What is Bone Grafting?
When teeth are lost, the alveolar bone that previously housed them begins to dissolve away in a process called resorption. Depending on the rate of resorption, the remaining bone may be insufficient to replace the missing tooth with a dental implant. If the missing tooth is to be replaced with a fixed bridge, the prosthetic replacement tooth (pontic) may look artificially large if the bone and gum tissue (gingiva) have resorbed significantly.
One solution to this dilemma is to graft new bone onto the site. This process is sometimes referred to as site development, which refers to the fact that proper bony and gingival contours need to be re-established before ideal tooth replacement can be done. There are several ways of performing a bone graft.
First, bone resorption can be prevented by packing the tooth socket with powdered bone graft material (called a socket graft, or ridge preservation) at the time of tooth removal.
Bone grafting can also re-establish the height (by a limited amount) and width of alveolar bone that has already been lost following removal of a tooth. A block cortical graft involves attaching a solid piece of bone to the deficient area, and attaching it with fixation screws while it integrates into position over several months.
Roots of the upper back teeth often project up into a hollow chamber inside the cheek bones, called the maxillary sinus. When any of those teeth are lost, bone may resorb from the sinus floor, as well as the other walls of the tooth socket. It can usually be regenerated in a procedure known as a sinus lift or sinus elevation.
Bony defects sometimes occur around teeth with multiple roots. Such areas can often be treated by guided tissue regeneration (GTR).
The process of Bone Grafting
There are two common bone graft techniques for assuring an adequate volume of bone at the site of a missing tooth: ridge preservation with a tooth socket graft is used to prevent bone loss; and block cortical graft procedures are used to widen narrow bony ridges where resorption has already occurred. Other types of bone grafting procedures performed in dentistry utilize similar techniques, including the commonly prescribed sinus elevation (sinus lift) procedure. The goal of a sinus elevation is the same: to provide enough bone to place dental implants in the upper jaw, where they would otherwise be sticking up into the air space of the maxillary sinus.
Bone grafting materials
For most bone grafting procedures, powdered bone is used, at least to some extent. Human bone powder from a tissue bank (allogenic graft material) is used most commonly in the United States. After the bone is harvested from the donor, it undergoes a series of rigid sterilization and purification procedures. It is reduced to small particles, packaged in sterile vials and shipped to the dentist. The lot is traceable to the donor through the entire process by unique tracking numbers. An alternative bone material is bovine (cow) bone. Some dentists, especially those outside the United States, prefer to use synthetic materials.
Before the procedure
If you take blood thinning medications or drugs that inhibit platelet aggregation, particularly if your bleeding time is elevated (as measured using the INR value), your dentist and/or physician may require you to suspend those medications temporarily to have any oral surgical procedures, including bone grafting. This is due to the possibility for prolonged bleeding from the surgical area.
If you are anxious about dental procedures, your dentist may recommend sedating you for the procedure. There are several methods of relaxing patients for dental treatment, including oral anti-anxiety pills; inhaled anti-anxiety medication like nitrous oxide; and intravenous anti-anxiety medication. Your dental plan may not pay benefits toward sedation.
You should have a good idea what the process involves after reading this material. Your procedure may vary from that described, and you should discuss specific details with the dentist. Bone science and tissue engineering are rapidly developing areas of dentistry and medicine, and it is possible that new techniques may be available which may be of benefit to you.
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