Kristin,
For quite awhile, I've been continuing to see my dentist for very routine things, but going to an oral surgeon or periodontist for anything more complex, because of my radiation history. On my most recent visit to my oral surgeon, he recommended that I have most of my followups with the periodontist (rather than the dentist). I'm 54 and still have all of my original teeth, but I'm beginning to have some problems with the bone at the back of my mouth, and he wants this monitored very closely.
I see that you're on the Cape -- I don't recall if you mentioned where your mom was treated, but if it was in the Boston area, it's probably worth checking with her oncologists there to get a recommendation on a dental professional.
Cathy