International Journal of Forensic Odontology

ORIGINAL ARTICLE
Year
: 2020  |  Volume : 5  |  Issue : 1  |  Page : 3--10

Gender determination using odontometric diagonal measurements of teeth: An analytical study


Ramhari Shankarrao Sathawane, Gunjan Vinod Moon, Rakhi Manoj Chandak, Ashish Babanrao Lanjekar, Runal Prakash Bansod, Vidyarjan Ashok Sukhdeve 
 Department of Oral Medicine and Radiology, SDKS Dental College and Hospital, Nagpur, Maharashtra, India

Correspondence Address:
Dr. Gunjan Vinod Moon
From the Department of Oral Medicine and Radiology, SDKS Dental College and Hospital, Nagpur, Maharashtra
India

Abstract

Background: Gender determination is one of the prime parameters in forensic identification. The feasibility of the nonreactive, mineralized part of teeth to resist mutilation and to survive deliberate, accidental, or natural change has led forensic experts to focus on the teeth as a possible source as forensic data in cases of fragmentary and mutilated human remains. Aim: The aim of this study is to determine gender using odontometric diagonal measurements of permanent maxillary and mandibular teeth. Objectives: To measure and evaluate sexual dimorphism by odontometric diagonal measurement of teeth. Materials and Methods: The study sample included a total of 80 maxillary and mandibular dental casts obtained by alginate impression from 40 participants (20 males and 20 females) in the age range of 19–35 years selected from the Central Indian population. Mesiobuccal-distolingual (MBDL) and distobuccal-mesiolingual (DBML) measurements of the right permanent maxillary and mandibular teeth excluding third molars were taken separately. All the measurements were taken using a Digital Vernier Caliper. Data were analyzed using discriminant function analysis. Results: It is found that the diagonal measurements are significantly greater in males than females. The highest percentage of overall accuracy rate of maxillary MBDL is followed by maxillary DBML, mandibular MBDL, and mandibular DBML. All the values of the mean tooth dimension of MBDL were greater than DBML. The overall accuracy rate of maxillary MBDL is 97.2% and mandibular MBDL is 95.2%. The overall accuracy rate of maxillary DBML is 96.56% and mandibular DBML is 94.21%. Conclusion: Diagonal measurements of teeth can be used for sex determination. The most significant variable is found to be MBDL measurements of maxillary and mandibular second premolars. It is the strongest predictor for gender determination.



How to cite this article:
Sathawane RS, Moon GV, Chandak RM, Lanjekar AB, Bansod RP, Sukhdeve VA. Gender determination using odontometric diagonal measurements of teeth: An analytical study.Int J Forensic Odontol 2020;5:3-10


How to cite this URL:
Sathawane RS, Moon GV, Chandak RM, Lanjekar AB, Bansod RP, Sukhdeve VA. Gender determination using odontometric diagonal measurements of teeth: An analytical study. Int J Forensic Odontol [serial online] 2020 [cited 2024 Mar 29 ];5:3-10
Available from: https://www.ijofo.org/text.asp?2020/5/1/3/288160


Full Text



 Introduction



Teeth are known for being the most resistant mineralized tissue against different agents for destruction.[1],[2] They are, therefore, often used as a part of reconstructive identification.[3] They are particularly useful in the determination of gender by using different odontometric techniques,[4] and are of real interest in case of major catastrophes when bodies are often damaged beyond recognition.[5],[6] Teeth are used for the estimation of age, sex, and the identification of an individual.[7] There are various methods used for the determination of sex of an individual, such as mandibular canine index and mesiodistal width measurements of maxillary incisor, canine, and first molar.[5],[8] Sex determination is one of the prime parameters in forensic identification.[9],[10] In general male teeth have found to be larger than those of the female.[5],[11] Sexual dimorphism refers to those differences in size, stature, and appearance between males and females that can be applied to dental identification because no mouths are alike.[12],[13],[14],[15]

However, width measurements, i.e. mesiodistal and buccolingual dimensions many a times pose problems in taking the measurements due to crowding, cervical abrasions, attrition, and interproximal wear facets, presence of dental calculus, etc., In such situations, diagonal teeth measurements are of utmost use and importance.[1],[6],[15] Therefore, the present study is aimed to determine gender by using the diagonal measurement of teeth and discriminant function. The objective of this study is to measure and to evaluate mesiobuccal-distolingual (MBDL) and distobuccal-mesiolingual (DBML) crown measurements of permanent maxillary and mandibular teeth for sexual dimorphism.

 Materials and Methods



The study comprised a total of 80 upper and lower jaw dental casts of 40 participants (20 males and 20 females) in the age group ranging from 19 to 35 years from a Central Indian population.

