TECHNICAL NOTE Patrick W. Thevissen, 1 D.D.S.; Pisha Pittayapat, 2 D.D.S.; Steffen Fieuws, 3 M.Sc., Ph.D.; and Guy Willems, 1 D.D.S., Ph.D. Estimating Age of Majority on Third Molars Developmental Stages in Young Adults from Thailand Using a Modified Scoring Technique* ABSTRACT: The aim of this study was to achieve a referral database for dental age estimation of unaccompanied minors of Thai nationality. A total of 1199 orthopantomograms were collected from original Thai women and men equally divided in age categories between 15 and 24 years. On the radiographs, the developmental stage of the third molars was scored applying a modified scoring technique. Inter- and intra-observer reliabilities were tested using kappa statistics. Correlation between the scores of all four wisdom teeth and left–right symmetry were evaluated with Pearson’s cor- relation coefficient. Student’s t-test on asymmetry was performed and regression formulas were calculated. The present database was the first to assemble third molar developmental scores on radiographs of Thai individuals and provides more appropriate dental age estimation of unaccompanied Thai minors. Future research on similar databases of different nationalities worldwide may expose ethnical influences on dental development. KEYWORDS: forensic science, forensic odontology, age estimation, third molar development, ethnicity, Thailand Dental age estimating methods employed in forensic odontology (1,2) are based on the changes in development (3–7), morphology (8–13), and biochemical (14–16) structure of teeth. Estimating the age of individuals or victims narrows the search for antemortem data during identification procedures of unknown remains (17,18), helps in establishing the difference between the juvenile and adult status of an individual in law cases (19–21), and aids persons with- out a birth certificate finding out their presumed age (22). Nowadays the judicial need to classify human beings lacking age information into the adult or juvenile group increases continually. Dental age estimation methods based on the analysis of the radiological deter- mined developmental stages of third molars are the only tooth formation approaches for the judgment of this specific lifetime per- iod (6,23). Although several population-specific dental age estima- tion researches on third molar development have been carried out, the collection of referral databases consisting of orthopantomograms of youngsters from the same national origin is strongly needed to ameliorate the accuracy of dental age estimation procedures. For consideration as a valuable age estimation database, it needs to con- tain large-sized samples of individuals with the same national or ethnic origin (24,25). The dental age estimation results obtained based on these databases have to be compared and integrated with the results collected by other methods, such as clinical observation (19), psycho-social age approach (26), evaluation of changes in sec- ondary sex characteristics (27), epiphysial fusion of hand-wrist and sternoclavicular bones (28–31), changes in pubic symphysis (32) and anterior iliac crest (33), fusion of cranial sutures (34,35), cranial size changes (36), and occlusal tooth wear (11). The aim of the present paper was the establishment of a radio- logical database of orthopantomograms from young adults with ori- ginal Thai nationality so as to obtain regression formulas for age estimation of Thai individuals. Materials and Methods In this retrospective study, 1199 orthopantomograms were collected and selected at the Faculty of Dentistry, at the Chul- alongkorn University (Bangkok, Thailand). The radiographs were digitally generated on a Kodak 8000C Digital Panoramic and Cephalometric System (Kodak Dental Systems, Atlanta, GA) and stored as TIF files in the period from 2005 to 2007. All the X-rays were captured from persons of Thai nationality and mongoloid eth- nicity, with known chronological age at the moment of radiologic exposure. During the selection, only orthopantomograms of individ- uals with no medical history, no visible dental pathology on the radiographs, and at least one upper and one lower third molar pres- ent, were retained. The selected group was split into 613 women and 586 men, with each an age spread older than 15 years and younger than 24 years (Table 1). All of the 4530 third molars visible on the orthopantomograms (Table 2) were observed and classified by the 10-point develop- mental scoring system as proposed by Gleiser and Hunt (37) and modified by Kçhler et al. (38) (Fig. 1), and if necessary imported into Adobe Ò Photoshop Ò (Adobe Systems Incorporated, San JosØ, 1 Department of Dentistry, Oral Pathology and Maxillo-Facial Surgery, Section Forensic Odontology, Katholieke Universiteit Leuven, Leuven, B 3000, Belgium. 2 Department of Dentistry, Section Radiology, Chulalongkorn University, Bangkok, 10330, Thailand. 3 Centre of Biostatistics, Katholieke Universiteit Leuven, Leuven, B 3000, Belgium. *Presented at the 60th Annual Meeting of the American Academy of Forensic Sciences, February 18–23, 2008, in Atlanta, GA. Received 12 Mar. 2008; and in revised form 22 April 2008; accepted 26 April 2008. J Forensic Sci, March 2009, Vol. 54, No. 2 doi: 10.1111/j.1556-4029.2008.00961.x Available online at: www.blackwell-synergy.com 428 Ó 2009 American Academy of Forensic Sciences