Congratulations! There is no consensus when a routine scan should be done post treatment, other than for any suspicions. In fact, the NCCN guidelines for the post treatment scan is recommended 3-6 months, but only for certain H&N cancers, like oropharyngeal, a few others, but only for T3 and T4 disease, and not others. This is just a guideline, and my experience at several hospitals was a scan at 3 months post treatment, and a scan every 6 months thereafter, but I never made it to that point before I had a recurrence, until yesterday. ENT's have a guideline from their professional otolaryngology society, once every 1-3 months the first year, progressing a month further apart each year, up to five years, but have visited them much sooner depending on my medical need. A recent report says the palpable is just as good in detecting cancer as a scan, but I read otherwise, that a PET scan is much better in detecting cancer than a physical exam by a certain percentage, which I forget, but was quite high, and can detect cancers as small as 5mm.
As far as dentists, I would want to visit more than once a year, probably every three months. Radiation does damage directly to the teeth, gums, as well as by the dry mouth causing demineralization of the teeth, cavities. Mine were fine post treatment in 2011, for a while, but then started to get the white spots, demineralization, and now need all my teeth removed. Some dentists do remineralization of the teeth, but I didn't do that nor did I use a dental tray or prescription fluoride, even though I knew were available.