Journal of International Academy of Forensic Science & Pathology

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1 Journal of International Academy of Forensic Science & Pathology () ISSN Sexual Dimorphism of Adult Mandibles: A Forensic Tool. S.Jembulingam.,M.S.Thenmozhi Department of Anatomy,Saveetha Dental College,Chennai 77 *Corresponding Author: S.Jembulingam. Department of Anatomy,Saveetha Dental College,Chennai 77. India. Jembus2010@gmail.com Accepted: Dec 08, 2015 Published: 27 th Dec Original Article Citation: S.Jembulingam.,M.S.Thenmozhi.Sexual Dimorphism of Adult Mandibles:A Forensic Tool. Vol 03. No 03. Copyright: 2016 S.Jembulingam. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution and reproduction in any medium, provided the original author and source are credited. ABSTRACT INTRODUCTION: Identifying and determining the sex of the skeletal remains is an important aspect in the arena of forensic studies. The mandible is the largest, strongest bone of the skull which is persistent even after the death of the individual and forms a significant source of information about sexual dimorphism. AIM: To study the sexual dimorphism in adult mandible using Morphological and Metric parameters and to Utilize it as forensic tool for identification of sex of the skeletal remains in crime scenes. OBJECTIVES: To determine the sex of the skull with the help of morphological factors like Gonial angle, Gonial flare, Symphysis menti and posterior ramus flexure and simple metric measurements like the Bigonial width and Bicondylar width METHODS: Around 50 completely dry Mandibles of Indian origin where assessed for morphological features like Symphysis menti, Muscular markings and gonial flare and metric measurements like Bicondylar width and Bigonial width were measured using Vernier calliper STATISTICAL ANAYLSIS: The data was expressed in Mean±SD and was subjected to t-test using SPSS (Version 20) software.

2 RESULTS: There was a significant difference in the measurements Bicondylar width and Bigonial width in the mandible and also the morphological parameters which had a p<0.005 which was test by independent t test using SPSS software. CONCLUSION: The present study revealed that sex of the human mandible can be determined through morphological and metric methods and can be used as a forensic tool. KEYWORDS: Mandible,Forensics,Metric Parameters,Bicondylar Width,Bigonal Width,Sex Determination. INTRODUCTION: Identifying and determining the sex of the skeletal remains of human individuals is very serious problem in the forensic study. The Bones an important evidence which not only helps in identification of the age and height of the individual but some bones like mandible also help in identification of the sex of the individual too.thus it proves to be a genuine evidence for medicolegal cases which comes to the court of justice. Once the sex of the individual is identified then it would be easier for the investigators to investigate in the crime scene or in surveying of dead people in a mass disaster like earthquake or tsunami [1].It is a proven that pelvis bone and skull bones are important bones for sex determination. But in many scenario, we don t get the complete pelvis or skull. In such cases mandible can be used for determination of the sex of the individual.the mandible show the maximum sexual dimorphism next to pelvis [2]. The mandible is a sturdy, indestructible and a stable bone which is persistent even after the death of the individual. So in Major disasters mandible retains its shape and can be used for sex determination. The mandible is the largest, strongest and lowest bone of the skull. In the midline on the anterior part of the mandible is a slight linear elevation, an indication of the mandibular symphysis, formed during facial development. There are two rami in the posterior parts bearing the conical projection called the coronoid and condylar process. Generally morphological and mathematical techniques are used to identify the sex of the individual having the mandible based on the different features like size of bone [3], angle of Symphysis menti, gonial angle [4][5], and muscular attachment marking [4][6][7]. MATERIALS AND METHODS: This study was conducted on 50 dry adult human mandibles of South Indian origin which were in a good condition available from the anthropology museum of Saveetha Dental College and Hospital, Chennai. The sex of the skull where unknown and the study plan are as it follows: A) In the First step of the study the mandibles where classified into male and female mandibles on the basis of morphological features: Shape of the angle of symphysis menti, whether square or rounded. This is the angle produced in the midline by the symphysis. B) Gonial angle, whether inverted or everted The angle in the lower end of Ramus. C) Muscular marking, whether less/more prominent

