CAPT RISHI POKHRELCOL RAJAN BHATNAGARCOL SUSHIL KUMAR
INTRODUCTION Determination of sex from skeletal remains – initial step in determination of identity Human mandible - among the strongest bones - significant sexual dimorphism Multivariate Discriminant Functional Analysis (MDFA) – best among metric methods. Population: Marathwada region of Maharashtra.
AIMS & OBJECTIVES To test sexual dimorphism in mandibles of population under study. To identify parameters of mandible that show maximum sexual dimorphism To determine population specific cut off point and constants for MDFA. To test the accuracy of MDFA.
MATERIALS & METHODS Cross sectional, observational study Adult mandibles of known sex from Anatomy department, GMC, Aurangabad. Sample size : 103 Males: 77 Female, 26 Females : 26 Male, 7 Exclusion criteria 7 Incomplete Gross asymmetry Extreme of ages
PARAMETERS USEDParameter (Midline) Abbn. Parameter (Bilateral) Abbn.Symphyseal height ID GN Height of mandibular body HTBicondylar breadth CDL CDL Mandibular thickness at mental MB foramenBigonial breadth GO GO Minimum ramus breadth MnRbMandibular length ML Maximum ramus breadth MxRBIntermolar distance IMD Mandibular or gonial angle AIntercanine distance ICDArch perimeter AP Units mm, degree, cms
Parameter b STEP 1: MDFA ID GN -0.037 Multivariate discriminant function HT 0.076 f (x) = b0 + b1x1 + b2x2 + b3x3 + --------- + b13x13. MB 0.267 GO GO -0.050 Where, f (x) : MDFA score CDL CDL 0.041 b0 : constant (-7.704) Mn RB -0.185 Mx RB -0109 b1 to b1 : raw coefficients Mx RH 0.053 x1 to x13 : variables values ML -0.015 f(x) at group centroid for males = - 0. 556 A 0.101 IMD 0.053 f(x) value at group centroids for females = 1.648 ICD 0.033 Demarcation point = 1.09 AP -0.301
STEP 2: STEPWISE MDFA A combination of MnRB and A was found to be best among all. The function f (y) = b0 + b1 (MnRB) + b2 (A) b0 = 3.755 b1 = 0.202 b2 = - 0.089 f(x) at group centroid for males = 0.435 f(x) value at group centroids for females = -1.288 Demarcation point = - 0.9628
FUNCTION FOR MDFA f(x) = (- 0.704) + (-0.037) ID GN + (0.076) HT + MB (0.267) +GO GO (-0.050) + CDL CDL (0.041) + MnRB (-0.185) + MxRB( -0109) + MxRH (0.053)+ ML (-0.015) + A (0.101) + IMD (0.053) + ICD (0.033) + AP (-0.301) f(x) > 1.09, the mandible belongs to female f(x) < 1.09, the mandible belongs to male Accuracy : 90.3%
FUNCTION FOR S - MDFA f(y) = 3.744 + (0.202) MnRB + (-0.089) A If, f(y) > - 0.9628 the mandible belongs to male and if f(y) < - 0.9628, the mandible belongs to female Accuracy: 85.4%
DISCUSSION Author (s) with population No of Parameters Accuracy % used(Hanihara, 1959), Japan 4 88.6(Giles, 1964), USA 3–8 82.0 – 88.0(Potsch-Schneider et al., 1985), Germany 17 71.6 - 81.7(Steyn & Iscan, 1998), South Africa 5 81.5(Barthélémy et al., 1999), France 2-7 87.3(Muñoz et al., 2001), Spain 1 - 14 78.3 - 88.7(Vodanović et al., 2006), Croatia 1-9 74.12 – 92.06(Simona et al., 2007), Romania 5-7 86.0(Saini et al., 2011), Varanasi, India 1-5 60.3 - 80.2Current study, 2012, Maharashtra, 2 - 13 85.4 – 90.3India
Saini et al, 2011, Indian Population (Varanasi) Sample size : Total 116, Male 92, Female 24 Functions and Variables Avg. Acc. %Max. ramus br. + min. Ramus. br. + condylar ht. + projective ht. + 80.2coronoid ht.Max. ramus br. + min. ramus br. + coronoid ht. 80.2Condylar ht + projective ht + coronoid ht. 76.7Coronoid ht. 74.1Condylar ht. 72.4Projective ht. 68.1Max ramus br. 62.1Min ramus br. 60.3 Our study Maximum 90.3% Minimum 85.4%
CONCLUSIONS Mandibles of population under study show sexual dimorphism. MnRB and A show maximum sexual dimorphism. Population specific coefficients, constants and demarcation points for MDFA are derived.Accuracy of sexing is comparable to other populations.