Research groups around the world are working to find ways to implant or grow real biological teeth in a human jaw.

Discover what exponential growth is, learn how it differs from other growth types, and explore real-life examples like compounding interest and population growth.

Editor’s note: This spray is now back in stock in both sizes, so we’ve updated the links below accordingly. I have been a terrible sleeper ever since I had kids. My 8-year-old asked me if I stay awake ...