My original oral surgeon used a panoramic ("pano") X-ray - before the surgery, after the surgeries and annually after that. After 5 years of followups, I was pronounced cured and told I didn't need to come in for them anymore.
https://en.wikipedia.org/wiki/Panoramic_radiograph
My dentist spotted the regrowth on a pano X-ray - I hadn't had one in 10years, just the usual "bitewing" dental X-rays. Apparently my new dental insurance covered one pano every 4 years, so we did one.

Currently MD Anderson is having me get head CT scans (with contrast) since I am under active treatment and they can get a better view of exactly what's going on.

If I were in your situation, I would try for an annual pano Xray. I expect your PCP should be able to justify sending you for one due to the history of ameloblastoma and prior surgery.