|FORENSIC ODONTOLOGY: ORIGINAL ARTICLE
|Year : 2019 | Volume
| Issue : 3 | Page : 246-251
Gender determination using mandibular canine index in general population
Rakhee R Modak, Amit A Mhapuskar, Darshan Hiremutt, Santosh Jadhav, Manjula Hebbale, Harshal Varpe
Department of Oral Medicine and Radiology, Bharati Vidyapeeth Deemed to be University Dental College and Hospital, Pune, Maharashtra, India
|Date of Submission||04-Apr-2019|
|Date of Acceptance||01-Aug-2019|
|Date of Web Publication||30-Sep-2019|
Dr. Rakhee R Modak
701-A, Concord Portia, Balewadi, Pune - 411 045, Maharashtra
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Context: Gender determination of skeletal remains is part of archeological and medicolegal examination. In forensic investigations mandibular canines provide excellent material to identify gender as they are more likely to survive in disaster. Dimorphism in mandibular canines is of immense use in forensic investigation. Aim: The aim of study was to establish mandibular canine index (MCI) for gender determination in general population for age group of 18--30 years and to find out efficiency of MCI in establishing gender identity of individual. Setting and Study Design: Patients reporting to Department Of Oral Medicine and Radiology are selected for study after applying inclusion and exclusion criteria. Materials and Methods: The study was conducted on 200 subjects in general population; (100 males and 100 females). Following parameters were considered in study; mesiodistal width of right and left mandibular canine, intercanine arch width and right and left MCI. All measurements were taken intraorally and then on dental casts of same individuals followed by MCI calculation. Statistical Analysis Used: In the entire study the P –value less than 0.05 was considered to be statistically significant. The entire data were statistically analyzed by using (SPSS ver 16, IBM corporation, USA). Results: Using the MCI value, gender can be correctly predicted up to 81% in females and 85% in males. Overall, percentage accuracy of MCI in prediction of gender was 83%. The standard MCI value was 0.2661. Also, right canine was found to exhibit more dimorphism than left canine. Conclusion: It was evident from this study that MCI is a good tool for determining gender. It is quick, reliable, and inexpensive method. Along with other parameters it increases percentage accuracy of predicting gender.
Keywords: Dimorphism, intercanine distance, mesiodistal width, mandibular canine index
|How to cite this article:|
Modak RR, Mhapuskar AA, Hiremutt D, Jadhav S, Hebbale M, Varpe H. Gender determination using mandibular canine index in general population. J Indian Acad Oral Med Radiol 2019;31:246-51
|How to cite this URL:|
Modak RR, Mhapuskar AA, Hiremutt D, Jadhav S, Hebbale M, Varpe H. Gender determination using mandibular canine index in general population. J Indian Acad Oral Med Radiol [serial online] 2019 [cited 2019 Oct 14];31:246-51. Available from: http://www.jiaomr.in/text.asp?2019/31/3/246/268279
| Introduction|| |
The basis of individuality of the person is identification through the uncharacteristic features. Gender determination of skeletal remains is a part of archaeological and medicolegal examination. In cases where teeth alone found on site with complete destruction of jaw bones, skull and long bones, gender determination still can be done. The human teeth due to its extreme hardness value and high resistance against decomposition are selected for postpartum investigations where other body parts cannot be used due to decomposition and mutilation.
Canines are known as “corner stone teeth” due to size and highest survival rate. Mandibular canines have mean age of eruption of 10.87 years. They are rarely extracted as they have decreased incidence of caries, abrasion, and heavy occlusal loading. They are rarely affected by periodontal pathology. Also, they survive in trauma such as air disaster, hurricanes, and conflagration. These findings indicate that canines are considered as “Key Teeth” for gender determination. The present study was aimed to establish the difference in mesiodistal dimensions between both permanent mandibular canines and classify all the subjects under study into males and females based on values of mandibular canine indices obtained.
To assess efficacy of mandibular canine index (MCI) in determining gender of individual by measuring mesiodistal width of mandibular canines and intercanine arch width.
- To establish gender identity through MCI.
