Because it wasn't necessary. First off, as others have noted, teeth are not bone. They are similar to bone, but they are not the same. See Sunil Kumar Gopal's answer for a full description of teeth. Mostly though, it's just not needed. read more
Wolverine got his bones fused with adamantium, and teeth are not made of bones. (Image from WebMD). The bone part of Wolverine's jaw, I would expect, would also have been coated with adamantium. read more