ORIGINAL ARTICLE Age estimation in Turkish children and young adolescents using fourth cervical vertebra Ayse Gulsahi 1 & Sevi Burçak Çehreli 2,3 & Ivan Galić 4,5 & Luigi Ferrante 6 & Roberto Cameriere 4 Received: 30 May 2019 /Accepted: 2 January 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020 Abstract This study aimed to test radiographic projections of the posterior and anterior sides of the C4 vertebral body for age estimation in a cross-sectional sample of Turkish children and adolescents from the Baskent University Faculty of Dentistry. A sample of 232 x-rays from individuals aged between 5 and 15 years (101 boys and 131 girls) was analysed to investigate the correlation of age and changes in the projection ratio of the anterior and posterior sides of the body of the fourth cervical vertebra (Vba) in lateral cephalograms. The Normal Bayesian Calibration (NBC) model for age estimation was used to assess the relationship between Vba and age. The intra-observer repeatability and inter-observer agreement were 0.95 and 0.94, respectively. Age distribution gradually increased as Vba increased up to 14 years in both sexes. The difference between chronological and estimated ages did not increase with the increase in age. Calibration distributions of the dataset by the evaluation of Vba suggested mean absolute errors (MAEs) of 0.879 years and 0.906 years (mean interquartile ranges (MIQRs) 1.290 and 1.435 years)) in boys and girls, respectively. The biases of the estimates (β ERR ) were 0.013 and 0.027 for boys and girls, respectively. In conclusion, the NBC method on Vba variable appears to be suitable for age estimation in Turkish children and adolescents. Keywords Ageestimation . NormalBayesianCalibration model . Fourthcervicalvertebra . Forensicanthropologypopulationdata Age estimation is a requisite for penal responsibility and cul- pability in the judicial systems in the world [1–3]. A different skeletal system in the human body changes in correlation with the growth and development of a person. Growth can be iden- tified by chronological age, sexual maturation, body height, weight, dental development, and skeletal development [4–6]. Growth and development primarily refer to the skeleton, and radiographic analysis to estimate skeletal maturity is a widely accepted procedure [2, 4, 7–9]. Different legal and criminal procedures depend on the age of the individuals in investigation or prosecution, so the infor- mation of his or her real age is mandatory. Forensic age esti- mation methods combine all relevant indicators and use evidence-based methods to estimate chronological age [8, 10, 11]. The oldest and most widely used assessment method for skeletal maturation is the analysis of hand and wrist radio- graphs, showing the gradual appearance of carpal bones and * Ivan Galić igalic@mefst.hr Ayse Gulsahi agulsahi@baskent.edu.tr Sevi Burçak Çehreli bcehreli@eul.edu.tr Luigi Ferrante l.ferrante@staff.univpm.it Roberto Cameriere agestimationproject@gmail.com 1 Department of Dentomaxillofacial Radiology, Faculty of Dentistry, Baskent University, Ankara, Turkey 2 Pediatric Dentist, Specialist, Ankara, Turkey 3 Faculty of Dentistry, European University of Lefke, Lefke, Northern Cyprus TR-10 Mersin, Turkey 4 AgEstimation Project, Macerata, Italy 5 Department of Oral Surgery, University of Split School of Medicine and University Hospital Centre, Split, Croatia 6 Center of Epidemiology, Biostatistics and Medical Information Technology, Department of Biomedical Science and Public Health, Polytechnic University of Marche, Ancona, Italy International Journal of Legal Medicine https://doi.org/10.1007/s00414-020-02246-8