Journal of the Anatomical Society of India

ORIGINAL ARTICLE
Year
: 2020  |  Volume : 69  |  Issue : 1  |  Page : 21--24

Study on mandibular parameters of forensic significance


D Sreelekha1, D Madhavi2, S Swayam Jothi3, A Vijayalakshmi Devi4, K Srinidhi5,  
1 Department of Anatomy, Sree Balaji Medical College and Hospital, Chrompet, Chennai, Tamil Nadu, India
2 Department of Anatomy, Guntur Medical College, Guntur, Andhra Pradesh, India
3 Department of Anatomy, Shri Sathya Sai Medical College, Kanchipuram, Tamil Nadu, India
4 Department of Anatomy, Siddhartha Medical College, Vijayawada, Andhra Pradesh, India
5 Housesurgeon, NRI Medical College, Vijayawada, Andhra Pradesh, India

Correspondence Address:
Dr. D Madhavi
Department of Anatomy, Guntur Medical College, Guntur, Andhra Pradesh
India

Abstract

Introduction: Bones often survive the process of decay and therefore provide the major evidence of human age and sex after death. The identification of human skeletal remains is a critical problem and is very important in medico-legal and anthropological works. The determination of sex of an individual is important and necessary both in the living and dead for medico-legal purposes. The aim of this study is to measure and analyze the various parameters of the mandible and to assess the reliability of the above parameters in terms of percentage accuracy in sex determination. Material and Methods: A total of 106 whole-adult human mandibles of unknown sex, between the age group of 18–60 years, were collected and studied at the Department of Anatomy and Forensic Medicine, Guntur Medical College, Guntur from 2014 to 2015. The following parameters studied were symphyseal height, mandibular body length, bicondylar diameter, bigonial diameter, inter incisor width, and mandibular angle. Results: Of the six parameters studied, highly significant (statistically) difference in sex was observed in bigonial diameter (82.15% accuracy) and mandibular angle (81.5% accuracy). Discussion and Conclusion: The inference of the study is that no single parameter gives 100% accuracy in the determination of the sex of the individual. Hence, a judicious consideration of the highly significant parameters of the mandible may be taken into account in the determination of the sex of the individual.



How to cite this article:
Sreelekha D, Madhavi D, Jothi S S, Devi A V, Srinidhi K. Study on mandibular parameters of forensic significance.J Anat Soc India 2020;69:21-24


How to cite this URL:
Sreelekha D, Madhavi D, Jothi S S, Devi A V, Srinidhi K. Study on mandibular parameters of forensic significance. J Anat Soc India [serial online] 2020 [cited 2021 May 11 ];69:21-24
Available from: https://www.jasi.org.in/text.asp?2020/69/1/21/282302


Full Text



 Introduction



The mandible is a single bone forming the caudal part of the facial skull.[1]

The only bone in the skull with the exception of the tympanic ossicles that is capable of separate movement. It is composed of a thick outer shell of dense bone, with a small amount of cancellous tissue contained within it, and hence that its body is cut with difficulty by bone forceps. It resists decay longer than the other parts of the skeleton, which accounts for the fact that it is often the sole representative of the bones of the face in specimens from strata of past geological periods.[2] Sex can be more accurately determined after the attainment of puberty. The differences are well marked in the bony pelvis and skull. Mandible next to the pelvis in human remains will help us in the identification of age, sex, and race.[3] When the entire skeleton is available, sex can be determined up to 100% accuracy but in cases of mass disasters where usually fragmented bones are found, sex differentiation with 100% accuracy is not possible.[4],[5] Recognizable sex differences do not appear until after puberty except in the pelvis, and the accuracy from this bone is about 75% to 80%.

In the skull, features are modified by senility. According to Krogman, the degree of accuracy in sexing adult skeletal remains in the entire skeleton is 100%, pelvis alone is 95%, skull alone is 90%, pelvis plus skull is 98%, and long bones alone 80%.[6]

Sex determination based only on characteristics of teeth and their supporting structures had been a difficult task, whereas X-ray examination of the mandible gives definitive information about the sex. The mandibular condyles are smaller in females. By radiological examination, sex determination of skull is possible to the extent of 88%.[7]

Aim

The aim is to measure and analyze the various parameters of the mandible under study and to assess the reliability of the above parameters in terms of percentage accuracy in sex determination.

 Material and Methods



After obtaining institutional ethical committee clearance, 106 whole-adult human mandibles of unknown sex, between the age group of 18–60 years were collected and studied at the Department of Anatomy and Forensic Medicine Guntur Medical College, Guntur.

Based on morphological features, the mandibles were first categorized as male and female. The mandibles with prominent bony markings and everted mandibular angle were categorized as male and those with relatively smooth and less prominent markings with inverted or straight mandibular angle were categorized as female mandibles. The following parameters were carefully measured and studied using measuring scale, Vernier callipers, and goniometer [Figure 1]:{Figure 1}

symphyseal heightmandibular body lengthbicondylar diameterbigonial diameterinter incisor widthmandibular angle.

Symphyseal height or chin height

The straight distance between the infradentale and gnathion.[8] Infradentale is the highest anterior point of the alveolar process of mandible between the two central incisors in the midline. Gnathion is the most anterior and inferior point of the bony chin.[9] Instrument used – sliding caliper [Figure 2] determined by known statistical standards.{Figure 2}

Mandibular body length

From the most anterior point on the symphysis menti to an imaginary point formed by the posterior margin of the ramus and the anteroposterior axis of the body and measured parallel to the axis.[10] Instrument used-sliding caliper [Figure 2].

