Over a period of time, the jawbone associated with missing teeth shrinks away or reabsorbs. This process is called “disuse atrophy,” and it often takes away the bone needed to anchor an appropriately sized implant.
We now have the ability to reconstruct and replace bone where needed. This not only gives us the opportunity to place implants of proper length and width, but it also gives us a chance to restore functionality and esthetic appearance. Sufficient bone for these procedures can often be obtained quite comfortably from areas of the jaw adjacent to the deficient area.
Alternatively, in some instances, bone substitute materials can be used. When a tooth is removed, the bone at the extraction site tends to collapse inward and shrink over time. However, this bone can be maintained and even improved in terms of its volume and density by the addition of a processed mineral matrix to the site. This mineralized matrix resembles granules similar to grains of salt. It is packed into the site and sealed off from the oral environment. Over four to six months, the bone that was surrounding the root of the tooth replaces this matrix, resulting in the formation of a good quality, dense bone for future implant placement.
Sinus Augmentation (or Lift) Procedure
The maxillary sinuses are behind your cheeks and above the upper back teeth. Sinuses are like empty rooms that have nothing in them. Some of the roots of the natural upper teeth extend up into the maxillary sinuses. When these upper teeth are removed, there is often just a thin wall of bone separating the maxillary sinus and the mouth.
Dental implants need bone to hold them in place. When the sinus wall is very thin, it is impossible to place dental implants in this bone. The solution is a sinus lift bone graft. During this procedure, an oral surgeon enters the sinus from where the upper teeth used to be. The sinus lining is then lifted upward and donor bone is inserted into the floor of the sinus. Keep in mind that the floor of the sinus is the roof of the upper jaw. After several months of healing, the bone becomes part of the patients jaw and dental implants can be inserted and stabilized in this new sinus bone. Sinus lift grafts have an excellent success rate and make it possible for many patients to have dental implants, rather than loose-fitting dentures.
If enough bone between the upper jaw ridge and the bottom of the sinus is available to stabilize the implant, sinus augmentations and implant placement can sometimes be performed as a single procedure. If not enough bone is available, the sinus augmentation will have to be performed first; then the graft will have to mature for several months. Once the graft has matured, the implants can be placed.
In some cases, where teeth have been missing for extended periods of time, the residual ridge of bone may become too narrow and/or too short for implant placement. In these instances, small, carefully prepared and fitted grafts can be placed at the proposed implant sites to provide adequate bone thickness and/or height.
These grafting procedures may be performed separately or together, depending upon the individual’s condition. There are several areas of the body that are suitable for attaining bone grafts. In the maxillofacial region, bone grafts can be taken from inside the mouth, in the area of the chin, third molar region, or in the upper jaw behind the last tooth. In more extensive situations, a greater quantity of bone can be attained from the hip or the outer aspect of the tibia below the knee. Using the patient’s own bone for grafting procedures usually gives the best results.
In some cases, processed mineralized materials for bone grafting and implant placement are used. This bone is prepared from donors and used to stimulate the patients own bone to grow into the repair site. Synthetic materials can also be used to stimulate bone formation. Concentrated factors from the patients own blood are used to accelerate and promote bone formation in graft areas. These grafts are commercially prepared from animal donors, human donors, or other mineral sources.
These surgeries are performed in office surgical suites, usually using IV anesthesia to maximize comfort.