Spatiotemporal interplay between epithelial and mesenchymal cells drives human dentinogenesis.

Tooth dentin, secreted by odontoblasts, constitutes most of the tooth structure and provides support and sensory function. However, dentin defects are common and irreparable once they exceed a critical threshold. Human dentin develops from dental papilla (DP) cells under the guidance of the dental epithelium (DE). Here, we present a human tooth development atlas from initiation to erupted stage using single-cell RNA sequencing and spatial transcriptomics, focusing on epithelial-mesenchymal interactions. This atlas reveals that DE orchestrates DP differentiation in a WNT-NOTCH sequential activation model and identifies the key signaling molecules. DLX6-AS1(+) DP cells respond to dental epithelial signals and can be isolated from adult dental pulp stem cells (DPSCs). Notably, DLX6-AS1(+) DPSCs successfully generate tubular dentin in an in vivo disease model of dentin defects. This research provides valuable information on human tooth development and establishes a basis for repairing regenerative dental tissue.