What is bone graft material, where does it come from and is it harmful?

In dentistry, the proper name for this material is a bone graft. Its powdery look comes from the fact that it is mostly used as small granules; it also comes as blocks and as a paste. Its job is to fill volume that has been lost from the jawbone and to prepare the ground in which new bone will form in that space. That is why bone graft material is not a treatment on its own; it is usually an intermediate step, carried out before an implant or in the same session as the implant.

What the material does in the body is like scaffolding. Over time, blood vessels and bone-forming cells move into the spaces between the granules, and your own bone grows along this scaffolding. Beyond that, your own bone also carries living cells and growth signals, so it can start bone formation by itself; in the other materials this property is either absent or very limited. This is where the main difference between the sources comes from.

The first source is your own bone; dentists call this an autograft. Small amounts are usually taken from the same mouth, from the chin or from the area behind the lower molars; for large defects, more distant sites such as the hip may come into it. There is no question of the immune system reacting to this material, and biologically it is the most effective source. The trade-off is a second wound: pain, swelling and, rarely, numbness can occur where the bone was taken. Your own bone also remodels faster than the other materials, and some of its volume may be lost over time.

The second source is bone taken from another person (an allograft). It is prepared in tissue banks, going through donor screening and processes that reduce the risk of transmitting infection; it comes frozen, dried or with some of its minerals removed. The third source is animal bone (a xenograft). In dentistry the most common is bovine (cattle) bone; there are also products derived from pigs and horses. In these materials the organic part is removed with high heat and chemical processing, leaving the mineral framework of the bone. Bovine-derived granules resorb very slowly, and some of them can still be seen inside the new bone years later; when it comes to preserving volume, this is a desirable property.

The fourth source is synthetic materials (alloplasts): laboratory products such as hydroxyapatite, tricalcium phosphate and bioactive glass, which mimic the mineral structure of bone. They come from no living donor and no animal, and how quickly they resorb varies by type. Whichever graft is used, in most procedures it is covered with a collagen membrane. The membrane stops the fast-growing gum tissue from collapsing into the graft and buys the bone time. It is worth knowing that a large proportion of collagen membranes are also derived from pigs or cattle.

Which material is chosen depends on the size, shape and location of the defect. In an extraction socket whose four walls are intact, the choice is wide; in areas where the bone needs to be built out beyond its existing boundaries, the work gets harder. The Cochrane review of bone augmentation techniques before implants reports that it is not clear which technique is better, and that complications are common, particularly when bone is built up vertically. The same review also notes that some bone substitutes may be associated with fewer complications and less pain than taking bone from elsewhere in the body.

The distinction below is a general framework. Whether it is needed in your case is shown by the examination and, in most cases, a 3D CBCT scan; two patients who arrive with the same sentence can get different answers.

The sequence below describes a small to medium-sized graft placed in an extraction socket or around an implant. Sinus lifts and block grafts are more extensive procedures.

1. 1

   Imaging and planning

   The size and shape of the defect are measured with a 3D CBCT scan. Which material will be used, whether a membrane is needed and whether the implant will go in during the same session or later are decided on the basis of these images. This is the right moment to ask where the material comes from.

2. 2

   Numbing the area

   The procedure is usually done under local anaesthetic; for anxious patients, sedation can also be discussed. During the procedure you feel pressure and vibration, not pain.

3. 3

   Opening and cleaning the area

   The gum is lifted so that the bone surface can be seen. Any inflamed tissue left in the extraction socket is removed completely; whether the graft takes depends largely on this step.

4. 4

   Placing the graft

   The granules are placed in the area where bone is missing; if your own bone is to be used, it is first taken from a nearby site. If needed, the graft is fixed in place and covered with a collagen membrane.

5. 5

   Stitches

   The gum is stitched so that it closes over the graft without tension. This detail matters: a wound closed under tension tends to open, and the graft can become exposed.

6. 6

   Waiting, and a follow-up image

   Stitches are usually removed in the first or second week. The graft takes months to mature; before moving on to the implant, a new image is taken to check whether enough bone has formed.

When you are told bone is missing, a graft is not the only option. Which route is suitable is decided by the location and size of the defect; none of the options below works in every jaw.

Bone grafts have been widely used for many years and are considered safe in the right situation. Being safe does not mean being free of risk; the points below should be discussed with you before the procedure.

The sequence below is a general framework for a graft placed in an extraction socket or around an implant. With a sinus lift and with large grafts, the timescales are longer.

1. The first three days

   Swelling and tenderness usually peak on the second or third day, then go down. Cold compresses, taking the medicines you have been given regularly and eating soft, lukewarm food are the basis of this period. Do not probe the area with your tongue or rinse vigorously.

2. The first two weeks

   The stitches are removed during this period. Avoid chewing on that side. If the graft was placed at the back of the upper jaw or in the floor of the sinus, you will be asked not to blow your nose hard and not to use a straw. Smoking is one of the things that most impairs healing during this period.

3. 3–6 months

   The graft matures during this time. If a conventional implant is to be placed at a separate stage, the bone is checked with a new image at the end of this period. With large-volume augmentation and with a sinus lift, the wait can be longer.

4. After the implant

   Bone created with a graft needs looking after once the implant has been placed, just like any other bone. If the gum around the implant becomes inflamed, this bone can be lost too; regular cleaning and check-ups are what decide it.

Bone graft material is not a single item; it is a procedure whose scope varies a great deal with the material used, the amount and the size of the procedure. There are no figures on this page; the scope becomes clear after the examination and imaging. These are the things that determine it:

Where the material comes from

Your own bone requires an additional surgical site; donor, animal and synthetic materials are ready-made products and vary by manufacturer. You have the right to ask from the outset which product will be used and where it comes from.

The size of the defect

Filling a single extraction socket and building up part of the jaw vertically are not the same job. The amount of material used and the length of the procedure increase with the size of the defect.

Membrane and fixation

Whether a collagen membrane, a titanium mesh or fixing with small screws is needed changes the scope of the procedure directly.

Number of stages

Are the graft and the implant done in the same session, or are two separate operations needed months apart? This decision, more than any other, determines the number of visits and the total time.