Use of mandibular canine index as a tool in gender dimorphism: A phenotypic study

Taseer Bashir; Srinivas Kandakurti; Jyoti Gupta; Arti S Sachdeva; Naeem Ahmad; Vijay Krishnan

doi:10.4103/0972-1363.200633

ORIGINAL ARTICLE

Year : 2016 | Volume : 28 | Issue : 4 | Page : 386-390

Use of mandibular canine index as a tool in gender dimorphism: A phenotypic study

Taseer Bashir¹, Srinivas Kandakurti¹, Jyoti Gupta¹, Arti S Sachdeva¹, Naeem Ahmad², Vijay Krishnan¹
¹ Department of Oral Medicine Diagnosis and Radiology, Career Post-Graduate Institute of Dental Sciences, Lucknow, Uttar Pradesh, India
² Department of Prosthodontics, Career Post-Graduate Institute of Dental Sciences, Lucknow, Uttar Pradesh, India

Date of Submission	23-Nov-2015
Date of Acceptance	23-Dec-2016
Date of Web Publication	21-Feb-2017

Correspondence Address:
Dr. Taseer Bashir
Department of Oral Medicine Diagnosis and Radiology, Career Post-Graduate Institute of Dental Sciences, Lucknow, Uttar Pradesh
India

Source of Support: None, Conflict of Interest: None

Check

DOI: 10.4103/0972-1363.200633

Abstract

Introduction: The role of human dentition in gender dimorphism can be investigated owing to its resistance against peri and postmortem insults. Hence, it forms an excellent tool for forensic, genetic, odontological and anthropological investigations. Among all the teeth, the mandibular canines are found to exhibit the greatest gender dimorphism. Aim: To determine a method of diagnosing gender from the dentition in a population of Ghailla village, Lucknow, Uttar Pradesh, India. Materials and Methods: Intercanine distance and widths of both right and left mandibular canine were measured intraorally and on the dental casts of the same individuals followed by mandibular canine index calculation. Results: In the female group, the mesiodistal (MD) width was less than 7 mm in the majority of individuals. It was also interpreted that the left canine was found to exhibit greater gender dimorphism. The reliability with regards to gender was 76.6% for males and 73.3% for females. The standard value of mandibular canine index was (0.35); hence, numerical quantities above this value belonged to the masculine sex and below this value belonged to the feminine sex. Conclusion: The left canine was found to exhibit greater gender dimorphism. Whenever the width of either canine was greater than 7 mm, the probability of gender being male was 100% in the present study.

Keywords: Canine index, canine width, intercanine distance, mandibular canines

How to cite this article:
Bashir T, Kandakurti S, Gupta J, Sachdeva AS, Ahmad N, Krishnan V. Use of mandibular canine index as a tool in gender dimorphism: A phenotypic study. J Indian Acad Oral Med Radiol 2016;28:386-90

How to cite this URL:
Bashir T, Kandakurti S, Gupta J, Sachdeva AS, Ahmad N, Krishnan V. Use of mandibular canine index as a tool in gender dimorphism: A phenotypic study. J Indian Acad Oral Med Radiol [serial online] 2016 [cited 2021 Jan 28];28:386-90. Available from: https://www.jiaomr.in/text.asp?2016/28/4/386/200633

Introduction

Gender dimorphism refers to the differences in the size and form between males and females that can be applied for dental identification. These differences can be applied as no two mouths are similar.^[1] Gender determination is the first and foremost task in any kind of forensic investigation of unidentified bodies and skeletal remains. As the total human population is more or less equally divided among both the genders, it also reduces the search of individuals to half.It is a known fact that enamel is the hardest known substance in the human body. Teeth are made of enamel and hence are supposed to bear any kind of trauma. The human teeth owing to its extreme hardness value and high level of resistance against any kind of decomposition are selected for postmortem investigations. It has been reported in previous studies that human teeth possess some kind of dimorphic variations.^[2] Hence, this feature must be explored further because it may be used for gender determination in adjunct with odontometric analysis.^[3]

Canines are known as “cornerstone teeth” due to their size and the highest survival rate. It has a mean eruptive age of 10.87 years. Canines are the least encountered teeth for extraction as well as the least involved tooth by periodontal disease. Hence, for gender identification, mandibular canines are selected among all the teeth.^[4]

Aim

To measure the gender dimorphism using mandibular canine index in a Ghailla population.

Objectives

To measure the mesiodistal (MD) crown width of mandibular canine
To measure the mandibular canine arch width or intercanine (IC) distance
To determine a method for diagnosing gender from the dentition in a population of Ghailla village, Lucknow, Uttar Pradesh, India.

