Grooves at Gumline, Recession and Sensitivity After Orthodontics

I went through a second set of full orthodontics a few years ago to basically un-do the squashing of my palette and cranium that the first set in high school had done. It was part of my chiropractic course and I think was helpful in that sense, though I have to wear a retainer to keep the new position. I am congenitally missing some teeth, 2 on top and 2 on the bottom, so I think because of that my teeth tend to move more.

I have a very hard time wearing the retainers because I'm quite sensitive to the cranial pressure they cause and the will often set off headaches for me. Even when I do wear them religiously at least 8 hrs a day, they still feel tight when I first put them in. If I don't wear them consistently, a couple of molars do not meet right in the back and then I get a lot of pain from chewing because the bite goes off.

Since I got those braces off a few years ago and began wearing the retainers, I have noticed some major sensitivity at the tops of most of my teeth, and at least half have very deep grooves up next to the gumline. I think the gums have receded somewhat. I'm very diligent with brushing and flossing, and always have been, but I think all this moving of my teeth - from the braces and also from the daily smaller movement when the retainers are in and out, is possibly what's causing this. On one tooth it's really extreme. It's like I'm damned if I do and damned if I don't with these retainers.

I got so tired of all the mouth work I have not been back to the dentist in probably close to two years, but I plan to see him again soon. I don't know what he can tell me or do for me at this point.

Once another dentist told me that the reason for sensitivity at the top of the teeth was grinding - i.e. pressure on the teeth and movement, not "over brushing" as I had been told before. Does anyone have info on this subject? It's pretty distressing that my teeth are in such bad shape after years of trying to hard to take care of them, and spending SO much money in the process! At this point I am less concerned about cosmetics than just keeping my teeth.