The coroner says that the tooth of the bull shark that killed the girl was left in her body because the shark was young, and its jaw was still developing. But sharks of all breeds loose teeth on an almost daily basis, regardless of their maturity.
When the Ocean institute man reveals to Game Warden that it's a bull shark, the paperwork reflects a great white.
In one of the underwater shots (before the sheriff is killed) shows a shark with a lunate tail, which in only found in the great white and mako sharks.
I'm also pretty sure the main artwork for the movie depicts a great white rather than a bull shark (they have a blunt snout)