ORIGINAL ARTICLE Mandibular ramus length as an indicator of chronological age and sex Fernando Toledo de Oliveira & Mariana Quirino Silveira Soares & Viviane Almeida Sarmento & Cassia Maria Fischer Rubira & José Roberto Pereira Lauris & Izabel Regina Fischer Rubira-Bullen Received: 10 April 2014 /Accepted: 28 August 2014 # Springer-Verlag Berlin Heidelberg 2014 Abstract Age and sex estimation is crucial in forensic investigations, whether in legal situations that involve living people or to identify mortal remains. The aim of this study was to establish reference values in a Brazilian population to estimate age and sex by measuring the length of the mandibular ramus on lateral cephalometric radiographs, and to determine the probability that an individual being is 18 years or older, based on the results that were obtained. Two hundred and eighteen scanned lateral cephalograms of individuals between 6 and 20 years of age (101 males and 117 females) were mea- sured with reference to mandibular ramus length (the distance between Condylion superior (Cs) and Gonion (Go)) using ImageJ 1.41 software (NIH, Bethesda, MA, USA). The results showed that sexual dimorphism was not observed until 16 years and, based on the ramus length measurements in this sample, it is possible to predict sex with an accuracy of only 54 %. There was a positive correlation between age and ramus length (r = 0.90; p <0.001). From the linear regression analysis, one formula was derived; therefore, it was possible to calcu- late the individual’ s age, given his or her ramus length. The results showed that if an individual’ s ramus length is 7.0 cm or more, then there is an 81.25 % chance that the individual is 18 years old or older. In conclusion, the mandibular ramus length was not effective in discriminat- ing sex. Mandibular length is strongly related to chronological age and can be used to predict whether an individual is 18 years or older with high degree of ex- pected accuracy. Keywords Cephalometry . Radiography . Bone age measurement . Forensic science . Sex determination by skeleton Introduction Forensic anthropology employs human identification to qual- itatively and quantitatively study several characteristics that are different among individuals. These characteristics include the estimation of age, sex, ethnicity, height, distinguishing marks, and biotype [1, 2]. The success in identifying a person has ethical, legal, and criminal significance. Human identifi- cation is not only a prerequisite for individuals who are officially declared dead, but is also the basis for the investiga- tion of crimes, mass disasters, or war atrocities [3, 4]. Biological sex identification is one of the most important techniques that has been established in forensic science. Sex estimation is usually one of the first stages of identifying an adult skeleton (after identifying whether the remains are hu- man and of forensic relevance) [1, 5]. For juveniles, whose skeletons are immature, although there are reports that sex identification is possible using human skeletal remains (e.g., mandible and cranium) from an early age, a high level of sex dimorphism is not observed until puberty, which constitutes a significant problem in forensic anthropology [5–8]. An estimation of age is equally important as an auxiliary method of human identification [1]. One should nonetheless make a distinction between the age estimation of unidentified corpses and skeletons, and the age estimation of living people. In the case of bodies, the crucial factors are the quality and F. T. de Oliveira : M. Q. S. Soares : C. M. F. Rubira : J. R. P. Lauris : I. R. F. Rubira-Bullen (*) University of São Paulo, Bauru, SP, Brazil e-mail: izrubira@fob.usp.br V. A. Sarmento Federal University of Bahia, Salvador, Bahia, Brazil Int J Legal Med DOI 10.1007/s00414-014-1077-y