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 Table of Contents  
ORIGINAL ARTICLE
Year : 2015  |  Volume : 27  |  Issue : 3  |  Page : 405-411

Sexual dimorphism in permanent maxillary and mandibular canines and intermolar arch width: Endemic study


1 Department of Oral Medicine and Radiology, Darshan Dental College and Hospital, Udaipur, Rajasthan, India
2 Department of Oral Medicine and Radiology, Sidhdhpur Dental College and Hospital, Sidhdhpur, Gujarat, India

Date of Submission23-Feb-2015
Date of Acceptance06-Nov-2015
Date of Web Publication25-Nov-2015

Correspondence Address:
Bhargav Selarka
Department of Oral Medicine and Radiology, Darshan Dental College and Hospital, Udaipur, Rajasthan
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0972-1363.170473

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   Abstract 

Aims and Objectives: The purpose of this study was to investigate whether dimorphism of permanent mandibular and maxillary canine teeth as well as intercanine and intermolar distance plays a role in establishing sex identity. Materials and Methods: Four hundred volunteers comprising 200 males and 200 females, with age ranging from 18 to 50 years, were selected. The greatest mesiodistal width of the canine teeth and the distance between the tips of canines of both arches and intermolar arch width were measured using vernier caliper with 0.02 mm resolution. All data were tabulated and analysis done by "t" test. Results: The widths of the mandibular and maxillary right and left canine teeth were almost bilaterally symmetrical in females and males. The mean values for left and right mandibular and maxillary canine widths were less in females than in males and the differences were statistically significant. The mean values for mandibular and maxillary intercanine and intermolar distances were less in females than in males and the differences were statistically significant (P < 0.001). Conclusion: The present study establishes a statistically significant sexual dimorphism in maxillary and mandibular canines and intermolar arch width. It can be concluded that standard canine index is a quick and easy method for sex determination.

Keywords: Dimorphism, intermolar arch width, maxillary and mandibular canine, sexual dimorphism


How to cite this article:
Syed MA, Selarka B, Tarsariya V. Sexual dimorphism in permanent maxillary and mandibular canines and intermolar arch width: Endemic study. J Indian Acad Oral Med Radiol 2015;27:405-11

How to cite this URL:
Syed MA, Selarka B, Tarsariya V. Sexual dimorphism in permanent maxillary and mandibular canines and intermolar arch width: Endemic study. J Indian Acad Oral Med Radiol [serial online] 2015 [cited 2019 Dec 8];27:405-11. Available from: http://www.jiaomr.in/text.asp?2015/27/3/405/170473


   Introduction Top


Sexual dimorphism is a phenotypic differentiation between males and females of the same species. Sex difference is a distinction of biological and/or physiological characteristics associated with either males or females of a species. [1],[2] In 1871, Charles Darwin advanced the theory of sexual selection, which related sexual dimorphism with sexual selection. Externally, the most sexually dimorphic portions of the body are the chest, the lower half of the face, and the area between waist and knees. [3],[4] To establish the sex of a victim is an essential stage in identification. Teeth are an excellent material in living and non-living populations for anthropological, genetic, odontologic, and forensic investigations as they are the hardest and chemically most stable tissues in the body. They exhibit the least turnover of natural structure and are readily accessible for examination. In major disasters where postcranial bones are fragmented, measurement of mesiodistal width of the mandibular and maxillary canine teeth and intercanine distance provides evidence of sex identification due to dimorphism. Canine size is a traditional measure of sex difference in primates because the canine is invariably the most dimorphic of the teeth. [5],[6],[7],[8] Hence, the present study has been aimed to measure the mesiodistal diameter of canine, intercanine width, and to determine the intermolar arch width in both males and females, in the maxillary and mandibular teeth, so as to establish canine measurement variation and intermolar arch width in sex determination.


   Aims and Objectives Top


  • To determine the maxillary and mandibular mesiodistal dimensions of the right and left canines in males and females intraorally and on the casts.
  • To determine the maxillary and mandibular intercanine width in males and females intraorally and on the casts.
  • To determine the maxillary and mandibular intermolar arch width between the left and the right first molars in males and females intraorally and on the casts.
  • To determine the average maxillary and mandibular canine index (CI).
  • To determine whether there is any difference in the CI and the intermolar arch width in males and females.

   Materials and Methods Top


The present study was conducted on 800 dental casts obtained from 400 volunteers. The males and females were equally distributed (200 males and 200 females) and their age group ranged between 18 and 50 years. All the subjects were selected randomly from those patients attending the OPD who were Indians and residents of Navi Mumbai. The significant exclusion criteria employed for selection of the study sample were the presence of partially erupted or ectopically erupted teeth, patients with dental or occlusal abnormalities (such as rotation, crowding, occlusal disharmony, etc.), teeth showing physiologic or pathologic wear and tear (e.g. attrition, abrasion, abfraction, erosion), and patients with deleterious oral habits (like bruxism). Maxillary and mandibular canine width, intercanine distance, and intermolar arch width were measured first intraorally and then on the cast by using a vernier caliper with a resolution of 0.02 mm. Data collected were tabulated according to gender and sides and statistically analyzed [Figure 1] [Figure 2] [Figure 3] [Figure 4] [Figure 5] [Figure 6].
Figure 1: Measurement of mesiodistal width of maxillary canine by clinical examination

