| dc.description.abstract | Aim: Tooth staging techniques are subjective and prone to bias. The aims of this thesis were to assess intra-observer reliability of permanent tooth staging techniques (Nolla, Moorrees et al. and Demirjian et al.) and explore crown-root ratios as an alternate method. Methodology: The reliability sample was archived cross-sectional panoramic radiographs of 200 children (100 males, 100 females) aged 6-15. Seven permanent teeth on the left side were scored twice using Nolla, Moorrees, and Demirjian methods. Weighted Kappa and percentage agreement were calculated. The sample for crown-root ratio was panoramic radiographs of a 100 male and 100 female subjects aged 16-25. Mean crown-root ratios (crown height/root length) for each tooth type (left side) were calculated using ImageJ. Student t-test was used to compare between tooth type and sexes. Moorrees root fractions derived from mean root lengths were defined in terms of crown-root ratios. A separate sample of 62 radiographs of individuals (aged 9-24) with developing roots were assessed comparing Moorrees’ staging and crown-root ratio. Accuracy was defined as percentage of teeth with crown root ratio within defined limits. Result: Results showed excellent reliability with Kappa values of 0.918, 0.922 and 0.938 for Demirjian (N=2682), Nolla (N=2698) and Moorrees (N=2674) respectively. Results for mean crown root ratios from 3019 teeth by tooth type ranged from 0.49-0.68 with third molars having highest ratios. The ratio for some tooth types differed significantly (P<0.01) between sexes. The accuracy of using crown-root ratio over root fractions showed an increasing accuracy with root stage, however, the sample included few early or mid-root fractions. Conclusion: These findings showed that reliability of permanent teeth using Demirjian scoring is marginally more reliable than Nolla or Moorrees. Crown-root ratio has potential as a less subjective approach to assess root growth stages than root fractions in dental age estimation. | en_US |
