The Morphogenesis, Pathogenesis, and Molecular Regulation of Human Tooth Development-A Histological Review.

Odontogenesis, the development of teeth, is a complex, multistage process that unfolds from early embryogenesis through tooth eruption and maturation. It serves as a classical model of organogenesis due to the intricate reciprocal interactions between cranial neural crest-derived mesenchyme and oral epithelium. This narrative review synthesizes current scientific knowledge on human tooth development, tracing the journey from the embryological origins in the first branchial arch to the formation of a fully functional tooth and its supporting structures. Key morphogenetic stages-bud, cap, bell, apposition, and root formation-are described in detail, highlighting the cellular events and histological features characterizing each stage. We discuss the molecular and cellular regulatory networks that orchestrate odontogenesis, including the conserved signaling pathways (Wnt, BMP, FGF, SHH, EDA) and transcription factors (e.g., PAX9, MSX1/2, PITX2) that drive tissue patterning and cell differentiation. The coordinated development of supporting periodontal tissues (cementum, periodontal ligament, alveolar bone, gingiva) is also examined as an integral part of tooth organogenesis. Finally, developmental anomalies (such as variations in tooth number, size, and form) and the fate of residual embryonic epithelial cells are reviewed to underscore the clinical significance of developmental processes. Understanding the normal course of odontogenesis provides crucial insight into congenital dental disorders and lays a foundation for advances in regenerative dental medicine.