If you risk it make sure you check in early as your airline may insist on a return ticket out of the kindom or a ticket back to Country of origin from another country with a onward ticket from Thailand or cross land borders into the surounding countries as on the news at the moment the hot topic seems to be overstaying foreigners
if you register at the university hospital its where I got mine done as it was a complex extraction as they had to cut them out not a straight forward extraction so could have been cheaper at a normal dentist
I had two wisdom teeth removed in the Bangkok hospital as the dentist couldnt do it as it was a operation to get them out I think it was about 10,000 baht with the medication which compared to the Uk dentist its cheap