The accuracy and precision of the third mandibular molar as an indicator of chronological age.

The study was designed to investigate the accuracy and precision of the development of the third mandibular molar, determined on panoramic x-rays, as an indicator of chronological age- a method which is used in Sweden to estimate chronological age in certain young foreign individuals with uncertain birth records. Accuracy test: The mean difference between the estimated and true chronological age was determined in a sample of 372 14.5-24.5-year-old subjects. The data were arranged in subgroups according to sex and age. The accuracy test showed a systematic underestimation of age, increasing with age in both sexes. The 95 per cent confidence interval of the difference between estimated and true chronological age was large, about +/- 4.5 years in girls and +/- 2.8 years in boys. The association between dental age and chronological age, expressed in correlation coefficients, was poor. Precision test: The intra-examiner error was low but the 95 per cent confidence interval of the difference was large, +/- 0.8 years. The dental development of the third mandibular molar should not be used for estimation of chronological age in individual subjects, due to its very low accuracy.