The sample size was derived using a formula (key article by Shankar et al.[10]) as follows:

[INLINE:1]

The notation for the formulae are:

n1= sample size of Group 1

n2= sample size of Group 2

σ1= standarddeviation of Group 1

σ2= standarddeviation of Group 2

△ = difference in group means

k = ratio = n2/n1

z1−α/2= two-sided z value (e.g. z = 1.96 for 95% confidence interval)

z1− β= power

Standard deviation (SD) of MBDL in males for tooth no 65 = 0.634

SD of MBDL in females for tooth no 65 = 0.521

△ = Difference in mean value = 10.76 – 10.38 = 0.38

k = 1

[INLINE:2]

=36.23 patients needed for the study

Therefore, 40 patients included in the study.

The sample patients were selected by convenience sampling from outpatient department (OPD) from Swargiya Dadasaheb Kalmegh Smruti Dental College and Hospital, Nagpur having fully erupted teeth from right permanent central incisor to the right second molar, without restoration, crowding of teeth, fractured teeth or orthodontic appliance and no developmental abnormalities that could affect odontometric measurements. The study was approved by the Institutional Ethics Committee, and the written consent was obtained from the participants.

Upper and lower jaw impressions were taken with alginate impression material followed by the preparation of models with dental stone. Study cast was labeled by putting OPD registration number. The investigators were single-blinded to the subsequent procedure. Using these models, mesiobuccal-distolingual or mesiolabioincisal-distolinguoincisal (MBDL) and distobuccal-mesiolingual or distolabioincisal- mesiolinguoincisal (DBML) measurements of seven right permanent teeth of each jaw except third molars were measured using Digital Vernier Caliper by one investigator at a different time and recorded in the pro forma. All values were rounded to two decimal places.

While placing the caliper parallel to the occlusal or incisal surface, the following points as defined by Hillson et al.[16] were considered as a guide during the measurements:

MBDL: The largest distance between the mesiobuccal corner of cement enamel junction points to the distolingual cornerDBML: The largest distance between the distobuccal corner of cement enamel junction point to the mesiolingual corner.

To assess the reliability of measurements, of 80 casts, 40 casts were randomly selected from the original sample casts, and the diagonal measurements were again obtained by the same observer in the presence of another observer. The obtained measurements were tallied with the first measurements. It was found that there was no difference in recorded measurements.

The collected data were subjected to the statistical analysis. The data were subsequently processed and analyzed using the Wintrap SPSS software version 24.0, USA (Wintrap Basic Polar Engineering and Consulting, USA Copyright 2014). Independent sample t-test was used to compare mean tooth sizes between males and females. The discriminant function analysis was carried out using various coefficients.

If the values obtained were greater than the sectioning point, the individual was considered a male, and if less than the sectioning point, the individual was considered a female.

The percentage of sexual dimorphism was calculated using the following equation:

Percentage of sexual dimorphism = ([xm/xf] − 1) × 100

where xm= mean male tooth dimension; xf= mean female tooth dimension.

Statistical significance was kept at P ≤ 0.05.

 Results



A total of 28 measurements were taken on 14 teeth (seven teeth from each jaw) of each individual included in this study. Measurements on the teeth of 40 individuals were analyzed using SPSS software, different test, and discriminant function.

[Table 1] shows descriptive statistics, percentage sexual dimorphism, t values and P values for MBDL and DBML crown diameters, respectively, for the seven teeth of all males and females. The highest percentage of sexual dimorphism for maxillary MBDL crown diameter is 22.41% seen in the second premolar, followed by 20.14% in the first premolar, and the lowest percentage of sexual dimorphism is 5.2% seen in central incisor. The highest mean tooth dimensions in male for maxillary MBDL is 11.53 mm and in the female is 10.26 mm seen in the first molar. The lowest mean tooth dimensions in male for maxillary MBDL is 6.41 mm and in the female is 5.90 mm seen in lateral incisor. The P value was found statistically highly significant for all seven teeth.{Table 1}

The highest percentage of sexual dimorphism for mandibular MBDL crown diameter of 18.64% is seen in the second premolar, and the lowest percentage of sexual dimorphism is 6.90% seen in lateral incisor. The highest mean tooth dimension in males for mandibular MBDL is 11.22 mm and in the female is 9.92 mm seen in the first molar. The lowest mean tooth dimension in males for mandibular MBDL is 5.69 mm and in the female is 5.04 mm seen in central incisor. The P value was found statistically highly significant for all seven teeth [Table 2].{Table 2}

