RESEARCH ARTICLE Topical Application of Lithium Chloride on the Pulp Induces Dentin Regeneration

We herein describe a novel procedure for dentin regeneration that mimics the biological pro-cesses of tooth development in nature. The canonical Wnt signaling pathway is an impor-tant regulator of the Dentin sialophosphoprotein (Dspp) expression. Our approach mimics the biological processes underlying tooth development in nature and focuses on the activa-tion of canonical Wnt signaling to trigger the natural process of dentinogenesis. The coronal portion of the dentin and the underlying pulp was removed from the first molars. We applied lithium chloride (LiCl), an activator of canonical Wnt signaling, on the amputated pulp sur-face to achieve transdifferentiation toward odontoblasts from the surrounding pulpal cells. MicroCT and microscopic analyses demonstrated that the topical application of LiCl in-duced dentin repair, including the formation of a complete dentin bridge. LiCl-induced dentin is a tubular dentin in which the pulp cells are not embedded within the matrix, as in primary dentin. In contrast, a dentin bridge was not induced in the control group treated with pulp capping with material carriers alone, although osteodentin without tubular formation was in-duced at a comparatively deeper position from the pulp exposure site. We also evaluate