The zone of gum tissue is the defense mechanism of your mouth. It is this tissue that maintains the seal of the gum to the tooth, preventing plaque from getting under the gum and destroying the underlying bone support. When this tissue is thin or completely absent, this defense mechanism is no longer effective.
Studies have shown that inadequate zones of gum tissue do not break down in a regular pattern. Usually, it stays stable for a non-specified period of time. Then, once it has been irritated by some factor, it breaks down and recedes significantly down the root.
The irritant that causes this recession may be a toothbrush, hard food, a tooth filling, dental braces, a dental crown, gum infection or other factors. Once this tissue has receded and the tooth looks longer, it is very difficult to place new gum tissue back to the original height.
A gum graft is performed in order to correct this problem, protect the underlying bone and prevent the gum tissue from receding even further. The goal is to create a new zone of defense, or gum tissue. The longer tooth, caused by recession, is extremely difficult to cover up again once it is exposed. There are, however, special circumstances and procedures where exposed roots can be covered.