I had the same problem with Star and her teeth were really sharp. A trainer had me get a spray bottle of Gannicks Bitter Apple at the pet store. When she bit, we told her no and sprayed a little in her mouth. It does not harm the dog and it worked for us. Star is a hunting Airedale so her puppy biting had to be stopped before she got bigger.

BTW: Got her trained some now and she hunts birds like a Springer.