Major and minor bone grafting
Over a period of time, the jawbone associated with missing teeth atrophies or is reabsorbed. This often leaves a condition in which there is poor quality and quantity of bone suitable for placement of dental implants. In these situations, most patients are not candidates for placement of dental implants.
|For a brief narrated overview of the bone grafting process, please click the image on the right. It will launch our flash educational MiniModule in a separate window that may answer some of your questions about bone grafting.
Today, we have the ability to grow bone where needed. This not only gives us the opportunity to place implants of proper length and width, it also gives us a chance to restore functionality and esthetic appearance.
Major Bone Grafting to repair major bone defects
Bone grafting can repair implant sites with inadequate bone structure due to previous extractions, gum disease or injuries. The bone is either obtained from a tissue bank or your own bone is taken from the jaw, hip or tibia (below the knee.) Sinus bone grafts are also performed to replace bone in the posterior upper jaw. In addition, special membranes may be utilized that dissolve under the gum. These membranes protect the bone graft and encourage bone regeneration. This is called guided bone regeneration or guided tissue regeneration.
Major bone grafts are typically performed to repair significant defects of the jaws. These defects may arise as a result of traumatic injuries, tumor surgery, or congenital defects. Large defects are repaired using the patients own bone. This bone is harvested from a number of different sites depending on the size of the defect. The skull (cranium), hip (iliac crest), and lateral knee (tibia), are common donor sites. These procedures are routinely performed in an operating room and require a hospital stay.
Minor Bone Graft and Ridge Preservation after extraction of teeth
There are many defects that limit the surgeons ability to place implants but do not require large volumes of bone to correct. Although natural bone can be used to successfully augment these defects, there are other alternatives available. The most common material used today is derived from cadaver cow bone. The bone is prepared by the combination of freeze drying, sterilizing and irradiating to eliminate the organic cow material. All that is left is the inorganic mineral components (calcium and phosphorus) that are provided in a granular form. This material can be placed in the existing bone defect or into an extraction site immediately following removal of the tooth. Human cells will grow out of the surrounding blood clot and turn the granules into human bone. This will prevent shrinkage of the bony ridge that usually accompanies an extraction or repair a defect that would prevent the placement of an implant. The same material can be placed around implants that have insufficient thickness of bone around them to properly anchor them in the bone. This material can be used alone or mixed with human bone depending on the specific situation. If no human bone is needed, that eliminated a second surgical site to harvest the human bone.
Sinus lift procedure
The maxillary sinuses are behind your cheeks and on top of the upper teeth. Sinuses are like empty rooms that have nothing in them. Some of the roots of the natural upper teeth in the molar region 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.
There is a solution and its called a sinus graft or sinus lift. The dental implant surgeon enters the sinus from where the upper teeth used to be. The sinus membrane is then lifted upward allowing donor bone and/or artificial bone to be inserted into the floor of the sinus. Keep in mind that the floor of the sinus is the roof of the upper jaw. After 6-9 months of healing, the bone becomes part of the patients jaw and dental implants can be inserted and stabilized in this new sinus bone.
The sinus graft makes it possible for many patients to have dental implants when years ago there was no other option other than wearing partial or full dentures.
If enough bone between the upper jaw ridge and the bottom of the sinus is available to stabilize the implant initially (5mm), sinus augmentations and implant placement can sometimes be performed as a single procedure (at the same time). If not enough bone is available, the Sinus Augmentation will have to be performed first, then the graft will have to mature for 6-9 months, depending upon the type of graft material used. Once the graft has matured, the implants can be placed as a second surgical procedure.
Ridge Augmentation and Ridge Expansion
If teeth have been missing for some time, the ridge will shrink in both height and width. In severe cases, the ridge will not be wide enough or high enough to place a dental implant. A bone graft is placed to augment ridge height and/or width to provide proper anchorage to surround the implant with healthy strong bone. After sufficient healing (6-9 months) the implants are placed during a second surgical procedure. A second technique involves mechanical expansion of the bony ridge. This is a technique used to restore the lost bone dimension when the jaw ridge gets too thin to place dental implants. In this procedure, the bony ridge of the jaw is literally expanded by mechanical means at the time the actual implant is placed. Bone graft material can be placed to supplement the thickness of the ridge around the implant. This is not helpful for increasing the bony height of dental ridges, only the width.
The inferior alveolar nerve, which gives feeling to the lower lip and chin, may need to be moved in order to make room for placement of dental implants to the lower jaw. This procedure is limited to the lower jaw and indicated when teeth are missing in the area of the two back molars and/or and 2nd premolar, with the above-mentioned secondary condition. Since this procedure is considered a very aggressive approach (there is almost always some postoperative numbness of the lower lip and jaw area, which dissipates only very slowly, if ever), usually other, less aggressive options are considered first such as ridge augmentation or placement of multiple short implants or a blade implant.
Typically, a portion of the outer section of the cheek side of the lower jawbone is removed in order to expose the nerve and vessel canal. Then the nerve and blood vessel are isolated in that area and gently moved out of the bone canal. The implants are carefully placed into the bony ridge extending through the vacated bone canal. Then the neurovascular bundle is released and placed back over the implants. The surgical access is refilled with bone graft material of the surgeons choice and the area is closed.
Continued Research and Surgical Innovations
Bone grafting and implant placement may be performed separately or together, depending upon the individual's condition. As stated earlier, 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 or the lower 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 at the knee. For significant bone defects, there is a real need to use human bone for adequate bone to be generated. In many instances it can be mixed with some of the artificial materials available to reduce the amount of human bone that has to be harvested.
In many cases, we can use allograft material to implement bone grafting for dental implants. This bone is prepared from cadavers and used to get the patients own bone to grow into the repair site. It is quite effective and very safe. Synthetic materials can also be used to stimulate bone formation. We even use factors from your own blood to accelerate and promote bone formation in graft areas.
These surgeries are performed in the out-office surgical suite under IV sedation or general anesthesia. After discharge, minimal activity is recommended for one day and limited physical activity for one week.
Website Design by PBHS Inc.
White Mountain Oral and Maxillofacial Surgery in North Conway, NH