Tooth number abnormality is one of the most common dental developmental diseases, which includes both tooth agenesis and supernumerary teeth. Tooth development is regulated by numerous developmental signals, such as the well-known Wnt, BMP, FGF, Shh and Eda pathways, which mediate the ongoing complex interactions between epithelium and mesenchyme. Abnormal expression of these crutial signalling during this process may eventually lead to the development of anomalies in tooth number; however, the underlying mechanisms remain elusive. In this review, we summarized the major process of tooth development, the latest progress of mechanism studies and newly reported clinical investigations of tooth number abnormality. In addition, potential treatment approaches for tooth number abnormality based on developmental biology are also discussed. This review not only provides a reference for the diagnosis and treatment of tooth number abnormality in clinical practice but also facilitates the translation of basic research to the clinical application.

牙数异常是最常见的牙齿发育疾病之一，包括牙发育不全和多生牙。牙齿发育受许多发育信号的调节，例如众所周知的 Wnt、BMP、FGF、Shh 和 Eda 通路，它们介导上皮和间充质之间正在进行的复杂相互作用。在此过程中这些关键信号的异常表达可能最终导致牙齿数量异常的发展；然而，潜在的机制仍然难以捉摸。本文综述了牙齿发育的主要过程、机制研究的最新进展和最新报道的牙齿数量异常的临床研究。此外，还讨论了基于发育生物学的牙数异常的潜在治疗方法。