lthough secular changes in human growth are frequently reported in the literature, a secular trend in dental maturation has not been consistently shown to date. Objectives: In this study, we compare root formation in a modern sample of living Portuguese children (n = 521), between 6 and 18 years of age, with that of a similar sample of known sex and age Portuguese child skeletons (n = 114), who lived half a century earlier, to assess secular change in dental maturation. Methods: The roots of seven developing permanent mandibular teeth were assessed for their maturation in both samples. The median age-of-attainment of root stages was calculated using logistic regression and compared between the samples. The potential influence of mortality bias in root development of the skeletal sample was tested. Results: No mortality bias effect was detected. We find that the dentition of modern Portuguese boys and girls mature on average 1.22 years and 1.47 years earlier, respectively, compared to their counterparts born one half a century before. Our results also suggest that an earlier timing of attainment of root formation maturational stages was not accompanied by a change in the overall duration of root formation. Conclusions: We demonstrate a clear and consistent acceleration in dental root maturation due to secular changes and show that the plasticity in dental development in response to environmental factors is greater than previously thought.