Meeting Abstract
30.6 Jan. 5 Building divergent dentitions by regulation of tooth addition SMITH, Moya M; KCL Dental Institute Guy’s and St Thomas’ Hospitals moya.smith@kcl.ac.uk
The dentition in each clade of gnathostomes is unique and shows great diversity in patterns for tooth addition and replacement, each adapted to a specific feeding niche. The formation of a sub-epithelial dental lamina promotes regulated tooth development with distinctive replacement patterns. The evolution of such a structure, judged essential to produce patterned teeth at the margins of the jaws, may have occurred independently in more than one gnathostome group and is not as classically thought, a conserved and plesiomorphic character of jawed vertebrates. This character �teeth produced from a dental lamina� occurs more than once on a gnathostome phylogeny suggesting non-homologous developmental mechanisms. This may imply that the gene network necessary to regulate tooth patterning in mammals, assumed to be dependent on the dental lamina, could have evolved more that once. Teeth are capable of renewal in a specific spatial temporal pattern, reflected by an initial differential spatial temporal gene expression pattern. However, this pattern may also vary between dentate bones in the one dentition in bony fish, and tooth shape may also vary between upper and lower jaws in chondrichthyans. A universal developmental model has been suggested where all toothed fields start from a pioneer tooth on each bone or jaw, which autonomously regulates the pattern of tooth addition in the row and then subsequently for all successive replacement teeth in each family. Data on the development of tooth sites for succession of teeth either, without or from, a dental lamina in non-model animals from osteichthyans as well as chondrichthyans will be discussed. This may involve a mechanism for retaining a localised progenitor cell population for continuous tooth renewal deep to the oral surface and is considered essential to regulate tooth addition to each specific pattern.
