Before we get into the nitty-gritty of how this works, it might be helpful to touch on some relevant dentistry basics for those of us without a DMD. It turns out our teeth are actually capable of regenerating a small amount of dentine -- the super-hard tissue that makes up most of your tooth -- after they get damaged or start to decay, but not enough to properly protect themselves against further damage. This is why dentists drill down into an ailing tooth, past freshly formed dentine, to fill a cavity with cement. It's a reliable treatment, but it's super-uncomfortable. Not to mention, aging fillings often need to be replaced, and can leave you prone to infection, facing down a dreaded root canal.