Trin....I wouldnt worry to much about addiction in the short term because people who are in real pain have a much lower likelihood of becoming addicted to them. As you know I have been on long term medications for years and I am not addicted. If I had to stop tomorrow I could do it but I would be in pain. The worst thing that might happen is some tummy distress for a day or two.
I would also hope they are giving him pain medications meant for acute pain and not chronic pain. Nothing chaps me off more than to hear that doctors are giving long term pain medications for a short term problem.
On to other things...I am very glad to hear that his mouth is going to be okay. Hugs to all.