Gum recession can be caused by brushing the wrong way, which is what happened to me,(side to side or up down- a circular motion is best I was told, or by brushing too hard and you shouldn't brush for more than 2 minutes. I had some recession at the top of my teeth near the root which was quite painful to point that the dentist who treated it said he couldn't believe I was living with it.
Anyway, he put some enamel near the root and it helped the pain a great deal- I use pro-namel sensitive toothpaste once a day now and I changed my brushing patterns. I also recommend Dr. Katz's thera breath toothpaste and rinses: specifically the periodontal rinse if you have this problem etc. His products don't have the harsh soaps/detergents that normal toothpastes have which dry your mouth out and which can cause decay. Of course bg control is really important too.
I recently started using a water floss device now which works really well.
I had a tmj/jaw injury and I wore so many devices, none of which helped me. I eventually threw them all away.