On comparison of mean tooth dimensions between males and females for maxillary DBML, the highest percentage of sexual dimorphism is 25.47% seen in the second molar, and the lowest percentage of sexual dimorphism is 6.66% seen in lateral incisor. The highest mean tooth dimension in males for maxillary DBML is 10.59 mm and in the female is 8.53 mm seen in the first molar. The lowest mean tooth dimension in males for maxillary DBML is 6.45 mm and in the female is 6.02 mm seen in lateral incisor. The P value was found statistically highly significant for all seven teeth [Table 3].{Table 3}

The highest percentage of sexual dimorphism for mandibular DBML is 17.59% seen in the second premolar, and the lowest percentage of sexual dimorphism is 3.14% seen in lateral incisor. The highest mean tooth dimension in males for mandibular DBML is 10.74 mm and in the female is 9.54 mm seen in the first molar. The lowest mean tooth dimension in males for mandibular DBML is 5.48 mm and in the female is 5.21 mm seen in central incisor. The P value was found statistically “not significant” for lateral incisor and canine teeth [Table 4].{Table 4}

The mean tooth dimension among all participants for maxillary and mandibular MBDL, it showed that the highest mean tooth dimension of maxillary MBDL is 10.89 mm and mandibular MBDL is 10.57 mm seen in the first molar. The lowest mean tooth dimension of maxillary MBDL is 6.15 mm seen in lateral incisor, and mandibular MBDL is 5.36 mm seen in the central incisor. The P value for the second premolar, first molar, and second molar was found statistically not significant [Table 5].{Table 5}

On comparison mean tooth dimension among all subjects for maxillary and mandibular DBML, it is observed that the highest mean tooth dimension of maxillary DBML is 9.56 mm, and mandibular DBML is 10.14 mm seen in the first molar. The lowest mean tooth dimension of maxillary DBML is 6.25 mm seen in lateral incisor, and mandibular DBML is 5.35 mm in central incisor. The P value for the second premolar and first molar found to be statistically not significant [Table 6].{Table 6}

It is found that the second premolar (0.412) is the strongest predictor to determine sex, followed by first premolar (0.316), canine (0.219), second molar (0.212), and lateral incisor (0.003) which are the next important predictors for sex determination, whereas central incisor (−0.415) and first molar (−0.067) are less successful predictors [Table 7].{Table 7}

It is observed for mandibular MBDL that the second premolar (0.513) is the strongest predictor to determine sex followed by canine (0.319), first molar (0.215), second molar (0.060) and lateral incisor (0.051) which are the next important predictors for sex determination, whereas first premolar (−0.161) is less successful predictor [Table 8].{Table 8}

It is observed for maxillary DBML that the first premolar (0.491) is the strongest predictor to determine sex followed by second molar (0.219), first molar (0.191), lateral incisor (0.168), canine (0.002) and which are the next important predictors for sex determination, whereas central incisor (−0.412) and second premolar (−0.006) are less successful predictors [Table 9].{Table 9}

It is observed for mandibular DBML that the second molar (0.512) is the strongest predictor to determine sex followed by second premolar (0.492), central incisor (0.192), lateral incisor (0.104), first premolar (0.081) and first molar (0.018), which are the next important predictors for sex determination, whereas canine (−0.121) is less successful predictors [Table 10].{Table 10}

[Table 7], [Table 8], [Table 9], [Table 10] describe the distribution of seven of maxillary and mandibular teeth parameters with their standardized coefficient, structure matrix, unstandardized coefficient, raw coefficients, group coefficient in each of the two groups, i.e. males and females and sectioning point for MBDL and DBML crown diagonal dimension, where the sectioning point is derived as 0.

The canonical discriminant function coefficient indicates the unstandardized scores concerning the independent variables. It is the list of coefficients of the unstandardized discriminant equation. Each subject's discriminant score would be computed by entering his or her variable values (raw data) for each of the variables in the equation.

The unstandardized coefficient (b) is used to create the discriminant function score (y) (prediction equation), to classify new cases and added to the raw coefficient constant (a).

The discriminant function score was evaluated by using the equation as follows:

Y = a + b (x)

where x is the dimension of the tooth in mm.

a is raw coefficient (constant)

b is the unstandardized coefficient

The standardized coefficient is used to calculate the discriminant score for a given case (sexes). The structure matrix gives the correlations between the variables and discriminant functions. Group centroids are the mean discriminant score for each sex. The sectioning point is the average of male and female group centroids.

The standardized canonical discriminant function coefficient can be used to rank the importance of each variable. A high standardized discriminant function coefficient might mean that the groups differ a lot on that variable. The sign indicates the direction of the relationship.