3 The markings made by the muscular attachment. The Findings and sex was recorded. On the basis of step one, the mandibles where divided into two groups. Where 20 where placed in group 1 and 20 where placed in group 2 and rest of the 10 mandibles where excluded from the study due to its incomplete nature. Group 1: Male This group had twenty male human mandibles based on recorded observation Group 2: Female This group had twenty female human mandibles based on the recorded observations. Then mathematical parameters where measured using Vernier calliper of 0.1mm precision. The parameters used where: BICONDYLAR BREADTH the distance between the most lateral points of the two condyles BIGONIAL BREADTH the straight distance between the two Gonia Then DATA management and statistical analysis were done after all measurements were recorded for the mandibles. A student t test was performed. Mean and standard deviation were calculated for both the genders.p value was determined to assess the significance of the observation. [Image 1] [Image 2] OBSERVATION: The observations were recorded and compiled using SPSS (Version 20) software and are tabulated [Table 1] [Table 2] [Table 3] [Table 4]

4 RESULTS: On the basis of the study done on the mandibles of south Indian origin, following results were obtained: Based on morphological parameters, out of 50 skulls, 29 were found to have male mandibles which had a prominent muscular marking, a posterior Ramus flexure, the symphysis menti was found to be square and gonion flare was everted. 21 out of 50 skulls was found to be female mandible which has a smooth muscular marking, no posterior Ramus flexure, the symphysis menti was found to be round and gonion flare was inverted. So out of 50 skulls 29 skulls had a male mandible while other 21 was found to be having a female mandible. Out of the 50 skulls only 40 (20 male and 20 female) were taken into consideration after excluding the damaged and incomplete mandibles. In the present study conducted on mandibles of south Indian origin, the Bicondylar width was observed to be ± 0.51cm in males and ± 0.55cm in females. The independent t test was done to compare the two sets of means and P value was less than (p<0.0001) which proves to be statistically significant. (Table 2) In the present study conducted on mandible of south Indian origin, the Bigonial width was observed to be 9.40 ± 0.55cm in males and 8.35 ± 0.29cm in females. The independent t test was done on to compare the two sets of means and P value was less than (p<0.0001) which proves to be statistically significant. (Table 3) In the present study conducted on mandible of south Indian origin Mandibular length was observed to be 7.84 ± 0.45cm in males and 7.20 ± 0.54cm in females. The independent t test was done on to compare the two sets of means and P value was less than (p<0.0001) which proves to be statistically significant. DISCUSSIONS: The skull which is primary evidence in a lot of medicolegal issues and proves to show sexual dimorphism other than pelvis in the human body. So the mandibles which is the strongest and lowest, movable bone of the skull also show sexual dimorphism which helps in identification of the sex of the individual in forensic studies. Morphologically male mandibles have square symphysis menti [8], gonion flare [9] was everted, a posterior ramus flexure was present and there was a prominent muscular marking. While female mandibles have round symphysis menti, gonion flare was inverted, a posterior ramus flexure was absent and there was a smooth prominent muscular marking. The mandibles was assessed using different morphological and mathematical parameters [10] like Bicondylar length, Bigonial length and minimum ramus height There were studies done on morphological parameter like the symphysial menti shape and the anterior region of the mandible were used to predict the sex of the skull with above 80% accuracy in a South African study on mandibles [16]. The most accurate indicator robustness of the mandible with accuracy of 70% [17] There are many studies done in order to prove the sexual dimorphism of the mandible.one of such studies was done by Henneberg [11], where he described posterior ramus flexure as a prominent feature to determine the sex of the mandible.then studies where done on sex of mandible by Jayakaran.F [12] in mandibles of Karnataka. Then

