The average adult human body contains 206 bones—the hardened mixtures of calcium, minerals, and collagen that provide the biological scaffolding that walks us through our day. While we may not think of them much, bones are incredibly resilient. But if they do break, they have this nifty trick of regrowing themselves.

Teeth, however, are not bones. Although they’re made of some of the same stuff and are the hardest material in the human body (thanks to its protective layer of enamel), they lack the crucial ability to heal and regrow themselves. But that may not always be the case. Japanese researchers are moving forward with an experimental drug that promises to regrow human teeth. Human trials began in September 2024.