牙齿发育受到上皮－间充质相互反应的高度调控，多种因子及其介导的信号通路参与其中相互协调。近年的研究发现上皮组织中的Wnt/β-catenin信号通路在牙齿发育中发挥重要作用，而在间充质细胞和组织中持续激活β-catenin对牙齿发育的影响尚无系统研究。前期实验中，我们以I型胶原为启动子，使用Cre/LoxP Tamoxifen系统敲除β-catenin的第三外显子，导致β-catenin降解受阻得以持续激活，发现小鼠磨牙牙根变短，萌出延迟，切牙长度变短，成牙本质细胞终末发育障碍。本项目将在前期实验的基础上，采用不同时相点注射Tamoxinfe，准确系统观察在间充质细胞中持续激活β-catenin对牙齿发育的影响及其具体下游信号通路，同时初步探讨间充质细胞中持续激活β-catenin致牙齿萌出延迟的机制。本研究将丰富牙齿发育调控的理论基础，并为牙再生和寻找牙齿发育异常的治疗措施提供线索。

Tooth development is a complex biological process, which depends on epithelial-mesenchymal interactions and the mutual regulation of multiple factors. The previous studies have shown that Wnt/β-catenin pathway in epithelial tissue plays very important roles during tooth development. However, the effects of constitutive activation of β-catenin in mesenchyme on tooth development is still unkown. Using ColⅠpromoter and Cre/LoxP tamoxifen system, we constitutively activated β-catenin in mesenchymal cells, which caused the root of molars and the length of incisors shortened, tooth eruption delayed and terminal differentiation of odontoblasts impaired. Based on these findings, using conditional knockout and transgenic mice, we further focus on the effects of constitutive activation of β-catenin in mesenchymal cells and odontoblasts on tooth development and its downstream signaling pathway. Our results will be helpful for clarifying the effects of Wnt/β-catenin pathway on tooth development and mechanism of delayed tooth eruption, broadening our understanding and developing new treatment strategies for tooth regeneration and abnormalities of tooth development.