Gingival grafts are for restoring the gums which were lost as a result of gumline recession, which is very common in people over 40 these days. The problem is that as gumlines recede, the nerve endings in the dentin tubules of the exposed root surfaces themselves become exposed, and are a source of sensitivity to hot/cold and can give great pain. Gingival grafts are where they take skin from other areas of the mouth and graft it to the gumline. The process is expensive, and all the grafts don't take, and you have to be careful for the first 6 weeks after the surgery, else they can be damaged.

In the long run, these are not a permanent fix, and will need to be re-done again in the future. If my memory serves correct, they're good for 5-7 years. One is far better off in eliminating the cause of the recession in the first place, but people habitually addicted to american ways of eating / cooking will find reversing gumline recession to be impossible without radical changes in their lives.