;28:7-10

How to cite this URL:
Kallalli BN, Rawson K, Ramaswamy VK, Zakarneh WH, Singh A, Zingade J. Sex determination of human mandible using metrical parameters by computed tomography: A prospective radiographic short study. J Indian Acad Oral Med Radiol [serial online] 2016 [cited 2019 Nov 20];28:7-10. Available from: http://www.jiaomr.in/text.asp?2016/28/1/7/189990


   Introduction Top


Human identification is the most challenging subjects that man has confronted. The determination of sex of the skeleton represents an important stage in the forensic anthropological investigation.[1],[2] The reliability of sex determination depends on the completeness of the remains and the degree of sexual dimorphism inherent in the population. When the entire adult skeleton is available for analysis, sex can be determined up to 100% accuracy; however, in cases of mass disasters where usually fragmented bones are found, sex determination with 100% accuracy is not possible and it depends largely on the available parts of the skeleton. As evident from the earlier studies, the skull is the most dimorphic and easily sexed portion of the skeleton after pelvis, providing accuracy up to 92%.[3],[4],[5] However, in cases where the intact skull is not found, mandible may play a vital role in sex determination as it is the most dimorphic, largest, and strongest bone of the skull.[6] The presence of a dense layer of compact bone makes it very durable and hence remains well preserved than many other bones.[7],[8],[9]

Conventional two-dimensional (2D) or three-dimensional (3D) computed tomography (CT) are useful imaging methods which can be used in the process of human identification and present innumerable advantages compared to traditional radiographic projections. These methods are free from the problem of structure superimposition beyond the plane of interest and also allow the visualization of small differences in density.[10],[11],[12] Anthropologically, CT has been utilized in the study of skulls and also in the forensic context as an additional resource in the process of identification. Additional studies have demonstrated the applicability of facial reconstruction using 3D-CT for the purpose of individual identification.[13] Associated with the advances in computer graphics, 3D reconstructed images from CT (3D-CT) have been used in several different clinical applications, as tumor measurements, dental implant planning, and evaluation of craniofacial deformities, and for anthropometric studies.[14] The aim of the study was to determine the sex of human adult using mandibular metrical parameters by 3D-CT.


   Materials and Methods Top


The study included thirty patients (15 males and 15 females) with the age range of 10–60 years from the Department of Oral Medicine and Radiology, Narsinhbhai Patel Dental College and Hospital, Visnagar. Ethical clearance was obtained. The purpose of the study was explained and informed consent was obtained from all the patients. A complete case history was taken; patients with any pathology and fracture of the mandible were excluded from the study. All the patients were subjected to the 3D-CT scan. Seven mandibular parameters were described according to Krogman and Iscan as follows:[15],[16]

  1. Gonial angle (G-angle): It is formed by the line tangent to the lower border of the mandible and the line tangent to the distal border of the ascending ramus and condyle [17]
  2. Ramus length (Ramus-L): Distance between the condylion and gonion
  3. Minimal ramus breadth (M-Ramus-Br): Smallest anterior–posterior diameter of ramus
  4. Coronoid height (CO-Ht): Projective distance between coronion and lower wall of bone
  5. Gonion-gnathion length (G–G-L): Mandibular base length
  6. Bicondylar breadth (BIC-Br): Distance between the condyle
  7. Bigonial length: Distance between the two gonions.


Five of them were measured from the lateral reconstruction CT image, and they are G-angle, Ramus-L, M-Ramus-Br, CO-Ht, and mandibular base length, i.e., G–G-L [Figure 1]. Other two parameters were measured from the axial reconstruction image, and they are bigonial breadth (BG-Br) and BIC-Br [Figure 2]. All the selected parameters were measured by Adobe Photoshop 7.0 software (Adobe Systems Inc., San Jose, California, United States) in a centimeter scale. All the measurements were performed by a single examiner to eliminate the interobserver bias. Collected data were analyzed using the SPSS statistical analysis program (IBM Corporation, New York, U.S.) by Student's t-test, and discriminant analysis with the stepwise feature was used to choose the most discriminatory variable.
Figure 1: Five mandibular parameters from lateral computed tomography reconstruction

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Figure 2: Two parameters from the axial reconstruction image

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   Results Top


Statistical analysis was done using Student's t-test and Chi-square test to determine the sex of the individual. Of seven parameters, five proved to be the best. G-angle (mean 114° for male and 120° for female); Ramus-L (mean 6.1 cm for male and 4.9 cm for female); G–G-L (mean 6.07 cm for male and 4.79 cm for female); BIC-Br (mean 9.9 cm for male and 8.75 cm for female); and coronoid length (CO-L) (mean 5.6 for male and 4.4 for female) showed statistically significant difference (P < 0.05) [Table 1]. Using stepwise discriminant analysis, accuracy was measured from the above five best parameters. It was found that the overall accuracy of this prediction model was 84%. It could correctly identify males in 86% and females in 82%. False identification occurred 14% in males versus 18% in females [Table 2].
Table 1: The mean value±standard deviation of the seven mandibular measurements compared between males and females using the student's t-test

