In a breakthrough that could change the history of dentistry, Japanese scientists led by Dr. Katsu Takahashi have begun human clinical trials for a drug capable of naturally regenerating teeth.The drug blocks the USAG-1 protein, which reactivates a biological mechanism that could allow the development of a “third set of teeth.” After successful results in mice, ferrets, and dogs, it is now being tested in children with congenital absence of permanent teeth.