I have a student with a really nice Selle Francaise mare who cribs....badly. She did try the rings. While they worked, initially, her gums started to recede too much and they were removed. So, in this case they failed due to secondary problems.
I would get your horse scoped to check for ulcers. They tend to be one cause for cribbing.
If she doesn't have them, a collar is still the only solution. I would get several different styles and change them often. When you swap, thoroughly clean and condition the one removed so that it is soft and ready the next time it is used. Every collar will rub. Different collars fit differently, so the rubs will be different keeping them from progressing.
Did the gums recede because of the rings, or from something else? That definitely sounds like a serious side effect!
My vet did suspect ulcers when I first got him (from the cribbing, girthiness, and being underweight). Per her advice, I've been feeding him a grain-free diet, supplementing U-Gard, and giving him a slow feeder net whenever I'm there (unfortunately the stable hands won't refill it for me). He's up to a healthy weight, is only a little grouchy while being girthed, and no longer cribs while he's eating, which are all very nice improvements. From what I understand, though, long-time cribbers almost always continue cribbing even after the initial underlying cause is gone.
Rotating through different styles sounds like an excellent idea. While I had considered buying the Dare cribbing collar because it doesn't have a front strap, I hadn't really thought of keeping multiple ones around to rotate through them.
Well, I haven't had any experience with crib biting... But I did have braces once, and that really hurt... I can imagine the rings aren't very comfortable. I also think that the horse might start cribbing again once they're removed.
Is there a reason you can't keep his collar on? Have you tried that crib stop stuff?
Hope it works out (:
Yeah, I had braces when I was in high school, and it definitely wasn't fun. I imagine that cribbing rings are a different style of pain, though
A lot of the articles make it sound like after the initial soreness from piercing the gums is done, the horses ONLY experience discomfort when they're cribbing. I've heard the same thing about cribbing collars, but I can't imagine that having a tight strap on your head with a tab in your throat all the time is very comfortable, either.
I haven't tried the crib stop stuff, mostly because he gets rotated through different paddocks for turnout each day, so it's not very practical. In his stall, he mostly cribs on his waterer and I'm hesitant to put anything on it that might get into the water and discourage him from drinking.