Original communication Third molar development by measurements of open apices in an Italian sample of living subjects Stefano De Luca a, b, * , Andrea Pacifici b, c , Luciano Pacifici b, c , Antonella Polimeni c , Sara Giulia Fischetto c , Luz Andrea Velandia Palacio b , Stefano Vanin d , Roberto Cameriere b a Departamento de Antropologia, Facultad de Ciencias Sociales y Jurídicas, Universidad de Tarapac a, Arica, Chile b AgEstimation Project, Institute of Legal Medicine, University of Macerata, Macerata, Italy c Department of Oral and Maxillofacial Sciences, Sapienza University of Rome, Italy d School of Applied Science, University of Huddersfield, Queensgate, Huddersfield HD1 3DH, UK article info Article history: Received 15 July 2015 Received in revised form 30 October 2015 Accepted 14 November 2015 Available online 30 November 2015 Keywords: Forensic sciences Age estimation Dental development Third molar index Italy abstract The aim of this study is to analyse the age-predicting performance of third molar index (I 3M ) in dental age estimation. A multiple regression analysis was developed with chronological age as the independent variable. In order to investigate the relationship between the I 3M and chronological age, the standard deviation and relative error were examined. Digitalized orthopantomographs (OPTs) of 975 Italian healthy subjects (531 female and 444 male), aged between 9 and 22 years, were studied. Third molar development was determined according to Cameriere et al. (2008). Analysis of covariance (ANCOVA) was applied to study the interaction between I 3M and the gender. The difference between age and third molar index (I 3M ) was tested with Pearson's correlation coefficient. The I 3M, the age and the gender of the subjects were used as predictive variable for age estimation. The small F-value for the gender (F ¼ 0.042, p ¼ 0.837) reveals that this factor does not affect the growth of the third molar. Adjusted R 2 (AdjR 2 ) was used as parameter to define the best fitting function. All the regression models (linear, exponential, and polynomial) showed a similar AdjR 2 . The polynomial (2nd order) fitting explains about the 78% of the total variance and do not add any relevant clinical information to the age estimation process from the third molar. The standard deviation and relative error increase with the age. The I 3M has its minimum in the younger group of studied individuals and its maximum in the oldest ones, indicating that its pre- cision and reliability decrease with the age. © 2015 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved. 1. Introduction Assessing dental age is important to know whether children and youths are growing properly and is especially useful in orthodon- tics, paediatric dentistry, forensics, and anthropology. 2 For pedo- dontist and orthodontist, knowing child's developmental status is especially significant in diagnosis and treatment planning. 3 In forensic field, dental age is mostly used in resolving issues regarding immigration and prosecution in the criminal and civil courts. 4 However, a particular limitation of dental development stan- dards is that the reliability of age estimation is not uniform from birth to adulthood. Age estimation for children up until the age of 14e15 years can be reliably assessed using both skeletal and dental development. 5 In fact, up to this time, age estimation is more rewarding and accurate. As a person grows beyond these years, developmental variability increases, thus making age estimations relative imprecise during adolescence. 5 Toward the end of human skeletal growth and development, only a few age-dependent fea- tures can be evaluated by morphological methods. 6 The third molar is the latest tooth to initiate and complete development and therefore is the last available dental morphologic predicator of age. 7,8 The possibilities of using this tooth for assessing age are limited by the duration of its development. The third molar is more variable than for all the other maturity markers, such as the clavicle and the knee. 9 In addition, the third molar is * Corresponding author. Departamento de Antropologia, Facultad de Ciencias Sociales y Jurídicas, Universidad de Tarapac a, Arica, Chile. Tel.: þ56 965410685. E-mail address: sluca@ugr.es (S. De Luca). Contents lists available at ScienceDirect Journal of Forensic and Legal Medicine journal homepage: www.elsevier.com/locate/jflm http://dx.doi.org/10.1016/j.jflm.2015.11.007 1752-928X/© 2015 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved. Journal of Forensic and Legal Medicine 38 (2016) 36e42