Bone Grafting

Missing teeth over a period of time can cause your jaw bone to atrophy, or resorb. This often results in poor quality and quantity of bone suitable for the placement of dental implants as well as long term shifting of remaining teeth and changes to facial structure. Most patients, in these situations, are not candidates for dental implants.

Fortunately, today we have the ability to grow bone where it is 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 aesthetic appearance.

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 to protect the bone graft, as well as encourage bone regeneration.

Major bone grafting is performed to repair larger 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 patient’s own bone. This bone is harvested from a number of different areas depending on the size needed.

Overview

Over a period of time, the jaw bone associated with missing teeth atrophies and is reabsorbed. This often leaves a condition in which there is poor quality and quantity of bone suitable for the placement of dental implants. In these situations, most patients are not candidates for the placement of dental implants.

With bone grafting we now have the opportunity to not only replace bone where it is missing, but we also have the ability to promote new bone growth in that location. 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 aesthetic appearance.

Types of Bone Grafts

Autogenous Bone

Autogenous bone, or autograft, is taken from your own bone, somewhere else in the body. The bone is typically harvested from the jaw, hip or lower leg bone. Autogenous bone is advantageous in that the graft material is your own live bone, meaning it contains living cellular elements that enhances bone growth, also eliminating the risk of your body rejecting the graft material since it comes from you. However, one downside to the autograft is that it requires a second procedure to harvest bone from elsewhere in the body.

Allogenic Bone

Allogenic bone, or allograft, is bank bone harvested from a cadaver, then processed using a freeze-dry method to extract the water via a vacuum. Unlike autogenous bone, allogenic bone cannot produce new bone on it’s own. Rather, it serves as a framework, or scaffold, over which bone from the surrounding bony walls can grow to fill the defect or void.

Xenogenic Bone

Xenogenic bone, or xenograft, is derived from non-living bone of another species, usually cow, pig or horse. The bone is processed at very high temperatures to avoid the potential for immune rejection and contamination. Like allogenic bone, xenogenic bone serve as a framework for bone from the surrounding area to grow and fill the void.

Both allogenic and xenogenic bone grafting have an advantage of not requiring a second procedure to harvest your own bone, as with autogenous bone. However, because these options lack autograft’s bone-forming properties, bone regeneration may take longer than with autografts, and have a less predictable outcome.

Socket Preservation Procedure

Removal of teeth is sometimes necessary because of pain, infection, deep cavity, periodontal disease or dental fracture. Socket preservation is used to preserve the bone and minimize bone loss after an extraction. With socket preservation, the tooth is removed and the socket is filled with bone or bone substitute. It is then covered with gum tissue or membrane which encourages your body’s natural ability to repair the socket. With this method, the socket heals, eliminating shrinkage and collapse of the surrounding gum and bone. The newly formed bone in the socket then provides a foundation for an implant to replace the tooth.

Bone Grafting for Dental Implants

After tooth extraction, if the walls of the socket are very thick, they will usually fill naturally with bone in three to six months. However, when the walls of your socket are very thin, this type of healing will not be as predictable. In these situations, bone grafting is often placed at the time of tooth extraction to help your body fill in the empty socket with bone. This step will maintain the width and volume of bone you will need for implant placement several months later.

There may be inadequate bone for implant placement if your tooth was removed many years ago and your bony ridge is extremely thin. In this case, bone graft can be placed next to the thin bone and allowed to heal for up to six months. After the graft has fused to your pre-existing bone, the ridge will be re-entered and the implant placed.

You may also need bone grafting if the sinus cavities in your upper jaw are very large, or very low, and extend into the tooth-bearing areas. This often occurs when teeth in the back of a person’s upper jaw have been removed many years before, and the amount of bone available for implant placement is limited. A “sinus grafting procedure” is then required. During this procedure, the membrane that lines the sinus will be located and elevated. Bone will then be added to restore the bone height and ensure that dental implants of an adequate length can be placed.

Ridge Augmentation

The alveolar ridge of the jaw is the bone that surrounds the roots of teeth. When a tooth is removed, an empty socket is left in the alveolar ridge bone. Usually this empty socket will heal on its own, filling with bone and tissue. Sometimes when a tooth is removed the bone surrounding the socket breaks and is unable to heal on its own. The previous height and width of the socket will continue to resorb.

Rebuilding the original height and width of the alveolar ridge is usually required for dental implant placement. Dental implants require bone to support their structure and a ridge augmentation can help rebuild this bone to accommodate the implant.

A ridge augmentation is accomplished by placing bone graft material in the resorbed alveolar ridge. Once the bone has healed, the alveolar ridge can be prepared for dental implant placement.

Sinus Lift

The maxillary sinuses are behind your cheeks and on top of the upper teeth. These sinuses are empty, air-filled spaces. 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.

The key to a successful and long-lasting dental implant is the quality and quantity of jaw bone to which the implant will be attached. A sinus lift, or sinus augmentation, can raise the sinus floor and allow for new bone formation. A sinus lift is one of the most common bone grafting procedures for patients with bone loss in the upper jaw. The procedure seeks to grow bone in the floor of the maxillary sinus above the bony ridge of the gum line that anchors the teeth in the upper jaw. This enables dental implants to be placed and secured in the new bone growth.

How is This Procedure Accomplished?

An incision is made on the premolar or molar region to expose the jaw bone. A small opening is cut into the bone, and the membrane lining the sinus is pushed upward. The underlying space is filled with bone grafting material. After the bone is grafted, the incision is sutured and the healing process begins. After several months of healing, the bone becomes part of the patient’s jaw and dental implants can be inserted and stabilized in the newly formed sinus bone.

If enough bone between the upper jaw ridge and the bottom of the sinus is available to sufficiently stabilize the implant, sinus augmentation 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 up to several months, depending upon the type of graft material used. Once the graft has matured, the implants can be placed.