Evaluation of third molar eruption. Comparison of two stage classifications

A criterion in dental age diagnostics is assessment of the eruption stage of the third molars. As the reliability of an age diagnosis is crucially dependent on the stage classification used, the most suitable system should be implemented for age estimation purposes. The objective of the present study was to compare the reliability of two classifications for radiological assessment of third molar eruption described by Olze et al. (Int J Legal Med 2007, 121:445-448; Arch Kriminol 2012, 229:145-153). To that end 216 conventional orthopantomograms of German males and females in the age group between 15 and 25 years were evaluated by two observers (one dentist with 20 years professional experience and one dentist with 6 years professional experience). The weighted kappa coefficient was used to determine intraobserver and interobserver agreement, whilst the eta coefficient was determined as a measure of the correlation between age and eruption stage. Based on the synopsis of the calculated kappa and eta coefficients it was concluded that both stage classifications for determining the developmental status of third molar eruption under study can, in principle, be recommended for age estimation purposes as they both command similar high levels of precision and accuracy. Stage classification II appears particularly suitable for inexperienced examiners and for assessing X-ray images on which the gingiva is not clearly definable.