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Table of Contents   
ORIGINAL RESEARCH  
Year : 2015  |  Volume : 26  |  Issue : 4  |  Page : 396-399
Mandibular canine index: A reliable predictor for gender identification using study cast in Indian population


1 Department of Oral Medicine and Radiology, Sri Aurobindo College of Dentistry, Indore, Madhya Pradesh, India
2 Department of Oral Medicine and Radiology, Darshan Dental College and Hospital, Loyara, Udaipur, Rajasthan, India
3 Department of Public Health Dentistry, Sri Aurobindo College of Dentistry, Indore, Madhya Pradesh, India
4 Oral Medicine and Radiology, Dafodyl Dental Clinic, Kolkata, West Bengal, India
5 Department of Prosthodontics, Hazaribag College of Dental Sciences, Hazaribag, Jharkhand, India

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Date of Submission30-May-2015
Date of Decision28-Jun-2015
Date of Acceptance11-Aug-2015
Date of Web Publication20-Oct-2015
 

   Abstract 

Context: Various methods are used for gender identification in anthropologic and forensic investigations. The canine tooth is widely used for gender determination because of its sexual dimorphism and durability in the oral cavity. Mandibular canine index (MCI) is one of the most reliable and valid predictor for gender identification. Aim: To assess the reliability of MCI in gender determination in Indian population. Settings and Design: This was an experimental study involving the preparation of plaster models of 100 individuals residing in Udaipur, Rajasthan, India. Of these 45 were males and 55 were females. Both sexes were in the age group of 20–30 years. Study casts were prepared for all individuals and the measurements of mandibular canine teeth were taken. The MCI was calculated using standardized equation. In addition, the percentage of sexual dimorphism was calculated. Statistical Analysis Used: Independent sample t-test was used. P < 0.05 was considered statistically significant. Results: There was a significant difference (P < 0.05) observed between inter-canine distance, right and left canine width and right and left MCI between males and females. Sexual dimorphism is more on left permanent mandibular canine teeth than right permanent mandibular canine teeth. The overall percentage of accuracy observed was 85.5%. Conclusions: Study findings reveal that MCI can be used a reliable predictor for gender determination in Indian population and can form the basis of anthropologic and forensic investigations.

Keywords: Canine, forensic dentistry, sex determination

How to cite this article:
Singh SK, Gupta A, Padmavathi B, Kumar S, Roy S, Kumar A. Mandibular canine index: A reliable predictor for gender identification using study cast in Indian population. Indian J Dent Res 2015;26:396-9

How to cite this URL:
Singh SK, Gupta A, Padmavathi B, Kumar S, Roy S, Kumar A. Mandibular canine index: A reliable predictor for gender identification using study cast in Indian population. Indian J Dent Res [serial online] 2015 [cited 2019 Aug 22];26:396-9. Available from: http://www.ijdr.in/text.asp?2015/26/4/396/167632


Mandibular canines exhibit the greatest sexual dimorphism among all teeth.[1] Sexual dimorphism refers to those differences in size, stature, and appearance between male and female that can be applied to dental identification as no two mouths are alike.[2]

In cases of mass disasters or major catastrophes, where the bodies are mutilated beyond recognition, the dimorphism in mandibular canines play a significant role in gender identification.[3] The only method that can give a totally accurate result is the DNA technique, but in many cases for several reasons it cannot be used. Teeth used in odontometric analysis, are an excellent material in living and nonliving populations for anthropological, genetic, odontologic, and forensic investigations. Their durability in the face of fire and bacterial decomposition makes them invaluable for identification.[1]

Many anatomical structures such as palatal rugae, lip prints have been studied for gender determination, although the teeth and their measurements seem to be one of the commonly employed method.[2] However, differences in tooth size, variations in root length and crown diameter, dental index, odontometric differences, Barr bodies, and using enamel protein have also been tried for sex determination.

Human teeth are the hardest and chemically the most stable tissues in the body, and are extremely durable even at higher temperatures. Teeth can be identified even when the rest of the body has undergone decomposition as in the case of using soft tissue structures for gender identification. They are therefore invaluable for identification on the fragmentary adult skeleton.[4],[5]

Sex determination using dental features is mainly based on the comparison of tooth dimensions in males and females.[2],[6] Mandibular canines are found to exhibit the greatest sexual dimorphism among all teeth because of the following reasons:

  • Canines are less exposed to plaque and calculus, so less severely affected by periodontal disease
  • Lesser pathological migration of mandibular canines than other teeth
  • Canines are the last teeth to be extracted with respect to age
  • Canines are more likely to survive in conditions such as air disasters, hurricanes, or conflagration.[1],[7],[8]


The present study establishes the impact of the “sex factor” on the morphometry of the mandibular canines. The dimorphism in maxillary canines can be of immense medico-legal use in gender identification. The study defines the morphometric criteria for mandibular canines in Udaipur population.


   Materials and Methods Top


This study was carried out on 100 individuals residing in Udaipur, Rajasthan. Of these 45 were males and 55 were females. Both sexes belong to age group between 20 and 30 years.

