Comparison between Nolla and Demirjian dental age assessment methods: a Systematic Review

Background: Estimation of age has great importance in clinical practice, not only in orthodontics, being commonly used forensic medicine, radiology and paediatrics. For this reason, the Nolla and Demirjian methods have been developed. Several studies have been performed to determine the chronological age analysing the dental mineralization stage, however, it is not a straightforward analysis. The aim of our study is to estimate the observed differences between Chronological age (CA) and Dental age (DA) when the two assessment methods have been used. Materials and Methods: A systematic search of literature for papers utilizing the Nolla and Demirjian datasets for age estimation was performed. All language articles from PubMed, Lilacs and Scopus databases were electronically searched for terms ‘Nolla’, ‘Demirjian’ and ‘Dental age’ published till October 2016. Results: A total of 2,268 studies were identified from which 64 studies were included for qualitative analysis and 42 studies observed the eligibility criteria for quantitative assessment. When synthesizing the estimation results from different population groups, on average, the Demirjian dataset overestimated the age of females by 0.65 years (0.10 years to 2.82 years) and males by 0.60 years (0.23 years to 3.04 years). Conclusions: The Demirjian method tends to overestimate age by more than six months, whereas the Nolla method tends to underestimate it. These methods should be used only with considerable caution, when applied to subjects of any global population.