Forensic age estimation based on third molar eruption and development for Ugandan adolescents and young adults

Abstract

Background: Forensic age estimation is critical for the Ugandan setting due to the increasing crime rates in the country among juveniles as reported by the Uganda Annual Police Report of 2017. In addition, currently Uganda is a host to many refugees from its turbulent neighbors and many of the children who seek refuge lack legal documentation like birth certificates. Objectives: This study aimed at exploring the current practice of age estimation among adolescents and young adults undergoing criminal proceedings (Sub-study 1) and to develop dental age estimate tables using third molar eruption (Sub-study II) and development (Sub-study III) for the Ugandan adolescent and young adult population. Methods: Sub-study I This was a qualitative study that enrolled 17 police surgeons and other public and private health professionals working with the Police, who were directly involved in the age estimation process within five districts of Uganda. Key informant interviews were used to collect the data. The data were analysed manually using thematic analysis strategy. Sub-studies II & III These were cross sectional studies using quantitative methodologies. One thousand and twenty-five (1025) dental patients aged 10–22 years were recruited for the study. They were of Ugandan descent attending the Mulago Dental School Clinic at the Mulago National Referral Hospital between January and December 2017. Patient sociodemographic details, radiographic recordings using the OPG and proof of age using birth certificates, hospital discharge forms, baptism certificate and national ID were all captured. Descriptive statistics were used to get means, medians, minimum and maximum age per tooth eruption (Sub-study II) and development stage (Sub-study III). Student’s t tests were used to get difference between jaws and sex. Linear regression was used to generate probabilities and ROC curves were used to determine the performance of the tooth stages (Sub-study III). Results: Sub-study I showed that the legally mandated professionals to estimate age are medical officers, clinical officers and registered midwives. Circumstances requiring age estimation mainly comprised differentiating between an adult and a child especially in cases of defilement. Third molar eruption and tooth counting were among the routinely used methods by many of the health professionals in estimating age. Age estimation methods particularly third molar eruption were not uniform among the key informants. Generally, the methods used for age estimation in Uganda do not fully comply with International guidelines. Sub-study II showed that third molar eruption occurred earlier among females as compared to males. The overall mean age difference at the complete eruption stage between males and females ranged between 0.7-1.6 years. The earliest age observed clinically when the third molar is at complete eruption stage was at 14 years, while the latest age at this stage was 20 xviii years. Radio graphically, the earliest age at the complete eruption stage was first observed at 13 years and by 18 years close to 50% had the third molar at complete eruption, while by age 20 all the teeth were at full eruption stage. Generally, there was no significant differences (P>0.05) in mean age at the complete eruption stages using the clinical and radiographic methods except for teeth 38 & 48 among the females (P<0.05). The mean differences ranged between 0.1-0.7 years. The overweight category was significantly associated with age of third molar eruption; β = −0.95 (95% CI: −1.79, −0.11, P =0.026). The overweight participants had their third molar erupt about 10 months earlier than their normal-weight counterparts. There was no significant association between the socioeconomic status and age of eruption of the third molar. Sub-study III showed that third molar crown completion/ root initiation at stages D (Demirjian) and Ri (Moorrees) was observed at 12.6 and 13.5 years for females and males respectively. While apex closure at stages H (Demirjian) and Ac (Moorrees) was observed at 19.8 and 20.1 years for females and males respectively. Females developed root stages earlier compared to males and the mean age differences ranged between 0.9 to 1.4 years. There were statistically significant differences in Demirjian root stages E, F and G and MFH/Haavikko stages Ri, R1/4 and R1/2 between the sexes (P < 0.05). The probability of identifying an individual as being equal or older than 12, 14, 16 and 18 years using the Demirjian, Solari, Havikko, and Moorrees root development stages was quite high ranging between 80-100%. The study established that Demirjian and Moorrees root stages should be considered as good tests for discriminating for ages 16 and 18 and thus useful for forensic purposes in the Ugandan population. Conclusions: The findings of the sub-studies showed that that the current age estimation practice in the country has challenges and therefore may not be optimal for practice. Hence, a review of the current guidelines should be undertaken with the aim of adopting more credible and robust methods. Further-more these findings showed that third molar eruption is not a reliable method for age estimation in this population. The findings provide a platform for scientifically generated standards for age estimates for third molar development specific to the Ugandan adolescents and young adult population for forensic use. Keywords: Third Molar, Third Molar Eruption, Third Molar Development