The inclusion criteria were patients having healthy periodontium, caries-free canine teeth and teeth having Class I canine relationship. Patients having carious or missing mandibular anterior teeth, the presence of abrasion, attrition, spacing, and crowding in mandibular anterior teeth and hard tissue diseases affecting the mandibular anterior teeth were excluded from the study.

Ethical approval to conduct the study was taken from the related institution. A pilot study was conducted on 10 study casts and based on the findings of the pilot study, keeping the power of the study to be 90%, it was decided to include a total of 100 participants in the final sample. PASS 13 software (NCSS Software, USA) was used to determine the final sample size. The measurements were carried out by two trained and calibrated dentists. A total of 10 study casts were measured and re-measured by the two dentists until the desired inter- and intra-examiner reliability was obtained (Cohen's Kappa value = 0.96).

Mandibular impressions of all the samples were made with alginate and study models were prepared with dental stone. Mandibular study models were used for the analysis. On the study model following measurements were taken. Mandibular canine width was measured as the greatest mesiodistal dimension of the mandibular canine on either side of the jaw using a digital vernier caliper [Figure 1].
Figure 1: Digital vernier caliper and study cast to measure the mandibular canine width

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For measuring the mesiodistal width of the canine, the vernier caliper was held parallel to the plane of occlusion [Figure 2].
Figure 2: Vernier caliper held parallel to the plane of occlusion, to measure the mesiodistal width of canine

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The intercanine distance was measured as the linear distance between the cusp tips of the right and left mandibular canine. The readings obtained from measurement of left and right mandibular canine width and intercanine distance were subjected to statistical analysis to assess the mandibular canine indices [Figure 3].
Figure 3: Measurement of inter canine distance using vernier caliper

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The formula used to determine canine index and sexual dimorphism were:

Observed mandibular canine index (MCIo) = mesiodistal crown width of mandibular canine/intercanine distance.[9]

Standard mandibular canine index (MCIs) = (mean male MCI − standard deviation [SD]) + (mean female MCI + SD)/2.[9]

Sexual dimorphism = (Xm/Xf) − 1 × 100[10]

Where, Xm = mean value of the male canine width

Xf = mean value for female canine width

Statistical analysis

The readings obtained were subjected to statistical analysis to assess sex difference using the unpaired t-test. Statistical analysis was done regarding intercanine distance, right canine width, left canine width, right mandibular canine index, left mandibular canine index (MCI), MCIo and MCIs, sexual dimorphism.


   Results Top


The study involved the preparation of 100 plaster casts from 45 males and 55 female participants. The intercanine distance was measured from the cusp tips of right and left mandibular canine using standardized criteria. The results showed that the mean value of the intercanine distance in males was 28.14 (4.06) mm with the coefficient of variation observed to be 0.66 which was significantly higher (t = 4.16, P < 0.001) than the mean value and coefficient of variation reported in females. In females, the mean value of the intercanine distance was found to be 25.70 mm with a coefficient of variation found to be 0.08.

The mean value of the width of right canine and left canine as measured using vernier calipers in males was found to be 7.19 mm and 7.32 mm with coefficient of variation to be 0.20 and 0.23, respectively and this was found to be significantly higher (P < 0.05) than those reported in females. The mean value of the width of right canine and left canine in females was found to be 6.30 mm and 6.35 mm respectively.

The MCI was calculated using a standardized formula. In males, the MCI on the right side was found to be 0.26 mm with a coefficient of variation of 0.15 whereas on the left side it was found to be 0.26 with a coefficient of variation of 0.18. In females, the MCI on the right side was found to be 0.25 mm whereas on the left side it was found to be 0.25 mm. The values of the calculated MCI were found to be significantly higher in males compared to females on both right and left sides.

Overall, the values obtained for the intercanine distance, right canine width, left canine width, right MCI, and left MCI was found to be significantly higher in males than females [Table 1].
Table 1: Mean and SD among inter-canine distance, right and left canine width and right and left mandibular canine index

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   Discussion Top


In the present study, there was a significant difference observed between the right canine width and left the canine width of males and females. Similar results were obtained in the previous studies done by Kaushal et al. and Reddy et al.[1],[11] The difference in width of canine between male and female teeth has been explained as part of the genetic expression of the male being larger than the female. It is the Y chromosome which intervenes most in the size of teeth by controlling the thickness of dentin, whereas the X chromosome responsible for the thickness of enamel. The sexual dimorphism in mandibular canines can be expected to be based on functional activity due to evolution and socialization.[12]

In the present study, there was a highly significant difference between the intercanine distance of males and females. The study findings also revealed that there was a significant difference between the right and left MCI among males and females. Similar findings were also reported in the studies done by Kaushal et al. and Patnaik et al.[1],[9] The contribution of various tissues in sexual dimorphism of tooth size was reported by Harris et al.[13] They found that males typically have significantly larger dentine and pulp dimensions than females; while marginal enamel thickness is similar in both sexes.[13] Moss and Moss-Salentijn suggested that dimorphism was related to an absolutely longer period of amelogenesis for both deciduous and permanent dentitions.[14]

Garn et al. concluded that the mandibular canine exhibited the greatest sexual dimorphism amongst all teeth (6.47% and 5.7%, respectively).[10] Nair et al. in their study done on South Indian subjects reported that the left mandibular canine exhibited a sexual dimorphism of 7.7% and the right mandibular canine 6.2%.[15] In the present study also, the left mandibular canine was found to exhibit greater sexual dimorphism (15.2%), as compared to the right mandibular canine (14.1%). Thus, usage of left mandibular canine, to estimate the gender of the individual will give more precise results.

