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JPAFMAT 2008; 8(1). ISSN 0972‐5687
22
SIGNIFICANCE OF MESIODISTAL DIAMETER OF THE MANDIBULAR PERMANENT CANINE IN SEXUAL DIMORPHISM
Dr. Subhash Kaushal, MD, Professor & Head, Department of Anatomy, Govt. Medical College, Patiala Dr. Usha Chhabra, MD, Additional Professor, Department of Anatomy, Govt. Medical College, Patiala. Dr. Bindu Aggarwal, MD, Assistant Professor Department of Anatomy, Gian Sagar Medical College, Ram Nagar, Banur. Punjab. Dr. Sanjay Singla, MD, Medical Officer, Department of Cardiology, Govt. Medical College, Patiala.
Abstract
Teeth are known for being the most resistant mineralized tissue against different agents of destruction. They are useful in determination of gender by using different odontometric techniques. In cases where postcranial bones are fragmented or unavailable, measurements of the mandibular canine tooth can provide a mean of determining sex as amongst all the teeth, the mandibular canines are found to exhibit greatest sexual dimorphism. In the present study, the mesiodistal diameter of the mandibular canines was measured in 60 North Indian subjects (M: F:: 30: 30) in the age group of 17‐21 years. The mesiodistal diameter of the Indian population was compared with that of different populations. This comparison was done as factors such as race, sex, heredity; nutrition and environment are known to be responsible for tooth size variability. It was found that in all the populations, the mesiodistal diameter of the males exceeded that of the females.
Keywords: Mandibular, Canines, Mesiodistal diameter.
Introduction
Teeth are restricted to the jawed vertebrates and can be regarded as new acquisitions for seizing, holding and masticating food [1]. Except in mankind, teeth are necessary for survival in most mammals and other vertebrates, and longevity is related to the endurance of the dentition under the abrasive process of mastication [2].
Teeth are the most indestructible part of the body and exhibit the least turnover of natural structure, and are readily accessible for examination and do not need special dissection. Hence teeth provide excellent material in living and non‐ living populations for anthropological, genetic, odontological and forensic investigations [3].
The science dealing with establishing identity by teeth is popularly known as Forensic odontology or Forensic dentistry [4]. ‘Sexual dimorphism’ refers to those differences in size, structure and appearance between male and
female, at an equal age, which can be applied to dental identification, because no two mouths are alike [5].
The present study establishes the impact of the ‘sex factor’ on the morphometry of the mandibular canines. The result indicates that the dimorphism in mandibular canines can be of immense medico‐ legal use in identification.
Material and Methods
Selection Criteria
Sixty subjects, 30 males and 30 females in the age group of 17 – 21 years were selected for this study. This age group was selected, as attrition is minimal in this age group [6]. The study was conducted on the students of Government Medical College, Patiala.
Inclusion Criteria
Subjects with the following status of teeth were included in the study:
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1. Healthy state of gingiva and periodontium. 2. Caries free teeth. 3. Normal overjet and overbite. 4. Absence of spacing in the anterior teeth. 5. Normal molar and canine relationship.
INSTRUMENT
The measurements of teeth were taken on an anatomically sound basis. All measurements were taken using a vernier caliper, taking into account the error if any, in the instrument. The caliper used had a resolution of 0.02 mm. Also a divider with a fixing devise was used for taking the measurements.
Measurement Procedure
This method was adopted from Kaushal[7]. The various parameters of the teeth were measured using dividers with a fixing devise and vernier calipers with a resolution of 0.02 mm.
1. Making of study casts
Impressions of mandibular arches were taken in alginate impression material and later study casts were prepared with stone plaster. The measurements were conducted on these study casts using vernier calipers.
2. Measuring the width of the mandibular canines.
The width of the mandibular canines taken as the greatest mesiodistal width between the contact points of teeth on either side (Figure 1&2) of jaw was taken on the study casts. The data obtained was computed, tabulated and statistically analyzed with the purpose of establishing sexual dimorphism.
