There is an ability called Strong Jaw that boosts the power of biting moves by 50%. This means the base power of the move, not your attack stat when you use a biting move.
The list of biting moves are:
Jaw Lock (Did not know this was a move)
This ability did not exist until X and Y, and prior to ORAS was the signature ability of Tyrantrum.
There is no item that boosts biting move power, but there are plenty of items that boost Physical attack, as all of the biting moves are physical. Life Orb, Choice Band, Muscle Band, etc.