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Figure 2: Measurement of mesiodistal width of maxillary canine on cast

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Figure 3: Measurement of intercanine width by clinical examination

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Figure 4: Measurement of intercanine width on cast

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Figure 5: Measurement of intermolar width by clinical examination

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Figure 6: Measurement of intermolar width on cast

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Various formulae used for analysis

Canine index

CI was calculated using the formula:



Sexual dimorphism in right and left mandibular and maxillary canines

Sexual dimorphism in the right and left mandibular and maxillary canines was calculated using the formula given by Garn and Lewis as follows:

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

where Xm = Mean value of male canine width and Xf = Mean value of female canine width.


   Results Top


This study was conducted on 400 volunteers equally distributed between 200 males and 200 females. Maxillary and mandibular impressions were made of all subjects; thus, 800 casts were made (400 maxillary and 400 mandibular). Measurements were made using vernier caliper and the following results were obtained.

The mean maxillary right canine width in males was found to be 7.944 ± 0.312 mm (intraorally) and 7.955 ± 0.317 mm (on the cast) and that in females was 7.346 ± 0.378 mm (intraorally) 7.356 ± 0.375 mm (on the cast) [Table 1]. The mean maxillary left canine width in males was found to be 7.953 ± 0.310 mm (intraorally), and 7.966 ± 0.313 mm (on the cast) and that in females was 7.354 ± 0.371 mm (intraorally) and 7.372 ± 0.368 mm (on the cast) [Table 2]. The mean mandibular right canine width was found to be 7.017 ± 0.409 mm in males and 6.374 ± 0.378 mm in females when measured intraorally and 7.032 ± 0.407 mm in males and 6.396 ± 0.380 mm in females when measured on the casts [Table 3]. The mean mandibular left canine width was found to be 7.037 ± 0.421 mm in males and 6.392 ± 0.371 mm in females when measured intraorally and 7.047 ± 0.414 mm in males and 6.414 ± 0.372 mm in females when measured on the casts [Table 4]. In the present study, it is observed that whenever mesiodistal canine width for the maxillary canines was greater than 7.8 mm and that for the mandibular canines was greater than 7.2 mm, the probability of sex being male was 100%.
Table 1: Maxillary right canine width

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Table 2: Maxillary left canine width

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Table 3: Mandibular right canine width

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Table 4: Mandibular left canine width

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In the present study, the intercanine distance was found to be greater in males compared to females for both maxilla and the mandible. The mean maxillary intercanine width was 36.21 ± 1.29 mm in males and 32.84 ± 1.14 mm in females (intraorally) and 36.22 ± 1.28 mm in males and 32.86 ± 1.13 mm in females (on the cast) [Table 5]. The mean mandibular intercanine distance was 26.52 ± 1.21 mm in males and 24.17 ± 1.15 mm in the females (intraorally) and 26.53 ± 1.22 mm in males and 24.18 ± 1.14 mm in females (on the cast) [Table 6].
Table 5: Maxillary intercanine distance

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Table: 6 Mandibular intercanine distance

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In the present study, the maxillary and mandibular CI (MxCI and MnCI, respectively) showed no statistically significant difference between the right and left sides. But there was a difference between MxCI and MnCI, the latter being higher which was statistically highly significant; hence, CI has been implicated as a tool for sexual dimorphism. In the present study, the right MxCI was found to be 0.215 ± 0.012 (males) and 0.223 ± 0.023 (females) intraorally and 0.214 ± 0.022 (males) and 0.223 ± 0.021 (females) on the casts [Graph 1]. The left MxCI was found to be 0.214 ± 0.015 (males) and 0.223 ± 0.026 (females) intraorally and 0.211 ± 0.022 (males) and 0.224 ± 0.033 (females) on the casts [Graph 2]. The right MnCI was found to be 0.263 ± 0.099 (males) and 0.263 ± 0.012 (females) intraorally and 0.261 ± 0.016 (males) and 0.264 ± 0.019 (females) on the casts [Graph 3]. The left MnCI was found to be 0.265 ± 0.016 (males) and 0.264 ± 0.015 (females) intraorally and 0.267 ± 0.017 (males) and 0.265 ± 0.015 (females) on the casts [Graph 4].









The maxillary intermolar arch width was found to be 53.33 ± 1.68 mm in males and 49.47 ± 1.90 mm in females (intraorally) and 53.36 ± 1.68 mm in males and 49.50 ± 1.90 mm in females (on the casts). The largest maxillary intermolar arch width was 59.40 mm in males and 54.54 mm in females, whereas the least was 47.08 mm in males and 44.44 mm in females [Graph 5]. The mandibular intermolar arch width was found to be 46.65 ± 2.52 mm in males and 42.87 ± 1.92 mm in females (intraorally) and 46.66 ± 2.52 mm in males and 42.88 ± 1.92 mm in females (on the casts). The largest mandibular intermolar arch width was 52.36 mm in males and 47.36 mm in females, whereas the least was 41.36 mm in males and 32.02 mm in females. The difference in the mean was statistically highly significant [Graph 6].





