Evaluating the Nolla Method for Dental Age Estimation in Children from Northwestern Romania.

Abstract

Background/objectives: Dental age estimation plays a critical role in pediatric dentistry, orthodontics, and forensic medicine. The Nolla method, widely applied globally, has shown variable accuracy across different populations. This study aimed to evaluate the applicability and accuracy of the Nolla method in estimating the dental age of Romanian children and to identify potential discrepancies between dental and chronological ages.

Methods: A retrospective analysis was conducted on 860 panoramic radiographs from pediatric patients aged 3-15.9 years in Oradea, Romania. The Nolla method was applied to estimate dental age, and the results were compared with chronological age. Statistical analyses, including Wilcoxon signed-rank and Mann-Whitney U tests, were performed to evaluate the accuracy and consistency of the Nolla method.

Results: The study analyzed 860 panoramic radiographs (356 boys and 504 girls). The average chronological age was 9.95 ± 2.48 years, while the average dental age, as estimated using the Nolla method, was 8.43 ± 2.13 years. Dental age was consistently lower than chronological age, with a median difference of 1.5 years (IQR: 0.9-2.2 years). Among the 13 age groups, the highest representation was found in the 8-8.9-year (14.7%) and 9-9.9-year (13.3%) groups. Gender differences were statistically significant (p < 0.001); girls demonstrated a larger median discrepancy of 1.7 years (IQR: 1.1-2.3 years) compared to boys at 1.15 years (IQR: 0.6-1.8 years). Notably, discrepancies increased with age, peaking at 2.6 years in the 14-14.9-year group (4.7% of the sample). The youngest group (3-3.9 years) showed the smallest difference of 0.3 years. Significant differences between chronological and dental ages were observed in 87.5% of the sample.

Conclusions: The Nolla method consistently underestimated dental age in Romanian children, with greater discrepancies in older age groups and among girls. These findings highlight the need for the population-specific calibration of the method to improve its accuracy in both clinical and forensic contexts.