Standardized canonical discriminant function coefficients indicate the relative importance of the independent variables in predicting the dependent. They allow comparing variables measured on different scales. Coefficient is used to calculate the discriminant score for the given case. The score is calculated in the same manner as a predicted value from linear regression, using the standardized coefficient and the standardized variables.

The distribution of the scores from each function is standardized to have a mean of zero and SD of one. The magnitudes of these coefficients indicate how strongly the discriminating variables affect the score.

[Table 11] illustrates the accuracy of sex determination with maxillary MBDL dimensions. It is observed that 100% of males and 95% of females were correctly classified with an overall accuracy of 97.2%. This demonstrates that a greater percentage of males were correctly identified using dimensions of maxillary MBDL.{Table 11}

[Table 12] illustrates the accuracy of sex determination with the mandibular MBDL dimension. It observed that 100% of males and 90% of females were correctly classified with an overall accuracy of 95.2%. This demonstrates that a greater percentage of males were correctly identified using dimensions of mandibular MBDL.{Table 12}

[Table 13] depicts the accuracy of sex determination with maxillary DBML dimensions. It is found that 95% of males and 85% of females were correctly classified with an overall accuracy of 96.56%. This demonstrates that a greater percentage of males were correctly identified using dimensions of maxillary DBML.{Table 13}

[Table 14] depicts the accuracy of sex determination with mandibular DBML dimensions. It is found that 90% of males and 85% of females were correctly classified with an overall accuracy of 94.21%. This demonstrates that a greater percentage of males were correctly identified using dimensions of mandibular DBML.{Table 14}

In the present study, the overall accuracy rate of maxillary MBDL is 97.2%. The overall accuracy rate of mandibular MBDL is 95.2%. The overall accuracy rate of maxillary DBML is 96.56%. The overall accuracy rate of mandibular DBML is 94.21%. This suggests that the highest percentage of overall accuracy rate of maxillary MBDL is followed by maxillary DBML, mandibular MBDL, and mandibular DBML.

 Discussion



Skull is possessed of hard structures, due to which it is the most maintained part of the skeleton. In addition to the skull, mandible along with teeth is also the commonly available intact bone. Thus, jawbones are used to differentiate sexes as they express strong sexual dimorphism.[17],[18]

Teeth, being the main component of the masticatory apparatus of the skull, are the most steady and hardest tissue in the body. The feasibility of the nonreactive, mineralized part of teeth to resist mutilation in postmortem scenario and to survive deliberate, accidental, or natural change has led forensic experts to focus on the teeth as a possible source for valuable forensic data in fragmentary and mutilated human remains.[19]

Teeth are known to be peculiar organs as they are the most durable tissue in the body made of mineralized tissue. Their durability, even with fire or blast and bacterial decomposition, makes them indispensable for forensic investigations.[20]

The coronal morphology and dimension of permanent teeth remain unchanged during growth and development. Hence, odontometric measurements can be used in determining the sex after the tooth has erupted.[21]

The male teeth are usually larger as compared to females. In the present study, it is found that male teeth dimensions are larger than female teeth dimensions, thus, exhibiting sexual dimorphism. These results are in accordance with various other studies revealing clear dimorphic differences between male and female teeth.[8],[22] In the present study, the overall accuracy rate of maxillary MBDL is 97.2%. The overall accuracy rate of mandibular MBDL is 95.2%. The overall accuracy rate of maxillary DBML is 96.56%. The overall accuracy rate of mandibular DBML is 94.21%. These findings concluded that the highest percentage of overall accuracy rate of maxillary MBDL is followed by maxillary DBML, mandibular MBDL, and mandibular DBML. In the present study, the overall classification accuracy rate for the male is 95% and for females 85%. This is also in concordance with the findings of a study by Rai and Anand (2007)[11] where in accuracy rate was 30.4% for males and 18.2% for females suggesting higher classification accuracy rate for males as compared to females.

 Conclusion



From the present study, the following conclusions are drawn:

Diagonal dimensions in all seven teeth of males exceeded that of females, thus exhibiting sexual dimorphism between the sexesOverall accuracy rate of maxillary MBDL is 97.2%Overall accuracy rate of mandibular MBDL is 95.2%Overall accuracy rate of maxillary DBML is 96.56%Overall accuracy rate of mandibular DBML is 94.21%The most significant variable contributing to sex determination is found to be maxillary and mandibular MBDL dimensions of the second premolar. This is the strongest predictor to determine sexFor maxillary DBML, it is the first premolar, and for mandibular DBML, it is the second molar. These are the second strongest predictors to determine sex.