Materials and Methods

This study was performed among apparently healthy individuals reporting to the Department of Oral Medicine Diagnosis and Radiology (OMDR) wing in the Career Post-Graduate Institute of Dental Sciences (CPGIDS), Lucknow. The samples consisted of mandibular dental arches from 60 patients consisting of 30 males and 30 females, aged between 20 and 30 years. This age group was selected because attrition is minimal in this age group. Selection criteria included a complete set of fully erupted healthy teeth.^[5]

After obtaining a written informed consent, the impressions of the teeth were made using plastic trays ^[6] and irreversible hydrocolloid impression material and were immediately poured in type-III dental stone [Figure 1]. MD dimensions ^[7] of both the mandibular canines in the individual/cast were measured with a divider ^[8] which was positioned perpendicularly along the long axis of the selected tooth or coinciding with it [Figure 2] and [Figure 3]. The IC distance was measured between the cusp tips of mandibular canines using a divider positioned perpendicular to the long axis of the teeth [Figure 4].

Figure 1: Mandibular casts: female sample and male sample

Click here to view

Figure 2: Measurement of the left mandibular canine mesiodistal width in the participant

Click here to view

Figure 3: Measurement of the left mandibular canine mesiodistal width in the cast

Click here to view

Figure 4: Measurement of the intercanine width in the participant

Click here to view

Percentage of dimorphism

It is defined as “the percentage by which the tooth size of male gender exceeds that of the female gender.”^[9] All the observations and calculations were done by a single investigator to eliminate the incidence of interobserver error. Each reading was also recorded three times, and its average was obtained to minimize intraobserver error. The data collected was statistically analyzed.

Mandibular canine index

Ratio of MD crown width of mandibular canine to mandibular canine arch width or IC distance using the formula given by Rao et al.(1989) was measured.^[10]

Gender dimorphism

Gender dimorphism in the right and left mandibular canines was calculated using the formula given by Garn and Lens (1967):^[11]

Percentage of gender dimorphism = (Xm/Xf) −1 × 100

Xm = Mean value of males

Xf = Mean value for females

The sample was evaluated using the Statistical Package for the Social Sciences version 8.3.3 software (SPSS Inc., Chicago, IL, USA). It was inferred that a definite statistically significant gender dimorphism existed in mandibular canines within Ghailla village population.

Selection of participants

After consulting our statistician, the sample size was calculated with 1% of the total population reporting to the dental clinic in a year, which is approximately 250 patients per month. This implies that 30 individuals [1% of 3000 individuals (250 × 12)] are sufficient to make calculations regarding gender dimorphism in this population to have a good power of analysis.

Sampling method

A purposive sample of 30 individuals in each group presenting to this dental college cum tertiary care hospital was selected for this study.

Results

The statistical analysis showed that 23 males (out of 30) and 22 females (out of 30) were correctly classified (success rate of 74.9%). [Table 1] shows the statistical significance of different parameters. [Table 2] shows that, in the female group, MD width was less than 7 mm in a majority of participants. [Table 3] shows that the left canine exhibited greater gender dimorphism whether measurements were made intraorally or on casts. The reliability with regards to gender was 76.6% for males and 73.3% for females. Standard value of mandibular canine index was (0.35) numerical quantities; values above this belonged to the masculine sex and below this belonged to the feminine sex.

Table 1: Statistical significance of different parameters

Click here to view

Table 2: Range of canine width in different groups of males versus females

Click here to view

Table 3: Gender dimorphism in mandibular canines

Click here to view

Discussion

Studies on tooth morphology have been conducted in the past using either intraoral measurements or measurements on casts.^[5] Barrett et al.^[12] observed that the reliability of intraoral measurements were less. Garn and Lewis,^[5] and Lysell and Myrberg ^[13] found that the mandibular canines exhibited the greatest gender dimorphism among all the teeth. The mean eruptive age of mandibular canines is approximately 10.87 years. It is already reported that canines are the least affected teeth by the periodontal disease compared to others. These are also the last remaining teeth in the oral cavity. Because enamel is the hardest known part of human body and canines possess the maximum amount of it, they are the most resistive to any kind of trauma.^[4] In the present study, participants in the age group of 20–30 years were included, as early adulthood dentition has less mutilation and less attrition, which is in agreement with the findings of Doris et al.^[14] Nair et al.^[15] concluded that the left mandibular canine revealed maximum sexual dimorphism (7.7%), followed by the right mandibular canine (6.2%). Similarly, Kaushal et al.^[5] also found left mandibular canine (9.26% in casts and 8.89% intraorally) to be more dimorphic than the right mandibular canine (7.45% in casts and 7.44% intraorally). In the present study, similar findings were obtained but with a higher value (9.79% for the left mandibular canine, followed by the right mandibular canine with 7.96%).

