Stem cells are found throughout the body, including the brain, heart, skin, and bones. Although scientists still haven’t pinpointed the exact role they play in maintaining, and possibly regenerating, our tissues and organs, one team recently switched on that healing process—by zapping dental stem cells with low-powered lasers. Reporting this week in the journal Science Translational Medicine, Harvard bioengineer Dave Mooney and his colleagues describe how laser light stimulated dental stem cells to produce dentin, the hard stuff underneath tooth enamel, in live rats and human in vitro cultures.