PROJECT SUMMARY Genetic diseases such as tooth agenesis, dentinogenesis imperfecta, infectious diseases such as caries or fractures represent common public health problems that affect up to 30-40% of the population worldwide and impose significant burdens on patients (Centers for Diseases Control and Prevention, 2019). The estimated direct costs of dental diseases amounted to $356.80 billion, totaling worldwide costs due to dental diseases of $544.41 billion in 2015. Given the unabated rise of dental diseases prevalence in the general population, it can only be expected that the number and cost will intensify in the future. As tooth regeneration remains elusive, restoring function and esthetics is lengthy and expensive. Current efforts in the field of regenerative dentistry rely on the availability of methods that inject into tissues in vitro expanded heterogeneous multipotent stem cell populations or in vitro differentiated progeny of pluripotent cell lines. Due to insufficient characterization of the molecular signature of progenitor cell sources as to their capacity to generate functional differentiated cell progeny, these efforts lead to insufficient numbers of cells available for building new tissues. Thus, identifying the cellular and molecular identity of genes and pathways that reliably prompt cells to differentiate into one cell type and not another for instance would fulfil a major gap in our knowledge to reliably develop strategies for recreating these processes in stem cell therapies. The goal of this project is to identify the cellular and molecular identity of genes and pathways defining dental mesenchymal cell differentiation and fate early in tooth development and harness this information to develop potential therapeutics mainly for dentin regeneration.