5 Franklin.D [13] in 2008 did a study on South African mandibles and later in 2009 Ongkana.N [14] did a study on mandibles of Thai origin. In Jayakaran s study [12] on 207 mandibles it was found that mean of the Bicondylar length in males was found to be ± 0.53cm and in females was found to be ±0.53cm (table 5 )and mean of Bigonial length in males was found to be 9.38 ± 0.54cm and In females was 8.71 ± 0.48cm (table 6) but in our current study on 40 mandibles it was found that mean of the Bicondylar width to be ± 0.51cm in males and ± 0.55cm in females and mean of Bigonial width was observed to be 9.40 ± 0.55cm in males and 8.35 ± 0.29cm in females. The results of present study is similar to older studies. [Table 5] In Franklin s study [13] 225 on mandibles of South African origin it was found that mean of the Bicondylar width in males was found to be ± 0.60cm and in females was found to be ± 0.58cm (table 5) and mean of Bigonial width in males was found to be 9.35 ± 0.57cm and In females was 8.70 ± 0.56cm (table 6) but in our current study on 40 mandibles it was found that mean of the Bicondylar width to be ± 0.51cm in males and ± 0.55cm in females and mean of Bigonial width was observed to be 9.40 ± 0.55cm in males and 8.35 ± 0.29cm in females. The results of present study is similar to older studies. [Table 6] In Ongkana s study [14] on 102 mandibles of Thai origin it was found that mean of the Bicondylar length in males was found to be ± 0.63cm and in females was found to be ± 0.59cm (table 5) and mean of Bigonial length in males was found to be 9.68 ± 0.77cm and In females was 8.97 ± 0.59cm (table 6)but in our current study on 40 mandibles it was found that mean of the Bicondylar width to be ± 0.51cm in males and ± 0.55cm in females and mean of Bigonial width was observed to be 9.40 ± 0.55cm in males and 8.35 ± 0.29cm in females. The results of present study is similar to older studies. In Singh s study [15] on 50 mandibles of North Indian origin it was found that mean of the Bicondylar length in males was found to be ± 0.68cm and in females was found to be ± 0.58cm( table 5) and mean of Bigonial length in males was found to be 9.62 ± 0.72 cm and In females was 8.43±0.47cm(table 6) but in our current study on 40 mandibles it was found that mean of the Bicondylar width to be ± 0.51cm in males and ± 0.55cm in females and mean of Bigonial width was observed to be 9.40 ± 0.55cm in males and 8.35 ± 0.29cm in females. The results of present study is similar to older studies. In the present study of 40 mandibles of the south Indian origin it was found that mean of the Bicondylar length in males was found to be ± 0.51cm and in females was found to be ± 0.49cm and mean of Bigonial length in males was found to be 9.40 ± 0.55cm and In females was 8.35 ± 0.29cm. In the present study, the Mandibular length, the length between anterior chin and the straight line projection in the angle of the posterior sides of ramus was measured and was found to be a mean of 7.2 ± 0.54cm in females and 7.84 ± 0.45cm in males So present study observed a mean which is similar to older studies.identification of sex of the individual through bones is a critical problem in forensic studies. This study was conducted on dry skulls of South Indian origin on which 7 parameters were taken into account in which 4 are morphological parameters namely Symphysis menti, muscular marking, posterior ramus flexure, and Gonion flare and 3 are metric parameters namely Bigonial length

6 Bicondylar length and mandibular length where observed. These factors are proven to be statistically significant with help of SPSS software with the help of independent t test. CONCLUSION: Determination of sex from the skeletal remains is of great importance in medicolegal issues and forensic studies. As non-metric methods of sex determination in bones depends on the experts in forensic studies. This present study has utilised different morphological and metric parameters like Bicondylar length, Bigonial length and gonion flare for sex determination in dry skulls of South Indian origin. These factors metric parameters along with non-metric parameters help in sex determination in forensic studies as a tool for identifying an individual as it proves to be a genuine evidence for medicolegal issues and other related issues. ACKNOWLEDGEMENT: With sincere gratitude, we acknowledge the staff members of anatomy department, Dr.M.S.Thenmozhi (HOD of Anatomy department, Saveetha Dental College) and Saveetha Dental College for the extended support. REFERANCES: [1] Kim,H.J., Lee,H.Y., Chung,H.I., Cha,I.H., and Yi, CK. (1997) Mandibular Anatomy Related to Sagittal Split Ramus Osteotomy in Koreans. Yonsei Medical journal, 38, [2] Giles, E. (1964) Sex Determination by Discriminate Function Analysis of the Mandible. American Journal of Physical Anthropology, 22, [3] Ongkana, N. and Sudwan, P. (2009) Gender Difference in Thai Mandibles Using Metric Analysis. Chiang Mai Medical Journal, 48, [4] Aitchison, J. (1963) Sex Differences in Teeth, Jaws, and Skulls. Dental practice, 15,52-57 [5] Ongkana, N. and Sudwan, P. (2010) Morphologic Indicators of Sex in Thai Mandibles Using Metric Analysis. Chiang Mai Medical Journal, 49, [6] Shamout, A.R., Ammoush, M., Alrbata, R. and Habahbah, A.A. (2012) Age and Gender Differences in Gonial Angle, Ramus Height and Bigonial width in Dentate Subjects. Pakistan Oral & Dental Journal, 32, [7] Baydas, B., Yavuz, I.M., Bolukbasi, B. and Ceylan, I. (2004) an Investigation of Maxillary and Mandibular Morphology in Different Overjet Groups. Australian Orthodontic Journal, 32, [8] Heereshchandra and Malaviya, G. (1972) The Sexing of Human Mandible. Journal of the Indian Academy of Forensic Sciences, II, 7 [9] Devi, R., Arna, N., Manjunath, K.Y. and Balasubramanyam, M. (2003) Incidence of Morphological Variants of Mandibular Lingula. Indian Journal of Dental Research, 14, [10] Martin, E.S. (1936) A Study of an Egyptian Series of Mandibles with Special Reference to Mathematical Methods of Sexing. Biometrica, 28,

