Forensic Anthropology Population Data Odontometric sex variation in Malaysians with application to sex prediction Mohd F. Khamis a,b, *, Jane A. Taylor a,c , Shan N. Malik b , Grant C. Townsend a a School of Dentistry, The University of Adelaide, SA 5005, Australia b School of Dental Sciences, Health Campus, Universiti Sains Malaysia, 16150 Kota Bharu, Malaysia c School of Health Sciences, Faculty of Health, The University of Newcastle, University Drive, Callaghan, NSW 2308, Australia 1. Introduction Odontometric differences between males and females are reported to be only around 3–4% in magnitude [1] but several researchers have shown promising applications for sex identifica- tion in archaeological and forensic situations using a combination of tooth sizes, with the success rates ranging from 71% to 93% [2– 8]. Sex prediction has also been successful, with a probability of up to 80–90%, by utilizing a combination of tooth sizes and root lengths [9], by using the ratio between canine width and inter- canine distance [10], by obtaining diagonal tooth measurements [11] or by using a combination of incisor and canine indices [12]. Knowing the sex of an individual is an important step in reconstructing identity. This information is crucial in searching for potential ante-mortem evidence for the comparative identification process. Odontometric methods are obviously only applied in cases where the sex organs, other secondary sexual characteristics, and deoxyribonucleic acid are not available for analysis. The physical robustness of teeth, which can withstand decomposition processes and adverse environmental conditions, for instance heat up to 1000 8C [13] and submersion in water [14], is an advantage for forensic investigations. Currently, there are no reference studies for sex prediction using odontometric data in the Malaysian population. According to the Malaysian census 2010, the Malays, Chinese and Tamils are the majority ethnic groups in Malaysia [15]. From an historical perspective, the Malaysian Chinese came mainly from Southern China while the Malaysian Tamils came mainly from Southern India [16]. Since there is obvious population variation in the pattern and magnitude of sexual dimorphism [17–19], this study aims to quantify success rates of sex prediction models for the Malaysian population as a whole and also for each of the ethnic groups. In addition, the predictive models developed should be suitable to be used in real forensic situations. Forensic Science International 234 (2014) 183.e1–183.e7 A R T I C L E I N F O Article history: Received 14 September 2012 Received in revised form 17 July 2013 Accepted 16 September 2013 Available online 25 September 2013 Keywords: Odontometric profile Malaysian Sex prediction Forensic Anthropology Population Data Tooth size A B S T R A C T Information about the sex of individuals is important for human identification. This study was conducted to quantify classification rates of sex prediction models for Malaysians using odontometric profiles. Mesiodistal (MD) and buccolingual (BL) crown dimensions of the permanent dentition were studied in 400 young adult Malaysians, giving a total of 28 tooth size variables. The sample consisted of three major ethnic groups, the Malays, Chinese and Tamils, since the aim was to assess sex dimorphism in Malaysians as a whole. Results showed that the mesiodistal diameter of the lower canine was the most sexually dimorphic dimension in Malaysian Malays and Tamils. Univariate analyses showed that the magnitude and pattern of sex dimorphism varies between these three ethnic groups, with Malaysian Chinese and Tamils being more dimorphic than the Malaysian Malays. Stepwise discriminant functions were generated bearing in mind their application in practical forensic situations. The range of classification rates was from 70.2% to 78.5% for the composite Malaysian group, and 83.8%, 77.9%, 72.4% for Malaysian Chinese, Malays and Tamils, respectively. The ‘Area Under the Receiver Operating Characteristic Curve statistics’ indicated good classification rates for three prediction models obtained using a combination of all tooth size variables, mandibular teeth, and mesiodistal dimensions in the composite Malaysian group, and for all tooth size variables in each ethnic group. The present study provides strong support for the value of odontometry as an adjunct scientific method for sex prediction in human identification. ß 2013 Elsevier Ireland Ltd. All rights reserved. * Corresponding author at: School of Dental Sciences, Health Campus, Universiti Sains Malaysia, 16150 Kota Bharu, Malaysia. Tel.: +60 9 7675660; fax: +60 9 7642026. E-mail addresses: fadhli@kb.usm.my, dr_kingg2000@yahoo.com.au (M.F. Kha- mis), jane.taylor@newcastle.edu.au (J.A. Taylor), shan@kk.usm.my (S.N. Malik), grant.townsend@adelaide.edu.au (G.C. Townsend). Contents lists available at ScienceDirect Forensic Science International jou r nal h o mep age: w ww.els evier .co m/lo c ate/fo r sc iin t 0379-0738/$ – see front matter ß 2013 Elsevier Ireland Ltd. All rights reserved. http://dx.doi.org/10.1016/j.forsciint.2013.09.019