Dental maturity, expressed as dental age(DA), plays a vital role in forensic medicine andclinical dentistry.1-3 When a living person with a dubious chronological age(CA) certificate orclinical doctors need to understand dental maturity for the succeeding diagnosis andtreatment, dental age becomes a more critical issue to provide some valuable information.2Knowledge of the age of living individuals without valid documents may need to clarify legalquestions concerning the imputability of juvenile or young adult delinquents, pension claims ofolder individuals or requests for political shelter4.Physiologic age can be estimated by somatic, sexual, skeletal and dental maturity. Dentalage estimation(DAE), as one of radiographic methods, has more advantages over othermethods. It is more reliable and less affected by the outer surroundings.5 More importantly, itis less destructive.6 DAE is deemed to be one of the best methods concerning feasible andconvenient.7Demirjian method, which was put forward in 1973 by Demirjian, has been widely applied asa radiographic method to testify accuracy of age assessment.8 Demirjian introduced themethod for DAE according the study of 2928 children (1446 boys and 1482 girls) of a French-Canadian population. A classification system based on eight calcification stages which*Manuscript (WITHOUT Author Details)Click here to view linked Referencesrepresented the ordinal of tooth development from calcification of the crown cusps to closureof the apex of the seven left permanent mandibular teeth was structured. The score of eachstage was assigned and the aggregate of the scores turned into the subject’s dental maturityscore(DMS). The acquired dental maturity score can be finally converted into dental ageaccording to the provided transformation tables.Considering the fact that Demirjian method was based on French-Canadian population,after testifying the applicability of Demirjian method in different regions and different ethnicpopulations, inconsistent study outcomes tended to reject the generality of Demirjian method.Some reported Demirjian method overestimated chronological age: Spain,9 Germany10,Tunisia11,India 12, 13, Botswana 14, Malaysia15, Northern Iran16, Southern Australia 17,Serbia18 ,France 19. Northeastern Turkey20, Western China21.On the other side, there areseveral underestimation statements: Tunisia11,Western China21and Northern China22.In 2001, Willems brought forward a new age estimation standard which simplified Demirjianmethod23. A different transform table helped dental maturity score directly convert into dentalage. Not only simplifying transformation steps, several reports also voiced Willems methodwere more accurate when compared with Demirjian method15, 18, 19, 24. Considering the scarcestudies of dental age assessment of Eastern Chinese regions22, 24, 25, current researchesconcentrated on Demirjian or Willems or other methods alone, or comparison of Demirjianand Willems method under 18 years old24, which is the threshold of adult in China , remainedrare. So the purpose of the study was to:1. Evaluate the accuracy of dental age using Demirjian and Willems method on EasternChinese 11-18-year-old children and adolescents.2. Amend Demirjian method to create ideal age prediction model to make it more accurate forEastern Chinese 11-18-year-old children and adolescents.