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Table 2: Overall predictive accuracy (83.9%)

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   Discussion Top


Application of radiology in forensic sciences was introduced in 1896, just 1 year following the X-ray discovery by Sir Roentgen, to demonstrate the presence of lead bullets inside the head of a victim. Schuller, in 1921, proposed the possibility of utilizing radiological images of the facial sinuses for identification purposes.[10],[13] Hildelbolt and Vannier, in 1990, performed measurements on the conventional CT slices and on 3D reconstruction images, and compared the measurements with those performed with a caliper, and stated that 3D-CT measurements were more accurate than those taken from CT slices. Later, in 1998, Cavalcanti and Vannier validated linear craniofacial measurements in 2D-CT and 3D-CT images using a spiral CT and compared them with the corresponding physical measurements.[14]

Kharoshah et al. conducted a study for analysing the sexual dimorphism in mandible by 3D-CT in 2010[18] by taking the similar mandibular parameters in this study and concluded that BIC-Br, G-angle, and minimal Ramus-L have significant sexual dimorphism with overall accuracy of 83.9%; however, their study showed significant statistical difference with the G-angle, Ramus-L, G–G-L, BIC-Br, and CO-L (P < 0.05) with overall accuracy of 84%. Indira et al. in 2012[7] conducted a study on the mandibular ramus using panoramic imaging with similar parameters used in the present study in which 76% of overall accuracy in both males and females was seen; however, in the study by 3D-CT, accuracy seen was 86% for males and 82% for females. M-Ramus-Br measurement was found to be the best parameter in their study which was consistent with other osteometric studies by Giles (1964) and Vodanovic (2006), where breadth measurements were found to be very dimorphic. This is related to the differences in musculoskeletal development and the differences related to a different growth trajectory in males and females. In this study, M-Ramus-Br did not show a significant difference in sex determination.

Vinay in 2013[19] conducted a study on sex determination of human dry mandible using metrical parameters such as BG-Br, BIC-Br, and mandibular length and concluded that all these three parameters showed a significant gender difference. However, in the present study using 3D-CT, only BIC-Br and mandibular length showed significant gender difference. Saini et al.[20] conducted a study on dry adult mandibles in northern part of India and found that ramus expresses strong sexual dimorphism in this population. The overall prediction rate using five variables was 80.2%. The best parameters were CO-Ht, condylar height, and projective height of ramus, and breadth measurements were not very dimorphic in their sample. Similar results were found in this study with an overall accuracy of 86% for males and 82% for females.


   Conclusion Top


The mandible can be considered a valuable tool in gender determination since it possesses resistance to damage and disintegration processes. We found that the mandibular measurement using 3D-CT is reliable for the sex determination. With the availability of advanced imaging methods, forensic dentistry practitioner can successfully and accurately identify the sex of an unknown individual.

Acknowledgment

We thank STATSMASTER TEAM (statsmaster1@gmail.com) for their valuable statistical support for this research work.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
   References Top

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Rocha Sdos S, Ramos DL, Cavalcanti Mde G. Applicability of 3D-CT facial reconstruction for forensic individual identification. Pesqui Odontol Bras 2003;17:24-8.  Back to cited text no. 14
    
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Gamba TD, Alves MC, Neto FH. Mandibular sexual dimorphism analysis in CBCT scans of a Brazilian population. J Forensic Radiol Imaging 2014;2:104.  Back to cited text no. 15
    
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Kano T, Oritani S, Michiue T, Ishikawa T, Hishmat AM, Sogawa N, et al. Postmortem CT morphometry with a proposal of novel parameters for sex discrimination of the mandible using Japanese adult data. Leg Med (Tokyo) 2015;17:167-71.  Back to cited text no. 16
    
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Zangouei-Booshehri M, Aghili HA, Abasi M, Ezoddini-Ardakani F. Agreement between panoramic and lateral cephalometric radiographs for measuring the gonial angle. Iran J Radiol 2012;9:178-82.  Back to cited text no. 17
    
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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. 18
    
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Vinay G, Gowri SR, Anbalagan J. Sex determination of human mandible using metrical parameters. J Clin Diagn Res 2013;7:2671-3.  Back to cited text no. 19
    
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Saini V, Srivastava R, Rai RK, Shamal SN, Singh TB, Tripathi SK. Mandibular ramus: An indicator for sex in fragmentary mandible. J Forensic Sci, 2011;56:S13-6.  Back to cited text no. 20
    


    Figures

  [Figure 1], [Figure 2]
 
 
    Tables

  [Table 1], [Table 2]



 

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