- To investigate which mandibular canine exhibits greater sexual dimorphism.
| Materials and Methods|| |
The study was initiated after the protocol had been approved by institutional research and ethical committee. The study was performed among apparently healthy individuals reporting to Department of Oral Medicine and Radiology. The procedure was explained to subjects and written informed consent was obtained from subjects. The study sample comprised of 200 subjects; 100 males and 100 females patients in age group of 18--30 years. This age group was selected since root completion of mandibular canines occurs at age of 13--15 years; canines would have completely erupted by this age and attrition is minimum. The subjects were selected on basis of following inclusion and exclusion criteria.
- Subjects in age group 17--30 years.
- Fully erupted, noncarious mandibular canines.
- Healthy state of gingiva and periodontium.
- Dental abnormalities, rotation, occlusal disharmony.
- Physiologic and pathologic wear and tear (attrition, abrasion, abfraction, and erosion)
- Partially erupted, ectopically placed canines.
- No previous or current orthodontic treatment.
| Method|| |
The study design was double-blinded study. The subjects were numbered serially as they entered study. Then participant's intraoral measurements were taken. Mesiodistal width and intercanine distance were recorded between divider points [Figure 1] and [Figure 2]. Divider was held against vernier caliper and readings were noted [Figure 3].
|Figure 1: Measurement of mesiodistal width of the left mandibular canine clinically|
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|Figure 2: Measurement of intercanine distance between cusps tips of right and left canine clinically|
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|Figure 3: Transfer of measurements between divider points on vernier caliper|
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Following intraoral measurements, mandibular impressions were obtained using alginate impression material and stainless steel perforated trays. Impressions were immediately poured in type III dental stone to avoid dimensional changes. The impressions were separated from casts after 40 minutes and retrieved casts were dipped in 2% gluteraldehyde for disinfection. The bases were poured using orthodontic base former. The measurements were done on study model placed on suitable base using divider and digital vernier valiper (ABSOLUTE DIGIMATIC) with least count of 0.001 mm.
Mesiodistal dimension of both mandibular canines in individual cast was measured with a divider. Divider was positioned perpendicular to long axis of tooth, against most convex point (i.e. height of contour) on mesial and distal aspect of canine on cast. Thus, mesiodistal width of right and left canine was measured [Figure 4]. The intercanine distance was measured as a linear distance between cusp tip of right and left mandibular canine using divider positioned perpendicular to long axis of tooth. Divider was held against vernier caliper and reading was noted. The above measurements were taken on 200 casts. Each parameter of the study was measured separately and independently by two skilled investigators and its average was obtained to minimize intraobserver error. The average was obtained for intraoral measurements and measurements on cast for all parameters. The data collected were recorded in proforma and analyzed statistically.
|Figure 4: Measurement of mesiodistal width of left canine on dental cast using divider|
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MCI was calculated for each subject using formula given by Rao et al. as follows,
The mean values for male MCI and female MCI were calculated. After this standard MCI value was obtained by using following formula.
The observed MCI value MCIO was then compared with standard MCIS obtained.
Thus, standard MCI value was used as a cutoff point to differentiate males from females.
If MCIO for subject is higher than MCIS then individual was considered as male and vice -a –versa.
Accuracy was calculated as area under curve by using Receiver Operating Characteristic curve ROC curve, Kappa coefficient for diagnostic accuracy with male and female for cut off value. This was done by statistical analysis.
Sexual dimorphism- It refers to those differences in size, stature, and appearances between male and female that can be applied to dental identification.
Sexual dimorphism in right and left mandibular canines was calculated by applying formula given by Garn and Lens in 1967
Xm R = mean value of males right canine width.
Xf R = Mean value of females right canine width.
Similarly, sexual dimorphism for left canine was measured. Thus, percentage analysis of sexual dimorphism revealed that which mandibular canine exhibit greater sexual dimorphism.
| Results|| |
In the entire study the P –value less than 0.05 was considered to be statistically significant. The entire data were statistically analyzed by using (SPSS ver 16, IBM corporation, USA).
Standard MCI value was 0.2661; values above this were considered as males and below this as females. The mean right canine width was significantly higher in male 7.61 mm compared to female 6.75 mm. P value < 0.001. Also the mean left canine width was higher in males 7.59 mm compared to females 6.75 mm. P value < 0.001 [Table 1], [Graph 1]. Mean intercanine distance was 27.38 mm in males and 26.12 mm in females, with P value highly significant. [Table 2], [Graph 2].
