Before placement of an implant, it is sometimes necessary to create a stronger foundation. This is similar to the foundation of a home or building. Without a strong foundation, predictability and long-term success decreases. If you build on sand, or over a sinkhole, you can expect failure. With a good foundation, you can expect years of success.
Grafts can be from you, a tissue bank, from other living creatures or synthetically made. Most common grafts are actually small particles placed in the area the way salt is sprinkled on food. The area is then covered with a dressing, and is allowed to heal. The amount of time and number of grafts needed depends on the state of the site in its existing form.
The most effective and important time to graft is when a tooth is removed. This procedure is called socket or ridge preservation. Bone is lost immediately following removal as your body believes that bone is no longer needed since there is no tooth to be supported. Once lost, it becomes more difficult, and sometimes impossible, to recover. Placement of a graft material prevents the majority of this loss and preserves, or holds, the bone for implant placement, bridge support, or denture support.