Bicondylar breadth

It measures the straight distance between two condylia laterale.[8] Condylia laterale is the lateral most point of the head of the condyle of the mandible.[9] Instrument used – sliding caliper [Figure 2].

Bigonial breadth

It measures the straight distance between two gonia. Instrument used – sliding caliper.[8] Gonion is the intersection of the lines tangent to the posterior margin of the ascending ramus and the mandibular base [Figure 2].[9]

Inter incisor width

The width of the dental arch measured between the points of contact between the lateral incisor and canine on each side.[10] Instrument used – sliding caliper [Figure 2].

Mandibular angle

Measures the angle made by ramus with the body when placed on the surface.[8] Instrument used – goniometer [Figure 2].

Observation

The 106 mandibles chosen for the study were classified based on morphological features into 84 males and 22 females. The range, mean, and standard deviation (SD) for each of the six parameters for male and female mandibles was calculated [Table 1].{Table 1}

Data management and statistical analysis

All the six parameters were accurately measured and tabulated, and the 106 mandibles were classified as males (84) and females (22) based on morphological features. The range, mean, and SD of each of the parameters for the male and female mandibles were calculated, as shown in [Table 1]. Independent sample t-test was applied and the P value of significance is noted, as shown in [Table 2]. For the parameters that showed significance, using mean and SD, a “calculated range” was arrived at by the formula “Mean ± 3SD.” A calculated range for male (p and q) and for female (r and s) was obtained. From these values, the minimum in male range and the maximum in the female range were taken as “demarking points,” and the limiting point was determined by known statistical standards. According to the standard methods followed by previous workers, the limiting point is an absolute value found within the range of the demarking points [Table 3]. The limiting point was so chosen that the vast number of male mandibles showed values greater than it and the bulk of female mandibles showed values lesser than the chosen limiting point. Based on the limiting point for each parameter, the percentage accuracy [Table 4] of the sex was calculated by taking the mandibles whose values were more than the limiting factor as males and those values less than the limiting factor as females.{Table 2}{Table 3}{Table 4}

 Results



Of the six parameters studied, highly significant (statistically) difference in sex was observed in bigonial diameter (82.15% accuracy) and mandibular angle (81.5% accuracy).

 Discussion



Bigonial diameter

In the present study, the mean bigonial diameter for males was 89.33 mm and for females was 77.8 mm with a P = 0.000, which was very highly significant.

Flossie and Sayee in 2000, on the south Indian population, studied that the bigonial diameter in males were higher than females with a very highly significant P = 0.001.[11] Ongkana and Sudwan in 2009 and Sivaprakash in 2012 observed similar results with a highly significant P value.[12],[13] Datta et al. in a study on 50 bones, found the mean bigonial breadth to be 9.6 cm and 8.9 cm in males and females, respectively.[14]

The results of the present study were in accordance with the previous studies.

Mandibular angle

In the present study, the average male mandibular angle was 106.8° and in females was 116.36° with a P = 0.000, which was very highly significant. The female value was found to be higher than in males.

In earlier studies by Prakash and Abdi in 1987, it was observed that the mean mandibular angle was more in females 123° than males 118.6°.[15] Mbajiorgu in 2005 and Sivaprakash in 2012 also arrived at similar findings.[13],[16] Ranganath et al. found that the mean mandibular angle in males was 110.68° and for females was 114.53°.[17]The values of our study were similar to the results of Ranganath et al. Similar to the earlier works; it showed a higher female value than males and a very highly statistically significant difference.

Percentage accuracy

In the present study, the two variables, bigonial diameter, and mandibular angle showed the highest percentage accuracy of 82.15% and 81.50%, respectively, in determining the sex of the mandibleHanihara working on Japanese mandibles, was able to classify the sex of 85.6% mandibles using four mandibular parameters.[18] In a study done by Giles on American mandibles, he was able to classify the sex of mandibles in 83.2% of the cases by using three variables and 84.1% of the cases by using five variables.[19] In a study done by Sivaprakash in South Indian mandibles, he was able to sex the mandible in 83% of cases by using ten variables and 85.5% of the cases using three variables.[13]

 Conclusion



The identification of gender from skeletal remains is of paramount importance in anthropological and medico-legal aspects and can be done based on morphological features or parametrical analysis or as a judicious combination of both as in the present study.

All the parameters measured were higher in male mandibles compared to female mandibles except for mandibular angle, which showed higher female valuesStatistically significant differences were observed in five parameters, i.e., symphyseal height, mandibular body length, bicondylar diameter, bigonial diameter, and mandibular angleEvery parameter, independent of the other parameters, provides a certain percentage of certainty about the sex of the mandible. Hence, the percentage accuracy of the above five significant parameters was calculated precisely by methods followed by earlier workers. The results were that symphyseal height gave a percentage accuracy of 66.8%, mandibular body length of 68%, bicondylar diameter of 67.5% bigonial diameter of 82.15%, and mandibular angle of 81.5% accuracyHowever, since no single parameter can provide certainty of the sex of the mandible, and as suggested by earlier workers also, a combination of factors is to be considered in determining the genderThe two variables, bigonial diameter, and mandibular angle showed higher percentage accuracy in determining the sex of the mandible.

Limitation of the study

As the sample size of female mandibles is small, further studies with a larger or equal male and female sample size may be done to arrive at a more accurate conclusion of the significant parameters. Furthermore, in the present study as no single parameter provides certainty of the sex of the mandible, a combination of parameters needs to be considered in determining the gender.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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