published_or_final_version / Paediatric Dentistry / Master / Master of Dental Surgery

Age assessment which is an integral part of forensic and clinical practice when assessed using the extent of dental development has proven to be more accurate than other methods. Variations in dental development have necessitated the construction of ethnic specific reference datasets (RDS) to ensure accurate age assessments. Age estimated from ethnically different RDS in southern Chinese subjects has been shown to be inaccurate. A systematic review and meta-analysis from the most commonly used French-Canadian dataset revealed consistent over-estimations of age of global population groups, inferring the need for population specific RDS. A study which compared a group of 400 five years old children born in the 1980s and the 2000s demonstrated that children born in recent decades have more advanced dental development. Hence, only the most recent samples were included in the construction of a RDS for southern Chinese using dental panoramic radiographs of 2306 subjects. The reference dataset was subsequently validated on 484 subjects of southern Chinese origin by conducting dental age assessments (DAA) using un-weighted and weighted methods of dental age calculations. Paired t-test demonstrated that all methods of assessments were able to accurately estimate the age (p>0.05). The overall age differences ranged from -0.01 to 0.11 years for males and -0.03 to 0.10 years for females respectively. In addition, to test the accuracy of different ethnic datasets, 266 southern Chinese subjects for whom age had been estimated using the UK Caucasian and French-Canadian datasets were re-scored using the southern Chinese RDS. The latter was able to estimate the age of 80% of the subjects within a range of 12 months and the importance of population specific reference standards was elucidated. The validated southern Chinese RDS on dental development can thus be used to estimate the age of children and young adults of southern Chinese origin. This RDS was also tested for applicability on the records of 953 subject obtained from Japan, Thailand and Philippines. A similar method of validation was conducted and the southern Chinese RDS estimated the age of Thai males, Filipino and Japanese subjects with a reasonable degree of accuracy. The genetic similarity between the southern Han Chinese and the other East Asian population groups may account for the obtained accuracy. The secular trend study was the first of its kind study in Asia that demonstrated advanced dental maturation in children born in recent decades. Natural calamities that strike East Asia leave thousands of people missing. In those circumstances, dental age assessment using the southern Chinese RDS would help in the process of identifying deceased victims. Furthermore, only half of the children in the world below the age of five years are registered; thus the need for determining age is of foremost importance to safeguard them against age specific crimes. Methods of establishing reference datasets and conducting accurate age assessments that have been investigated and tested in this study indicate that the methodology can be applied to any ethnic population group in the world. / published_or_final_version / Paediatric Dentistry / Doctoral / Doctor of Philosophy

published_or_final_version / Dentistry / Doctoral / Doctor of Philosophy