02nd Apr 2019
Diverse tooth development staging techniques use a prediction of the mature tooth root length as a reference to classify the observed tooth development. Proportions of the predicted mature root length are used as tresholds between the root stages. Longitudinal data permit to collect information of a specific tooth position while in development and while mature. This information allows to establish the exact tooth development stage thresholds for the considered subjects and can be used to validate observers’ stage allocation performances.
Longitudinal tooth development data were extracted from 119 series of retrospectively collected digital dental panoramic radiographs. Each series included at least two radiographs from the same subject registered at different moments. The youngest radiograph contained mature and the older maturing second molars. All second molars were staged by six observers according to the technique of Köhler et al.. The ratio between the second molar root length measured in the last and each previously recorded radiograph was calculated for each subject. The calculated range of second molar root length ratios that confirmed correct Köhler staging were as follows: range=0.25 to <0.50, Stage 5; range=0.5 to <0.75, Stage 6; range=0.75 to <1, Stage 7; ratio=1 (i.e., no range), Stage 8-10. The registered Köhler stages and the calculated ratios were independently verified for each second molar position and for each of the six observers.
Verification of the calculated ratios and registered Köhler stages revealed that all observers generally classified the developing tooth in a more advanced stage than the correct stage, except for Stage 5.