How is Height of Bone Lost?
Bone surrounding teeth can lose height due to the following:
Why Graft?
Sufficient bone height is critical for implant support and long-term success. Short implants fail frequently, therefore they should be avoided. Instead, bone height can be developed allowing the placement of ideal length implants.
There are several techniques available for augmentation of bone in the vertical dimension based on location, degree of bone loss, and amount of bone augmentation needed:
Sinus Lift Bone Grafting:
Sinus lift bone grafting is performed when bone height is inadequate for implants in the back of the upper jaw. The back of the upper jaw has been a problem for dental implant placement for decades. All of the sinus cavities are located above the teeth and jawbone. They tend to enlarge after tooth loss or removal, leaving very little residual bone for implant placement and stability. In the early 1990s, a technique was discovered that allows elevating the floor of the sinus cavity in a small region and adding sufficient bone for implant placement. This is accomplished without going into the sinus itself, or changing the way that it functions.
This procedure allows for ideal implant placement with success rates equivalent to placement in non-grafted bone. Often, the graft can be done at the same time as implant placement. The implants are then restored (replacement teeth placed) in approximately six months. If very little bone is present to start, the graft will need to be done first, with the implants placed after the initial six months of healing. The implants then need another six months to bond to the newly formed bone before replacement teeth can be placed.
Onlay Bone Graft:
Onlay bone grafting is indicated where there is minor to moderate bone deficiency at the top of the ridge resulting in inadequate height. Onlay graft, however, is not as predictable in vertical deficiencies as it is in horizontal deficiencies.
Distraction Osteogenesis:
Distraction osteogenesis is used when there is severe loss of bone height. This approach allows bone generation by gradually “stretching” the existing ridge. This is a very predictable technique and may be combined with onlay grafting for width deficiencies in patients with three dimensional bone loss.
Bone Regenerative Techniques:
In some vertical defects, it may be possible to develop new bone using regenerative bone materials instead of actual bone obtained from another part of the body.