Beta-catenin is required in odontoblasts for tooth root formation, according to a new study in the Journal of Dental Research (January 23, 2012).
While the molecular and cellular mechanisms of early tooth development and crown morphogenesis have been extensively studied, little is known about the molecular mechanisms controlling tooth root formation, noted the study authors, from the Chonbuk National University School of Dentistry.
Beta-catenin is strongly expressed in odontoblasts, they noted, and tissue-specific inactivation of beta-catenin in developing odontoblasts produces molars lacking roots and aberrantly thin incisors, the study found.
At the beginning of root formation in the mutant molars, the cervical loop epithelium extended apically to form Hertwig's epithelial root sheath (HERS), but root odontoblast differentiation was disrupted and followed by the loss of a subset of HERS inner layer cells. However, the outer layer of HERS extended without the root, and the mutant molars finally erupted. The periodontal tissues invaded extensively into the dental pulp.
These results indicate that there is a cell-autonomous requirement for Wnt/beta-catenin signaling in the dental mesenchyme for root formation, the researchers concluded.
