For an implant to be successful, there must be adequate bone available for proper placement. Since the bone and gums will shrink away once a tooth is removed, it is not unusual to have a situation where there is an inadequate amount of bone to place an implant. Simple techniques start with socket preservation where the dentist places a bone grafting material in the socket at the time of tooth removal. Even more predictable is placing a membrane over the graft material. This will allow the graft to heal undisturbed and has a very high rate of success. Once the bone height has shrunk, then a block graft needs to be done to give the bone more vertical. A block graft uses a piece of cortical bone that is obtained from another part of the body. Common areas are the mandibular ramus (the part of the jaw bone that lies behind the lower back teeth) or the mental symphysis (part of the chin). Once a block of bone has been harvested, then a flap of gum is peeled back at the donor site and the block is held in place with screws. Since the procedure utilizes bone from the same person, it doesn’t reject the graft. After allowing the area to heal for a few months, then the site will be ready for implant placement.
There are a number of techniques available to build up the jaw bone to give a good base for dentures. With autogenous bone grafts, a piece of bone is harvested from another part of the patient’s body. The most common area to get the bone from is the iliac crest. This is the part of the pelvis that lies above the hip joint. The body tolerates the bone graft since it is from the same person, so there is no risk for rejection. However, the surgical procedure that is utilized to obtain the bone can be somewhat debilitating. The feedback that I have gotten from patients is that the hip was much more uncomfortable than the mouth. Another technique is an allograft. This procedure utilizes cadaver bone. The sterilizing and screening techniques make for a wide margin of safety for cadaver bone. And the great news is there is not a need for an additional painful surgical site and long recovery period. Although the surgical success rate is good with allografts, they are still not as predictable as autogenous grafts (utilizing the body’s own tissue). After a few months of healing time, a denture can be safely constructed that should provide years of service.
To place dentures, there must be an adequate amount of jaw bone available to provide a place for the dentures to seat. Soft tissue is not firm enough to give proper support for false teeth. Alveolar bone is the bone that holds the teeth in place. That is its only purpose, so once the teeth have been removed, the body figures it has no more use for it and it resorbs (dissolves away). If the teeth have been missing for too long, then the available bone to hold a denture on is virtually nonexistent. That’s where bone augmentation helps. It is a surgical procedure to add bone to selected areas of the mouth. This will increase the height of the bony ridge and will give the denture more stability. There are a number of techniques available to add height to the jaw bone. These are particulate and bone graft substitutes. There are fancier membrane techniques where a thin membrane covers the graft material and allows the graft to heal undisturbed. There are autogenous bone grafts where a piece of bone form one’s own body is used and there are allografts which utilize cadaver bone for its source. The ridges can also be widened utilizing distraction osteogenesis. I will discuss each technique in more detail in Part II.