Also, distribution of mean right and left canine index was significantly higher in males. [Table 3], [Graph 3]. The percentage accuracy for males was 81% and for females 85%. [Table 4]. Overall, percentage accuracy of MCI in prediction of gender was 83%. The sexual dimorphism for right mandibular canine was 12.74% and for left was 12.44. [Table 5].
|Table 3: Statistical significant mandibular canine index between male and female subjects|
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|Table 4: Percentage accuracy of gender establishment by mandibular canine index method|
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Statistical significance of above parameters, i.e mean width of canine, mean intercanine width and mandibular canine index in male and female subjects is summerized in [Table 6].
| Discussion|| |
One of the major roles of forensics in human identification is establishment of gender of individuals. Various methods are used for gender identification. Many anatomical structures such as palatal rugae, lip prints have been studied for this. But odontometric analysis is most steadfast method.
In present study, there was significant difference observed between right and left canine width of males and females [Graph 1]. Similar results were obtained in previous studies done by Kaushal et al. (2004) and Reddy et al., (2008). The difference in width of canine between male and female teeth is attributed to Y chromosome that controls thickness of dentin, whereas X chromosome is responsible for thickness of enamel. The studies conducted by Ghose and Baghdady et al. (1979) on Iraqi population, Lysell and Myrberg  (1982), on Swedish population and by Bishara et al. (1989), on population of Egypt, Mexico showed consistent findings. Studies done by Acharya and Mainali et al. (2007) revealed a reverse dimorphism. Nepalese population and canine width were larger in females than males and this could be attributed to evolutionary process resulting in a reduction in sexual dimorphism.
In present study intercanine width was found greater in males than females [Graph 2]. Our results are consistent with similar study carried by Bindu et al. (2008) and Kumar et al. (1989). Gudipudi Shreedhar et al. (2015), in similar study in 60 individuals among Moradabad population reported intercanine width significantly higher in males than females. In present study Mean MCI in male was 0.278 and Mean MCI for female was 0.259. P value < 0.001. Therefore, in our study MCI in males was higher than females [Graph 3]. Similar findings were reported in studies done by Vishwakarma and Guha et al. (2011). In another study by Jitendra Acharya, Garg et al. (2015) on 80 subjects in age group of 17--30 years from Rajasthan population found highly significant results for all parameters, i.e. canine width, intercanine width and MCI; values being higher for males.
In present study, percentage accuracy obtained was 81% for males and 85% for females, whereas overall accuracy was 83%. Our study findings were close to accuracy obtained by Rao et al., they found accuracy to be 84.3% in males and 87.5% in females. Our study results are also in close accordance with study conducted by Yadav et al. (2002); males 83.3% of cases and females were identified in 81% of cases. Singh et al. (2015) found accuracy to be 83.3% in males and 87.2% in females. The sensitivity and specificity of prediction of gender by MCI was 84.38% and 81.73%, respectively. In present study, a higher sexual dimorphism was found in right canine 12.74% than left 12.44% which is in accordance with study conducted by Vishwakarma and Guha  (2011). In another study conducted by Kiran et al. (2014) higher sexual dimorphism was found for right canine than left. This difference can be attributed to several factors, such as racial, environmental, cultural, and nutritional factors. There can be complex interaction between genetic and environmental factors.,
Thus, it is evident from this study that mandibular canine revealed greatest sexual dimorphism with significant width in males than in females. Also intercanine distance was greater in males than females; with right mandibular canine to be more dimorphic than left canine.
| Conclusion|| |
The significant results were obtained on comparison of right and left mandibular canine indices in males and females. It can be concluded from present study that standard MCI is a quick and easy method for gender determination and in identification of an unknown individual. In our study gender could be predicated to an extent of about 83% in general population. Present study also establishes statistically significant sexual dimorphism, the right mandibular canine was more dimorphic than left. This can be of immense medicolegal use and can be used in large population. However, MCI can be used as supplemental tool, with other parameters as accuracy of MCI in identification of gender never exceeded 87.5%. It is recommended in future to conduct similar studies on various populations taking larger sample size.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient (s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]