The London Atlas: developing an atlas of tooth development and testing its quality and performance measures

Abstract

Aim: To develop a comprehensive, validated, evidence based, practical, user-friendly atlas of dental age estimation and compare its performance with two widely used atlases. Methods: Based on the radiographic appearance of tooth development in 528 individuals aged 2-23 years and 176 neonates, the median stage of tooth development for each tooth in each age category/chronological year was used to construct diagrams representing ages between 28 weeks in-utero and 23 years were developed (The London Atlas) Accuracy was determined by ageing skeletal remains/radiographs of 1514 individuals (aged 32 weeks in-utero to 23 years) using The London Atlas (LA), the Schour and Massler (SM) and Ubelaker (Ub) atlases. Estimated age was compared to real age. Bias, absolute mean difference and proportion of individuals correctly assigned by age were calculated. Intra-observer variation (Kappa) was measured by re-assessment of 130 radiographs. To test the application of The London Atlas, a questionnaire was used to validate its use. Ninety 3rd year dental students were divided randomly into three subgroups, and blinded from the researcher. Each group used one of the 3 atlases to estimate the radiographic age of 6 individuals and complete a questionnaire focussed on the design, clarity, simplicity and self-explanation of the three atlases. Results: Excellent reproducibility was observed for all three atlases (Kappa: LA 0.879, SM 0.838 and Ub 0.857). LA showed no bias (P=0.720) and correctly estimated 53% of cases. SM and Ub showed significant bias by consistently underestimating age (P=0.026 and P=0.002) with 35% and 36% correctly estimated for SM and Ub respectively. The mean absolute difference for LA (0.72 years) was smaller than SM (1.15 years) and Ub (1.17 years). LA was preferred over the other two atlases in all quality measures tested (clarity, design, simplicity and self-explanation). Conclusion: The London Atlas represents a substantial improvement on existing atlases facilitating accurate age estimation from developing teeth. Development of interactive online and mobile app versions is complete.