The method applied in the present study “crown diagonal measurements” is simple, easy to perform, and inexpensive. It can, therefore, be applied in forensic odontology for establishing the sex identity of an individual.

Limitations of the study

The diagonal measurements might go wrong if the caliper is not positioned properly parallel to the tooth axis and requires more attention while taking measurementsSince the sample size of the present study is less, it is recommended to conduct further studies with a large sample size.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

References

1Zorba E, Moraitis K, Eliopoulos C, Spiliopoulou C. Sex determination in modern Greeks using diagonal measurements of molar teeth. Forensic Sci Int 2012;217:19-26.
2Acharya AB, Mainali S. Univariate sex dimorphism in the Nepalese dentition and the use of discriminant functions in gender assessment. Forensic Sci Int 2007;173:47-56.
3Vodanovic M, Demoz, Njemirovskij V, Keros J, Brkic H. Odontometrics: A useful method for sex determination in an archaeological skeletal population? J Archaeol Sci 2007;34:905-13.
4Khaitan T, Ramaswamy P, Sudhakar S, Smitha B, Uday G. Role of mandibular canines in establishment of gender. Egypt J Forensic Sci 2014;4:71-4.
5Naikoo FA, Chalkoo AH, Ahmad Z. Sexual dimorphism using mandibular canine in establishing sex identity among Kashmiri population-A clinical study. Int Arch Integrated Med 2017;4:11-5.
6Mujib AB, Tarigoppula RK, Kulkarni PG, Anil BS. Gender determination using diagonal measurements of maxillary molar and canine teeth in Davangere population. J Clin Diagn Res 2014;8:ZC141-4.
7Bakkannavar SM, Manjunath S, Nayak VC, Kumar GP. Canine index – A tool for sex determination. Egypt J Forensic Sci 2015;5:157-61.
8Metgud R, Surbhi NS, Patel S. Odontometrics: A useful method for gender determination in Udaipur population. J Forensic Investig 2015;3:1-5.
9Khangura RK, Sircar K, Singh S, Rastogi V. Sex determination using mesiodistal dimension of permanent maxillary incisors and canines. J Forensic Dent Sci 2011;3:81-5.
10Shankar S, Anuthama K, Kruthika M, Kumar VS, Ramesh K, Jaheerdeen A, et al. Identifying sexual dimorphism in a paediatric South Indian population using stepwise discriminant function analysis. J Forensic Leg Med 2013;20:752-6.
11Rai B, Anand SC. Gender determination by diagonal distances of teeth. Internet J Biol Anthropol 2007;1:1-4.
12Sonika V, Harshaminder K, Madhushankari GS, Sri Kennath JA. Sexual dimorphism in the permanent maxillary first molar: A study of the Haryana population (India). J Forensic Odontostomatol 2011;29:37-43.
13Gupta S, Chandra A, Gupta OP, Verma Y, Srivastava S. Establishment of sexual dimorphism in North Indian population by odontometric study of permanent maxillary canine. J Forensic Res 2014;5:1-4.
14Ayoub F, Shamseddine L, Rifai M, Cassia A, Diab R, Zaarour I, et al. Mandibular canine dimorphism in establishing sex identity in the lebanese population. Int J Dent 2014;2014:235204.
15Manchanda AS, Narang RS, Kahlon SS, Singh B. Diagonal tooth measurements in sex assessment: A study on North Indian population. J Forensic Dent Sci 2015;7:126-31.
16Hillson S, Fitzgerald C, Flinn H. Alternative dental measurements: Proposals and relationships with other measurements. Am J Phys Anthropol 2005;126:413-26.
17Ferembach D, Schwidetzky I, Stloukal M. Recommendations for age and sex diagnoses of skeleton. J Hum Evol 1980;1:517-49.
18Iscan MY. Forensic anthropology of sex and body size. Forensic Sci Int 2005;147:107-12.
19Lund H, Mörnstad H. Gender determination by odontometrics in a Swedish population. J Forensic Odontostomatol 1999;17:30-4.
20Williams PL, Bannister LH, Berry MM, Collins P, Dyson M, Dussek JE, et al. Gray's Anatomy: The Anatomical Basis of Medicine And Surgery. 38th ed. New York: Churchill Livingstone; 1995.
21Anuthama K, Shankar S, Ilayaraja V, Kumar GS, Rajmohan M, Vignesh. Determining dental sex dimorphism in South Indians using discriminant function analysis. Forensic Sci Int. 2011;212:86-9.
22Peckmann TR, Meek S, Dilkie N, Mussett M. Sex estimation using diagonal diameter measurements of molar teeth in African American populations. J Forensic Leg Med 2015;36:70-80.