7 [11] Loth SR, Henneberg M. (1996) Mandibular ramus flexure: A New Morphological Indicator of Sexual Dimorphism in Human Skeleton. Am J Phys Anthropol, 99(3), [12] Jayakaran, F., Rajangam, S., Janakiram, S. and Thomas, I.M. (2000) Sexing of the Mandible. Anatomica Karnataka, 1, [13] Franklin, D., O Higgins, P. and Oxnard, C.E. (2008) Discriminant Function Sexing of the Mandible of Indigenous South Africans. Forensic Science International, 179, [14] Ongkana, N. and Sudwan, P. (2009) Gender Difference in Thai Mandibles Using Metric Analysis. Chiang Mai Medical Journal, 48, [15] Singh, R., Mishra, S.R.., Sushobhana, Passey, J., Kumar, P., Singh, S., Sinha P. and Gupta, S. (2015) Sexual Dimorphism in Adult Human Mandible of North Indian Origin. Forensic Medicine and Anatomy Research, 3, [16] Loth, S.R. and Hennberg, M. (1998) Mandibular Ramus Flexure is a Good Indicator of Sexual Dimorphism. American Journal of Physical Anthropology, 105, [17] Indrayana, N.S., Glinka, J. and Mieke, S. (1998) Mandibular Ramus Flexure in an Indonesian population. American Journal of Physical Anthropology, 105, TABLES AND FIGURES FEATURES No Of Mandibles : 50 Male Female SYMPHASIS MENTI Square Rounded GONIAL FLARE Everted Inverted MUSCULAR MARKINGS Prominent Not prominent NO OF BONES RAMUS FLEXURE Present Absent [Table 1]: Observations done on the basis of morphological parameters. MEASUREMENTS MALE FEMALE NO OF BONES RANGE 10.63cm 11.65cm 9.61cm 10.59cm MEAN (cm) 11.14cm 10.10cm STANDARD DEVIATION 0.51cm 0.49cm [Table 2]: Bicondylar length measured in 40 mandibles after exclusion MEASUREMENTS MALE FEMALE NO OF BONES RANGE 8.85cm -9.95cm 8.06cm 8.64cm MEAN (cm) 9.40cm 8.35cm STANDARD DEVIATION 0.55cm 0.29cm [Table 3]: Bigonial length measured in 40 mandibles after exclusion

8 MEASUREMENTS MALE FEMALE NO OF BONE RANGE 7.39cm -8.29cm 6.66cm 7.74cm MEAN 7.84cm 7.20cm STANDARD DEVIATION 0.45cm 0.54cm [Table 4]: Mandibular length measured in 40 skulls after exclusion AUTHORS FEMALE MALE Jayakaran et al. (2000) 10.77cm ± 0.53cm 11.26cm ± 0.53cm Franklin et al. (2007) 10.86cm ± 0.58cm 11.36cm ± 0.60cm Ongkana et al. (2009) 11.61cm ± 0.59cm 12.38cm ± 0.63cm Vinay et al. (2013) 10.82cm ± 0.70cm 11.34cm ± 0.55cm Present Study 10.10cm ± 0.49cm 11.14cm ± 0.51cm [Table 5]: Comparison of data of Bicondylar breadth measured in present study with older studies AUTHORS FEMALE MALES Jayakaran et al. (2000) 8.71cm ± 0.48cm 9.38cm ± 0.54cm Franklin et al. (2007) 8.70cm ± 0.56cm 9.35cm ± 0.57cm Ongkana et al. (2009) 8.97cm ± 0.59cm 9.68cm ± 0.77cm Vinay et al. (2013) 8.74cm ± 0.54cm 9.45cm ± 0.53cm Present Study 8.35cm ± 0.29cm 9.40cm ± 0.55cm [Table 6]: Comparison of data of Bigonial breadth measured in present study with older studies IMAGES:

9 [Image 1]: Measuring of Bicondylar length [Image 2]: Measuring of Bigonial length