The percentage of sexual dimorphism was calculated by using Garn and Lewis formula and according to the present study, the sexual dimorphism for the maxillary canines on the right side was 8.23% intraorally and 8.20% on the cast, and for the left side was 8.23% intraorally and 8.09% on the cast [Graph 7]. The percentage of sexual dimorphism for the mandibular canines on the right side was 10.16% intraorally and 10.13% on the cast, and on the left side was 10.05% intraorally and 9.44% on the cast. These percentages on the right and left sides were statistically significant, with the sexual dimorphism being slightly greater on the right side than the left side [Graph 8].






   Discussion Top


This study was conducted on 400 patients (200 males and 200 females) with age ranging from 18 to 50 years. Mesiodistal canine width, intercanine distance, and intermolar arch width were measured intraorally and on the casts. A total of 16 parameters were measured in each patient. Maxillary and mandibular CI and sexual dimorphism were calculated using the formulas mentioned earlier. Gustafsson and Lindenfors [3] and Frayer and Wolpoff [5] concluded in their studies that the mean values for left and right mandibular and maxillary canine widths were less for females than for males. We obtained similar results in our study, supporting the previous study results. Astete et al.[9] concluded in their study that the mean values for mandibular and maxillary intercanine and intermolar distances for females were less than for males. Our study also gave a similar result. Teschler-Nicola [10] and Garn et al.[11] concluded in their studies that the average score for right and left maxillary and mandibular CI was higher in females compared to males due to less mesiodistal width and intercanine width in females. Our study also gave a similar result. Omar and Azab [12] and Kaushal et al.[13] concluded that the mandibular canines showed higher percentage of sexual dimorphism. Our study also gave a similar result. It was concluded in the studies of Garn et al.[14] and Anderson and Thompson [15] that sexual dimorphism was slightly greater on the right side than the left side. Our study also gave a similar result.


   Conclusion Top


The study was conducted to establish sexual dimorphism from permanent maxillary and mandibular canines and intermolar arch width using the mesiodistal width of canines, intercanine distance, and intermolar arch width between males and females. To summarize, the present study gave the following results:

  • The widths of the mandibular and maxillary right and left canine teeth were almost bilaterally symmetrical in females and males.
  • The mean values for left and right mandibular and maxillary canine widths were less for females than for males and the differences were statistically significant.
  • The mean values for mandibular and maxillary intercanine and intermolar distances for females were less than for males and the differences were statistically significant.
  • Average scores for right and left maxillary and mandibular CI were higher in females compared to males due to less mesiodistal width and intercanine width in females.
  • The mandibular canines showed higher percentage of sexual dimorphism.
  • The sexual dimorphism was slightly greater on the right side than the left side.
In the emerging field of forensic odontology, India relies a lot on inexpensive and easy means of identification of persons from fragmented jaws and dental remains. It is in such situations that the dentist can be called upon to render expertise in forensic science. However, more studies have to be carried out with more samples to support our observation and standardize definite values for sex identification with reference to mesiodistal width of canine, intercanine distance, and intermolar arch width in both males and females. Thus, sex determination can be done with the help of canine teeth and first molars in forensic dentistry to help maintain law and render justice.

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

Nil.

Conflicts of interest

There are no conflicts of interest.

 
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Sexual Dimorphism. Available from: http://en.wikipedia.org/wiki/Sexual_dimorphism. [Last accessed on 2015 Jan 23].  Back to cited text no. 1
    
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Vodanoviæ M, Demo Ž, Njemirovskij V, Keros J, Brkiæ H. Odontometrics: A useful method for sex determination in an archaeological skeletal population. J Archaeol Sci 2007;34:905-13.  Back to cited text no. 6
    
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Rösing FW. Sexing immature human skeletons. J Hum Evol 1983;12:149-55.  Back to cited text no. 7
    
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Williams′s PL, Bannister LH, Berry MM, Collins P, Dyson M, Dussek JE, et al. In: The Teeth. Gray′s Anatomy. 38 th ed. London: Churchill Livingstone; 2000. p. 1699-700.  Back to cited text no. 8
    
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Astete JC, San Pedro VJ, Suazo GI. Sexual dimorphism in the tooth dimensions of Spanish and Chilean peoples. Int J Odontostomat 2009;3:47-50.  Back to cited text no. 9
    
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Omar A, Azab S. Applicability of determination of gender from odontometric measurements of canine teeth in a sample of adult Egyptian population. Cairo Dent J 2009;167:180.  Back to cited text no. 12
    
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Kaushal S, Patnaik VV, Agnihotri G. Mandibular canines in sex determination. J Anat Soc India 2003;52:119-24.  Back to cited text no. 13
    
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    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]
 
 
    Tables

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



 

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