American Journal of Medical and Biological Research, 2018, Vol. 6, No. 1, 1-6 Available online at http://pubs.sciepub.com/ajmbr/6/1/1 ©Science and Education Publishing DOI:10.12691/ajmbr-6-1-1 Assessing Ramus Dimorphism of Jordanian Mandibles Wala M Amin * Faculty of Dentistry, University of Jordan, Amman, Jordan *Corresponding author: wami@ju.edu.jo, walaamin@gmail.com Abstract This investigation deals with descriptively examining the mandibular rami of young Jordanian adults for the presence or the lack of it of a flexure at the posterior border of a ramus; and evaluating the role of ramus flexure in sex identification. Three-dimensional (3D) rendered Cone Beam Computed Tomography (CBCT) images of a normative sample comprising 270 images were selected, of which 147 belonged to male patients and 123 images to females. Strict exclusion criteria were applied in selecting images. Each image was examined for the presence of a flexure on the posterior border of the ramus, which was carefully delineated and the occlusal plane marked, guided by the height of cusp tips of the mandibular molars. The results indicated that the ramus flexure method of sex prediction was more accurately diagnostic for females (85.1%), than for males (78.9%); this gave rise to an overall diagnostic accuracy of 82.2% which is below the reported 90.6-99.0% by Loth & Henneberg. Our results, however, agreed with the reported findings of other researchers. In conclusion, ramus flexure provides an acceptable predictive accuracy and could be considered as a supplementary rather than a definitive mean of sex determination. Keywords: sex dimorphism, ramus flexure, morphologic trait, predictive accuracy, forensic fossils, skeletal remains Cite This Article: Wala M Amin, “Assessing Ramus Dimorphism of Jordanian Mandibles.” American Journal of Medical and Biological Research, vol. 6, no. 1 (2018): 1-6. doi: 10.12691/ajmbr-6-1-1. 1. Introduction Sex determination of unknown skeletal remains is the most challenging, among other targets, such as, identification of age, stature and ethnic origin. The pelvic bone and mandible reflect anatomical differences between male and female; therefore they were used in many past studies, which centered on morphological differences that arise from genetically sex-linked growth and development [1,2,3]. The mandible was used in most studies since it is one of the most durable bones and persists in a well preserved state longer than other bones. There have been many publications dealing with sexual differentiation according to morphological traits of the mandible. In some early reports, Loth and Henneberg [4,5,6,7] described a flexure in the posterior border of the mandibular ramus that was present in males’, but absent in females’ mandibles, and used the flexure in sex determination. They claimed sexing accuracy ranging from 90.6% to 99% that the ramus is flexed in males at the same level of the occlusal plane whereas in females the ramus border is either straight or flexed near the neck of condyle or in association with gonial prominence. In a counter argument, other researchers reported that the association between ramus flexure and sex was weak; and that Loth and Henneberg’s method was based on a trait that, they believed, cannot be reliably or consistently identified, thus, threw doubt on the accuracy and reliability of that method of sex identification [8,9,10]. They reported that although the ramus flexure seemed to be greater and more constant in males, the overlap between the shapes of male and female rami was too substantial to make the ramus flexure method a valid means of sex determination. Some researchers tried Loth and Henneberg method of sex identification on their sample and reported that about two-thirds of the Orthopantomographic (OPT) images of females were correctly sexed, whereas the prediction accuracy was less than 50% for males [11,12]. Those were much lower than the success rates reported by Loth and Henneberg, which raised suspicion on the predictive accuracy and reliability of mandibular ramus flexure as a morphological indicator of sex. The literature contains varying reports, some argued for and some against the ramus flexure method of sex identification. Those researchers who supported the method had tried it on their test sample and claimed an overall prediction accuracy rate of 83% [13], whereas, those who were not in favor of the method reported a relatively lower prediction rate (76%) [14]. The general belief of all reported studies that using this sex dimorphic predictor may not attain a high confidence level, and, therefore, it should be coupled with other indicators of sex dimorphism. Many past studies were carried out directly on dry mandibles. However, it is probably, because of the difficulty involved in getting access to dry skulls in the numbers required by the studies, researchers sought alternatives to dry skulls and employed “OPT” images of their patients’ mandibles in their analyses [15]. However, the alternative method, i. e., “OPT” being a two-dimensional (2D) diagnostic rendering from a three-dimensional (3D) structure, it is bound to yield images subject to projection, landmark identification, and measurement errors. Attempts to develop a 3D imaging technique to improve diagnosis has intensified during the late 1990s, and culminated during