Ror2-mediated non-conanical Wnt signaling in the dental mesenchyme plays a crucial role in mouse molar root development

The mammalian tooth root development begins after the completion of crown formation and is regulated through epithelial-mesenchymal interactions. Canonical Wnt/β-catenin signaling plays important role in tooth root formation. Wnt5a ligand, one component of the non-canonical Wnt signaling pathway, is associated with tooth development. However, its function during root formation is still unknown. The aim of this project is to investigate if mesenchyme- and epithelium-derived non-canonical Wnt signaling regulates tooth root development. Epithelial-specific deletion of Ror2 at E14.5 has no effects on root formation. Mesenchymal- and epithelial-specific loss-of-function of Ror2 in the apical region at PN3.5 caused a mild phenotype with a little shorter root. However, loss of Ror2 in dental mesenchyme resulted in a much shorter root with decreased odontoblast differentiation at PN21.5. These data indicate that loss of Ror2 in dental mesenchyme inhibits postnatal root development.