Single-tooth-based dental age estimation in children: a modified Demirjian and Nolla approach using first permanent...

The aim of this study is to evaluate the relationship between the chronological age and developmental stages of permanent first molars in Turkish children under 12 years of age using panoramic radiographs and to compare the accuracy and consistency of the Demirjian and Nolla methods.

Panoramic radiographs of 1174 children (609 females, 51.9%; 565 males, 48.1%) aged between 5.0 and 12 years were retrospectively analysed from the archives of Istanbul Kent University, Faculty of Dentistry. Permanent first molars were evaluated using modified Demirjian (A-H) and Nolla (0-10) developmental staging approaches. Data were analysed using the Kolmogorov-Smirnov, Shapiro-Wilk, Wilcoxon tests, and Intraclass Correlation Coefficients (ICC).

The mean chronological age was 8.67 ± 2.04 years. Dental age estimated by the Demirjian method was significantly lower than chronological age (p < 0.05), with a mean difference of 1.91 ± 1.08 years for tooth 16 and 1.80 ± 1.15 years for tooth 36. The Nolla method also underestimated chronological age, but by a smaller difference (0.73 ± 1.10 years; p < 0.05). Both methods showed high consistency ICC values (Demirjian: 0.918-0.933; Nolla: 0.924-0.934). The direction of the sex difference depended on the conversion applied: girls appeared slightly more advanced by the Demirjian estimate, whereas boys did by the Nolla estimate, rather than reflecting a single consistent biological pattern.

Both methods demonstrated strong correlations between dental and chronological ages. However, whilst the Demirjian method tended to underestimate age, the Nolla method provided estimates closer to chronological age. Therefore, the Nolla method appears to be more suitable for dental age estimation in Turkish children.