My TB didn’t try to bite me, but put everything in his mouth, and shut his jaw. Loved to nuzzle cat fur, but then tried picking said cat up in his jaw. Ouch, did the same with a horse friendly dog.
Because I knew he was a doofus, and had not intention of biting, like a poster above, I learned how to rub his gums, above his teeth. He loved that.
In his later years X-rays showed rotted teeth that had stayed in his mouth via deterioration.
So he had tooth problems for a long while. He also would grind his teeth on one side if you made too much contact thru the reins (when collecting).
None of this was accompanied by ear pining or snark faces. Does your horse pin his ears and switch his tail when attempting to bite?