In the present study, the percentage of accuracy obtained by comparing MCIo with MCIs using both right and left sides was 83.8% in males and 87.2% in females. The overall percentage of accuracy was 85.5%. The study finding was close to the percentage of accuracy obtained by Nair et al., in their study done in South Indian population, where in they found the accuracy to be 84.3% in males and 87.5% in females.[15]


   Conclusion Top


The significant results obtained on comparison of right and left mandibular canine indices in males and females justify its usage as a tool for the determination of sex of an individual. The findings indicate that the dimorphism in mandibular canines can be of immense medico-legal use in gender identification. Gender of an individual cannot be estimated if the fragment of the mandible is from the different geographical area unless random sampling of the population of that area has been done to calculate the corresponding MCIs. However, it is not a confirmatory test and is done as an adjunct with other tests for gender identification.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
   References Top

1.
Kaushal S, Patnaik VV, Agnihotri G. Mandibular canines in sex determination. J Anat Soc India 2003;52:119-24.  Back to cited text no. 1
    
2.
Parekh DH, Patel SV, Zalawadia AZ. Odontometric study of maxillary canine teeth to establish sexual dimorphism in Gujarat population. Int J Biol Med Res 2012;3:1935-7.  Back to cited text no. 2
    
3.
Singh J, Gupta KD, Sardana V, Balappanavar AY, Malhotra G. Sex determination using cheiloscopy and mandibular canine index as a tool in forensic dentistry. J Forensic Dent Sci 2012;4:70-4.  Back to cited text no. 3
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4.
Kapila R, Nagesh KS, R Iyengar A, Mehkri S. Sexual dimorphism in human mandibular canines: A radiomorphometric study in South Indian population. J Dent Res Dent Clin Dent Prospects 2011;5:51-4.  Back to cited text no. 4
    
5.
Muller M, Lupi-Pegurier L, Quatrehomme G, Bolla M. Odontometrical method useful in determining gender and dental alignment. Forensic Sci Int 2001;121:194-7.  Back to cited text no. 5
    
6.
Vodanovic M, Demo Z, Njemirovskij V, Keros J, Brkic H. Odontometrics: A useful method for sex determination in an archaeological skeletal population. J Arch Sci 2007;34:905-13.  Back to cited text no. 6
    
7.
Ibeachu PC, Didia BC, Orish CN. Sexual dimorphism in mandibular canine width and intercanine distance of university of port-harcourt student, Nigeria. Asian J Med Sci 2012;2:166-9.  Back to cited text no. 7
    
8.
Vishwakarma N, Guha R. A study of sexual dimorphism in permanent mandibular canines and its implications in forensic investigations. Nepal Med Coll J 2011;13:96-9.  Back to cited text no. 8
    
9.
Patnaik VV, Kaushal S, Sood V, Agnihotri G. Sex determination in North Indians using mandibular canine index. JIAFM 2004;26:45-9.  Back to cited text no. 9
    
10.
Garn SM, Lewis AB, Kerewsky RS. Buccolingual size asymmetry and its developmental meaning. Angle Orthod 1967;37:186-93.  Back to cited text no. 10
    
11.
Reddy VM, Saxena S, Bansal P. Mandibular canine index as a sex determinant: A study on the population of western Uttar Pradesh. JOMFP 2008;12:56-9.  Back to cited text no. 11
    
12.
Narang RS, Manchanda AS, Malhotra R, Bhatia HS. Sex determination by mandibular canine index and molar odontometrics: A comparative study. Indian J Oral Sci 2014;5:16-20.  Back to cited text no. 12
  Medknow Journal  
13.
Harris EF, Hicks JD, Barcroft BD. Tissue contributions to sex and race: Differences in tooth crown size of deciduous molars. Am J Phys Anthropol 2001;115:223-37.  Back to cited text no. 13
    
14.
Moss ML, Moss-Salentijn L. Analysis of developmental processes possibly related to human dental sexual dimorphism in permanent and deciduous canines. Am J Phys Anthropol 1977;46:407-13.  Back to cited text no. 14
    
15.
Nair P, Rao BB, Annigeri RG. A study of tooth size, symmetry and sexual dimorphism. J Forensic Med Toxicol 1999;16:10-3.  Back to cited text no. 15
    

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Correspondence Address:
Siddharth Kumar Singh
Department of Oral Medicine and Radiology, Sri Aurobindo College of Dentistry, Indore, Madhya Pradesh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0970-9290.167632

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