Although the third molar is the tooth with the greatest anatomical and developmental variability, some authors consider it important to estimate whether a subject is of legal age or not. The Demirjian?s technique is the most widely used tool to estimate dental age and was therefore used in our study to assess possible correlation between the age of majority and the maturational degree of the lower third molars, evaluated through radiographic images. This observational transversal study was conducted on 180 panoramic radiographs from consecutive patients. The degree of maturation of the lower third molar was independently classified by two observers, according to the Demirjian´s maturational stage method. A total of 180 patients ? 65 men (36.12%) and 115 women (63.88%) ? were included (mean age 21.6 years; standard deviation 5.2). The age range of our subjects corresponded to maturational stages D to H in the Demirjian?s classification. A logistic regression analysis showed that subjects classified into the highest maturational stage H had a significantly higher probability of being considered of legal age by both observers, as compared with subjects in the lowest stage D. Inter-observer agreement was very high. Gender predictive capacity was not observed. Our results showed that subjects with the lower third molars in the highest maturational stage could be estimated to be older than 18 years and therefore considered of legal age, a finding also reported by other authorsThe Demirjian´s tooth maturational stage method, applied to the lower third molars, can be reliably used to estimate whether an individual is of legal age (18 years or older). High concordance between different observers using this method can be expected.