Try laying him on his back rubbing his belly. Then rub his face.
I gently grab the upper and lower jaw with different hands.
Then see if you can reach in. Try to sweet talk him...relax him first. Hopefully he will be putty in your hands.
Bella got a piece of bully stick stuck in the back of her teeth. she just kept chewing and chewing like she had gum. it was pretty funny.
she doesnt care though...i just reached in and pulled it out.
I think she knew what was happening.
Good luck