Fig 1 Right Canine Width
Fig 2 Left Canine Width
Observations
The mesiodistal diameter was measured from the study casts and the result showed that the mesiodistal diameter in the males was 7.23 mm on the right side and 7.38 mm on the left side.
Table No. 1: Statistical Significance of Left Mesiodistal Diameter
In the females the mesiodistal diameter was found to be 6.58 mm on the right side and 6.60 mm on the left side.
Sex Mean (mm)
± S.D.
‘t’stat ‘p’value Significance
Males 7.387 0.322 10.48 <0.001 Highly Significant Females 6.6 0.254
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Table No. 2: Statistical Significance of Right Mesiodistal Diameter
From the table No. 1, it is evident that the right canine width is found to be statistically significant for males and females.
From the table No. 2, it is evident that the left canine width is found to be statistically significant for males and females.
Discussion
The present study establishes the existence of a definite statistically significant sexual dimorphism in mandibular canines. The measurements of linear dimensions which includes the mesiodistal width of canine teeth has the advantage of being able to use a large sample of population because it is simple, inexpensive and easy to perform. Males exhibit larger mesiodistal width than females. It is consistent with Nair [8] who conducted a study on South Indian males and females in the age group of 16‐28 years and found that the canines in both jaws exhibited a significant sexual difference. Lew and Keng [9] give similar findings in their study on ethnic Chinese population with normal occlusions.
Gabriel [10] has stressed that any measurement of teeth unaccompanied by age, race and sex must be treated with great reserve. Amongst the significant findings that can be obtained from teeth are race, age, sex, habits and racial customs. Molnar [11] found the existence of a positive correlation between tooth wear and cultural factors.
The mesiodistal width of the mandibular canines of the Indian population was compared with that of other populations. Comparison between the different populations is done as variation in tooth size is influenced by genetic
and environmental factors such as race, sex, heredity, environment, secular changes and bilateral asymmetry
In spite of the tooth size variability factors, the studies conducted by Ghose and Baghdady [12] on Iraqi population, Sherfudin and Khan [13] on Saudi Arabian population, Lysell and Myrberg [14] on Swedish population and by Bishara [15] on populations of Egypt, Mexico and Lowa (United States) showed the consistent finding that the mesiodistal width of the mandibular canines is more in the males than the females and the difference is statistically significant.
Comparison of Mesiodistal Diameter of the Right Permanent Mandibular Canine
From the above table, it is evident that the right canine width as measured for males and females when compared are found to be statistically significant.
Table No. 3: Comparison of Mesiodistal Diameter of the Left Permanent Mandibular Canine
Population Male(mm) Female(mm)
Egypt 6.9 6.6 Mexico 6.9 6.4 Lowa (USA) 6.8 6.4 Iraq 7.04 6.82 Saudi Arabia 7.23 5.61 Sweden 7.0 6.62 India 7.38 6.60
From the above table, it is evident that the right canine width as measured for males and females when compared are found to be statistically significant.
Canines differ from other teeth with respect to survival and sex dichotomy. These differences probably are related to their function, which is different on an evolutionary basis from other teeth. In carnivores and most primates, the chief function of the canines is not masticatory, but related to threat of aggression. Survival was
Sex Mean (mm)
±S.D. ‘t’stat ‘p’value Significance
Males 7.231 0.376 7.34 <0.001 HighlySignificant Females 6.585 0.300
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thus dependant on canines especially in the males. Thus, in the present day humans, sexual dimorphism in mandibular canines is expected to be based on functional activity[16].
Moss and Salentijn[17] proposed that a longer period of amelogenesis in the males could be responsible for the dental dimorphism. Garn[18] found that it is the Y chromosome, which intervenes most in the size of teeth by controlling the thickness of dentine, whereas the X chromosome only comes into play concerning the thickness of enamel.
It can thus be concluded that the mesiodistal diameter of the permanent mandibular canines is a significant parameter in sexual dimorphism.
References
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