The human dentition shows the general characteristics of a complex adaptive system. Interactions at a molecular level of genetic, epigenetic and environmental factors lead to the emergence of tooth germs. Subsequently differentiated specialised cells control mineralisation and then mature teeth emerge, showing marked variation. The mature dentition provides a record of developmental influences from its initiation at 6 weeks in utero to its completion at 20 years of age. It is, therefore, a valuable paradigm of general development.The substantial collection of skeletal material of 200-400 AD Romano-Britons from Poundbury, Dorset, has been extensively studied, providing much evidence concerning lifestyle and medical conditions. In this study, we investigate further findings concerning dental development. The aims are to compare the findings with those for Modern Britons and to identify the effects of major factors known to affect the Romano-Britons in order to consider the possible synergism of these effects. The findings were that the patterning of the dentition, its sexual dimorphism and the types of developmental defects were similar to modern Britons. However, the RomanoBritons had more anomalies, generally smaller tooth crowns and roots, and more severe enamel defects. Thus, the Romano-Britons' dentition showed evidence of insults occurring at all stages of tooth development. These effects, occurring over a long period of time and affecting tissues with different genetic backgrounds, probably arise from ongoing major environmental insults known to be present in Poundbury. These insults have been identified as excess lead ingestion, poor nutrition and recurrent infections. We propose that these factors, acting synergistically, constituted marked environmental stress affecting development.

No abstract

Dental development is a complex adaptive system influenced by genetic-epigenetic-environmental factors. The mature dentition is a paradigm for general development and is an accessible, permanent record of interactions affecting development from 6 weeks in-utero to 20 years of age. Published research on the dentition of a large group of Romano-Britons has indicated that three major environmental insults acting throughout the developmental period are associated with high frequencies of dental variations. Based on those studies and the literature, the aetiological network incorporates the effects of excessive lead ingestion, poor nutrition and infections on the endocrine and immune systems, epigenome and gene expression. The environmental insults act independently and synergistically on both the endocrine and immune systems, which in turn have reciprocal interactions with each other, as well as on the epigenome. Thus, a complex subnetwork influences the epigenome and modifies one or more of three mechanisms by which it controls gene expression, that is, DNA methylation, post-translational histone modification and microRNA expression. The environmental-epigeneticgenetic interactions behave as a complex adaptive system that can be illustrated in a network diagram. The epigenetic modifications can have long-term health effects in the individual and some may also be heritable.