Estimating age and the likelihood of having attained 18 years of age using mandibular third molars.
OBJECTIVE
Age estimation methods using mandibular third molar (M3) root formation were tested. Diagnostic accuracy of M3 to predict age 18 was tested.


METHODS
Methods were tested on a target sample of 300 dental panoramic radiographs (age 11-25). Diagnostic accuracy was assessed on separate reference data (n = 1,663, age 9-25). Root stage was the diagnostic test predicting 18 years of age.


METHODS
Root stage of M3 was assessed and age estimated (n = 157) using published methods that use Demirjian or Moorrees root stages. The difference between dental and known ages was assessed. Diagnostic tests and likelihood ratios were calculated for reference data.


METHODS
Mean difference (bias), standard deviation and absolute mean difference between dental age and known ages. Likelihood ratio of age 18, given M3 root stage.


RESULTS
Only six of 37 methods estimated age with bias not significant to zero. Mean absolute difference between dental and known age for these methods ranged from 1.45 to 1.97 years. Standard deviation of bias for all methods was around 2 years and 95% confidence interval of estimated age is ± 4 years. The best methods using Demirjian and Moorrees stages are detailed. Likelihood ratio of being at least 18 if M3 was mature was 13.61. If M3 was 'A1/2' (apex half closed) or mature, on the balance of probabilities, estimated age was at least 18.


CONCLUSIONS
Most methods using M3 root formation estimate age with significant bias. If M3 is mature, age 18 is more than likely attained.
Senior Clinical Lecturer, Institute of Dentistry, Bart's and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK. h.m.liversidge@qmul.ac.uk
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Liversidge
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Marsden
D000293:Adolescent; D000328:Adult; D000366:Age Determination by Teeth / Q000379:methods*; D001459:Bangladesh; D015982:Bias; D044383:Black People / Q000706:statistics & numerical data; D002648:Child; D016001:Confidence Intervals; D005006:Ethnicity / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D016013:Likelihood Functions; D008131:London; D008297:Male; D008334:Mandible / Q000000981:diagnostic imaging; D008964:Molar, Third / Q000000981:diagnostic imaging / Q000502:physiology*; D009805:Odontogenesis / Q000502:physiology*; D011237:Predictive Value of Tests; D011336:Probability; D011862:Radiography, Panoramic; D012680:Sensitivity and Specificity; D013019:South Africa; D019227:Tooth Apex / Q000000981:diagnostic imaging / Q000502:physiology; D014092:Tooth Root / Q000000981:diagnostic imaging / Q000502:physiology*; D044465:White People / Q000706:statistics & numerical data; D055815:Young Adult