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 (FT) extraction, including proliferation and β-Catenin expression, for up to 12 weeks. We then compared these results to a newly analyzed historical dataset of X-rays collected up to 7 months after FT damage and extraction in the green iguana. Results show that proliferation in the dental and successional lamina (SL) does not change after extraction of the FT, and proliferation occurs in the SL only when a tooth differentiates. Damage to an FT 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 FT. These results suggest that traumatic FT loss affects the timing of the replacement cycle at that one position, which may have implications for tooth replacement patterning around the entire mouth.

中文翻译：

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过早拔牙和损伤对绿鬣蜥更换时间的影响

具有连续牙齿更换（或称多齿牙）的爬行动物会以可预测的、适时的波浪方式在口腔周围交替牙齿位置来更换牙齿。人们认为这个过程的发生与牙齿磨损或破损无关。在这项研究中，我们的目的是确定牙齿损伤和过早拔牙是否会长期影响幼年绿鬣蜥（鬣蜥）的牙齿更换时间。首先，我们使用 BrdU 脉冲追踪分析对正常牙齿发育进行组织学检查，以检测替换牙齿和牙组织中的标记保留细胞。接下来，我们进行了长达 12 周的拔牙实验，以表征功能性牙齿 (FT) 拔除后的牙组织，包括增殖和 β-连环蛋白表达。然后，我们将这些结果与新分析的绿鬣蜥 FT 损伤和提取后 7 个月内收集的 X 射线历史数据集进行比较。结果表明，拔除 FT 后，牙齿和继承椎板 (SL) 中的增殖不会发生变化，并且仅当牙齿分化时，SL 中才会发生增殖。FT 牙冠的损坏不会影响牙齿更换周期的时间，但是，完全拔牙可以消除 FT 吸收的需要，从而将更换周期提前 4 周。这些结果表明，创伤性 FT 损失会影响该位置的更换周期的时间，这可能对整个口腔周围的牙齿更换模式产生影响。