Gums Receding around Implant Site for Fixed Upper Bridge: What is My Next Step

About two years about I had to get my front 6 upper teeth pulled and have a fixed bridge put in. Luckily, we were able to do it without the bar, and it’s retained on four mini dental implants. At the same time, I had two mini implants put in on the bottom, as I already had a lower denture. About a year ago, I started to notice that my upper gums were slowly receding from the implants on the outer side, around the screw-type threaded part.

My dentist said it was nothing to worry about and that it would definitely stop when it got to the bone…. Well, it has nearly progressed up to the top now and, as you can imagine, I am quite alarmed at this. On the lower implant retained denture, I’ve noticed (also over the last year) that the gums have gone down a bit to expose more of the abutment. The lower ones don’t bother me as much, since my gums and bone loss are the reason I had to give up and get implants in the first place (history of 2 baby teeth and then the adult teeth growing in hollow, very narrow bone ridges, etc.)…what does worry me is the fact that I had to give up the crowns I had on top and get the upper bridge BECAUSE my gums were receding from them and then he didn’t seem concerned about their retreat from the implants… However, the implants are still very firmly in place and there is no pain or sensitivity. There has been no diet change since I have gotten them. I don’t dig in the uppers, but I do make sure there is no food stuck in them after every meal (a pet peeve since I’ve gotten them), I clean around the lower abutments very well three times a day but I’m careful not to irritate the tissue. I put a ton of time and money into all of this and am terrified to lose them. Two questions: How common is this? And what is the next step if my gums continue their trek north? Any help you could offer would be appreciated.