Meeting Abstract
Reptiles with continuous tooth replacement, or polyphyodonty, replace their teeth in predictable, well-timed waves in alternating tooth positions around the mouth. This process is thought to occur irrespective of tooth wear or breakage. However, premature extraction of functional teeth in alligators stimulates dental epithelial cell proliferation, potentially leading to faster tooth replacement. Therefore, without a long-term study, it is unknown if these early changes in cell proliferation lead to more rapid tooth replacement or if timing is in fact intrinsically controlled. Furthermore, it is unknown if this proliferation is unique to crocodilians or is characteristic of all reptiles. In this study, we aimed to determine if tooth extraction affects tooth replacement timing long-term in juvenile green iguanas. We analysed an historical collection of x-rays collected for up to 7 months after functional tooth extraction. We also performed new extraction experiments for molecular characterization of dental tissues. Results show that premature tooth extraction has no effect on tooth replacement timing, and teeth are replaced on average every 20 weeks at each position. Cell proliferation is not detected until 12 weeks after extraction in the successional lamina, matching the expected development time of a tooth in iguanas. The differences observed in molecular activity in the successional lamina between alligators and iguanas could be due to the morphology of the dental lamina and maintenance of potential stem cells, tooth attachment type, or feeding ecology. Ongoing longitudinal studies in the alligator and leopard gecko will further elucidate the mechanisms of continuous tooth replacement in polyphyodont reptiles.
