Molecular Mechanisms Regulating Transition from Crown to Root Formation in the Development of Mouse Molars

Abstract

The tooth root is a foundation structure embedded in the alveolar bone of the jaws. Root formation starts after the completion of crown morphogenesis and proceeds slowly while coordinating the formation of the periodontal tissue that supports the tooth. Although several signaling pathways and transcription factors have been implicated in the regulation of molar crown development, relatively little is known about the regulatory mechanisms governing the transition from crown to root development. The formation of Hertwig's epithelial root sheath (HERS), consisting of 2 epithelial layers, is a key event in the initiation of root development. Recently, a new hypothesis about the mechanism of HERS formation was proposed based on the results of experiments using Fibroblast growth factor (Fgf) -10-deficient mice. In this review, we discuss this new hypothesis of HERS development and the signaling change for HERS formation during the transition process from crown to root development.