I second what paul and David have said. I know you have seen ENTs - so in this case with them all saying you do not have cancer, what you need to do is be diligent. No one can diagnose cancer if it is not yet present. If you have a specific area of concern, then they can biopsy it, but usually they have to be able to see it or at the very least FEEL it - as in a lump, or lesion, or even have a reactive node. So ideally you go for regular dental check ups with a dentist, keep a close eye on your mouth so you know what is normal, and finally see an ENT - someone who knows Oral cancer - regularly. Maybe every three to 6 months? Or if anything in your mouth changes. best of luck.