Constructing a new set of dentures is not always as straight forward as taking a quick impression of one’s mouth. First, the dentist must check the tissues for any pathology. It is certainly not a good idea to build a denture over a tumor or cancer. The next thing to check is the condition of the ridges of the gums themselves. If there is inadequate bone to allow for good retention and stability of a denture, then a bone graft may need to be considered. Artificial bone substitutes, cadaver bone, or pieces of the patient’s own bone can be placed under the gums surgically to add enough bulk to comfortably wear a denture. If there are bumps of bone called tori or severe bony undercuts that rigid plastic could not snap around, then they need to be surgically removed. The dentist peels a flap of gum tissue that is over the bony prominence and grinds the offending piece of bone off and smooth the area. In other cases, there could be flabby, moveable tissue or even extra folds of gums which would make a denture unstable. This would also have to be surgically removed. By properly preparing a good gum foundation, a very well fitting set of dentures can be constructed.
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.