Bone Augmentation

For dental implants to be successful, the jawbone must have enough bone to support them. You may not have enough bone because of tooth loss from periodontal (gum) disease, injury or trauma, or a developmental defect. If your jaw is too short (up and down), too narrow (side to side), or both, you will need a procedure to add bone to your jaw before implants can be placed.

Bone augmentation is a term that is used to describe a variety of procedures that are used to "build" bone so that dental implants can be placed. These procedures typically involve grafting (adding) bone or bonelike materials to the jaw, and waiting for the grafted material to fuse with the existing bone over several months.

There are several different procedures that can be used for bone augmentation. Your dentist will select a procedure depending on the type, location and number of implants to be used.  If you need a bone graft, it is important that you and your dentist discuss all of the options available to you.

After a bone-augmentation procedure, dentists usually wait 6 to 12 months before placing implants, although some dentists may place them sooner.

Where Does the Bone Come From?

Most bone-augmentation procedures involve the use of bone grafts. The best material for a bone graft is your own bone, which most likely will come from your chin or ramus (the back part of your lower jaw). If your oral surgeon cannot get enough bone from these areas, he or she may need to get bone from your hip or shin bone (tibia) instead. The hip is considered to be a better source because the hip bone has a lot of marrow (soft tissue within the bone), which contains bone-forming cells.

If you don't like the idea of having bone removed from your body to be placed in your jaw, there are other options available to you. Your dentist can use materials made from the bone of human cadavers or cows. There are also synthetic materials that can be used for bone grafting. While most dentists prefer using a person's own bone, possibly in combination with other materials, the choice is yours. You should discuss your options and their risks and benefits with your dentist before any procedures are done.

A Typical Bone-Augmentation Procedure

In a typical situation, a patient has lost a single tooth and wants to have it replaced with a crown supported by a dental implant. However, the tooth has been missing for several years and there is not enough bone to support the implant. In this case, bone taken from the patient's chin can be used to "rebuild" the lost bone so that it can support an implant. This type of procedure would be done in a dentist's office.

Local anesthesia will be used to numb the area where the bone augmentation is needed (recipient site) as well as the area from where bone will be removed (donor site). The DSI specialist first will make an incision (cut) in the gum where the implant will be placed to determine how much and what type of bone is needed.

He or she then will make an incision in the gum below the lower front teeth to expose the chin bone. A block of bone will be removed from the chin along with any bone marrow. The specialist will fill the spot where the bone was removed with another type of bone-graft material, and will cover this with a membrane (thin film of tissue) to keep soft tissue from filling the space as it heals. The incision then will be stitched closed.

To place the removed bone in the recipient site, the DSI specialist first will drill little holes in the existing bone to cause bleeding. This is done because blood provides cells that help the bone heal. The block of bone that was removed from the chin will be anchored in place with titanium screws. A mixture of the patient's bone marrow and some other bone-graft material will then be placed around the edges of bone block. Finally, the DSI specialist will place a membrane over the area and will stitch the incision closed.

After a bone-augmentation procedure, you will be given antibiotics, pain medication and an antibacterial mouthwash. You will be asked to avoid certain foods, and will be told how to avoid putting pressure on the area while it heals. If you wear a denture, you may not be able to wear it for a month or longer while the area heals. If you have natural teeth near the bone graft, your dentist may make a temporary removable bridge or denture to help protect the area.

The bone graft will take about 6 to 12 months to heal before dental implants can be placed. At that time, the titanium screws used to anchor the bone block in place will be removed before the implant is placed.

Building Up Bone for Several Implants

Many people are missing several teeth and need several implants. If bone needs to be built up to support several implants, a lot more bone-graft material will be needed than if a single implant is being placed. If you are having several implants placed and choose to use your own bone for a bone-graft procedure, the bone probably will have to be taken from your hip, shin or another site. This type of procedure is done in the hospital under general anesthesia, and requires an overnight stay.

Success of Bone Grafting

The success rate for bone grafts in the jaws for the purpose of placing dental implants is very high. However, there is always a chance that the bone graft will fail, even if your own bone was used. Bone grafts are not rejected like organ transplants. When they fail, it is usually because of an infection or because the grafted bone wasn't stabilized and has come loose from your jaw. Dentists don't know why some bone grafts fail, but they do know that certain people — such as those who smoke and those with certain medical conditions — have a higher risk of graft failure than others.

A failed graft will be removed. Once the area has healed, your dentist can place a second graft.

Other Types of Bone-Augmentation Procedures

In addition to bone grafting, many other types of procedures can be used to build bone so that implants can be placed.

One type of bone-augmentation procedure, called a sinus lift (or elevation), increases the height of your upper jaw by filling part of your maxillary sinus (the area above your jaw on either side of your nose) with bone. This is done when there is not enough bone to allow implants to be placed in the back part of the upper jaw.

A ridge expansion is a type of bone graft that can be done when the jaw is not wide enough to support implants. Your oral surgeon uses a special saw to split the top of the jaw ridge, and then packs graft material into the newly created space. Some dentists will place implants directly after this procedure. Others will wait several months for the ridge to heal. This procedure can be done in the dental office under local anesthesia.

One of the newest procedures for augmenting areas of bone is called distraction osteogenesis. This procedure originally was used for lengthening the bones of patients with abnormally short legs. It now has been adapted for use in the mouth. A surgeon makes cuts in your jawbone to separate a piece of bone from the rest of the jaw. A titanium device inserted into the jaw with pins or screws holds the piece of bone apart from the rest of the jawbone. Over time, the space between the piece of bone and the jawbone is widened slightly by unscrewing the device, and the area between the pieces gradually fills in with bone. "Distraction" refers to the process of separating the two pieces of bone, and "osteogenesis" refers to the forming of new bone. Distraction osteogenesis is used more often to make the jawbone taller, but it can be used to increase the bone in any direction. The procedure is becoming more common.

Nerve Repositioning

A nerve called the inferior alveolar nerve runs through the lower jaw. This nerve gives feeling to the lower lip and chin. In patients who have lost significant amounts of lower jawbone, it may not be possible to place implants without damaging this nerve. To address this problem, an oral surgeon can drill a small window in the bone and move the nerve to one side. The implants then can be placed through the bony canal previously filled by the nerve. This technique is not used very often because it is possible to damage the nerve just by moving it.