The knowledge of dental morphometry, especially of its radicular portion, is of great importance for certain dental specialties, such as, endodonty. Regarding the permanent lower anterior teeth we know that its morphology and root length, are variable. The aim of this study was to analyze the average length of the dental roots of permanent lower anterior teeth in Brazilian individuals. The average root length obtained in this study for the lower central incisors was 13.07 mm; to lower canines the value found was 15.81 mm; the average value for the radicular portion of lower lateral incisors was 13.08 mm. We conclude that the mean value for the length of the radicular portion of permanent lower central incisors is similar to that found for permanent lower lateral incisors, because they have similar anatomical features. Among the lower incisors and lower canines the discrepancy is greater because the lower canines are bulkier. Furthermore, we could conclude that the values obtained in our study may be used as a parameter to characterize the average length of the dental roots of permanent lower anterior teeth in Brazilian individuals.