However, in 1993, Hashim and Murshid ^[16] found that there was no significant difference between the left and right mandibular canines in a Saudi population sample. On the contrary, Vishwakarma and Guha ^[17] found that the right mandibular canine (12.51%) was more dimorphic than the left mandibular canine (10.15%). Hence, this difference can be attributed to several factors such as racial, environmental, cultural and nutritional factors. Variation in food source is a known environmental factor that causes morphological alterations in tooth.^[18] Hence, this area of research demands further investigation and emphasizes on the need for population-specific data.

Conclusion

Despite certain limitations of the study, it was concluded that the left canine exhibited greater gender dimorphism. Whenever the width of either canine was greater than 7 mm, probability of the gender being male was 100% in the present study. This finding has great medicolegal significance, especially for identification of gender. Odontometric parameters can be used for determining gender in a large population because they are simple, inexpensive and easy to measure. However, it should always be contemplated as an appendage rather than as a primary option.

Acknowledgment

The authors acknowledge the Department of Prosthodontics, Career Post-Graduate Institute of Dental Sciences, Lucknow, Uttar Pradesh, India, for the help rendered in conducting this study.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

References

1.	Fouad A, Loubna S, Mohamad R, Antoine C, Randa D, Ibrahim Z, et al. Mandibular canine dimorphism in establishing sex identity in the Lebanese population. Int J Dent 2014;52:1-4.
2.	Dahlberg AA. Dental traits as identification tools. Dent Prog 1963;3:155-60.
3.	Gadiputi S, Masineni NS, Gayathri R, Ramesh N, Aditi M, Ashutosh A. Dimorphic mandibular canines in gender determination in Moradabad population of Western Uttar Pradesh. J Forensic Dent Sci 2015;7:32-6.
4.	Dahlberg AA. Forensic dentistry. J Am Dent Assoc 1976;93:991-5.
5.	Kaushal S, Patnaik VG, Agnihotri G. Mandibular canines in sex determination. J Anat Soc India 2003;52:119-24.
6.	Faiez NH. Mesiodistal crown diameters and tooth size discrepancy of permanent dentition in thalassemic patients. J Clin Exp Dent 2013;5:239-44.
7.	Hashim HA, Murshid ZA. Mesiodistal tooth width. A comparison between Saudi males and females. Part 1. Egypt Dent J 1993;39:343-6.
8.	Parekh DH, Patel SV, Zalawadia AZ, Patel SM. Odontometric study of maxillary canine teeth to establish sexual dimorphism in Gujarat population. Int J Biol Med Res 2012;3:1935-7.
9.	Jonathan W. Sexual dimorphism in body composition across human populations: Associations with climate and proxies for short- and long-term energy supply. Childhood Nutrition Research Centre, UCL Institute of Child Health, London. Am J Hum Biol 2012;24:411-9.
10.	Rao NG, Rao NN, Pai ML, Kotian MS. Mandibular canine index- A clue for establishing sex identity. Forensic Sci Int 1989;42:249-54.
11.	Garn SM, Lewis AB, Kerewsky RS. Buccolingual size asymmetry and its developmental meaning. Angle Orthod 1967;37:186-93.
12.	Barrett MJ, Brown T, Macdonald MR. Tooth size in Australian aborigines. Aust Dent J 1963;8:150-5.
13.	Lysell L, Myrberg N. Mesiodistal tooth size in the deciduous and permanent dentitions. Eur J Orthod 1982;4:113-22.
14.	Doris JM, Bernard BW, Kuftinec MM, Stom D. A biometric study of tooth size and dental crowding. Am J Orthod 1981;79:326-36.
15.	Nair P, Rao BB, Annigeri RG. A study of tooth size, symmetry and sexual dimorphism. J Forensic Med Toxicol 1999;16:10-3.
16.	Hashim MA, Murshid ZA. Mesiodistal tooth width in a Saudi population sample comparing right and left side: Part 2. Egypt Dent J 1993;39:347-50
17.	Halim A. Regional and clinical anatomy for dental students. In: General Principles of Anthropology. 1^st ed. New Delhi: Modern publishers; 2001. p. 362.
18.	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.