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. In this study, we aimed to determine if damage to teeth and premature tooth extraction affects tooth replacement timing long-term in juvenile green iguanas (Iguana iguana). First, we examined normal tooth development histologically using a BrdU pulse-chase analysis to detect label retaining cells in replacement teeth and dental tissues. Next, we performed tooth extraction experiments for characterization of dental tissues after functional tooth extraction, including proliferation and ß-Catenin expression, for up to 12 weeks. We then compared these results to a newly analysed historical dataset of X-rays collected up to seven months after functional tooth damage and extraction in the green iguana. Results show that proliferation in the dental and successional laminae does not change after extraction of the functional tooth, and proliferation occurs in the successional lamina only when a tooth differentiates. Damage to a functional tooth crown does not affect the timing of the tooth replacement cycle, however, complete extraction shifts the replacement cycle ahead by 4 weeks by removing the need for resorption of the functional tooth. These results suggest that traumatic functional tooth loss affects the timing of the replacement cycle at that one position, which may have implications for tooth replacement patterning around the entire mouth.