Why Bone Grafting?

In many instances, a potential implant site in the upper or lower jaw does not offer enough bone volume or quantity to accommodate a dental implant of proper size or in the proper place. This is usually a result of bone resorption that has taken place since one or more teeth (if not all) were lost. Bone Grafting procedures usually try to re-establish bone dimension, which was lost due to resorption. A bone graft normally takes at least six months to heal before a dental implant can be placed into it. There are times also that multiple grafts may be needed to produce the amount of bone needed. This is dependent on a persons health and amount of bone being grafted.

Years ago the lack of bone posed a considerable problem and sometimes rendered implant placement impossible. Today, however, 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 the aesthetic appearance and functionality of natural teeth.

Grafting Material:

With respect to the Bone Graft material used, we have to differentiate between several choices. All materials can be categorized into five different categories:

• Autograft or autogenous bone graft
• Allograft or allogenic bone graft
• Xenograft or xenogenic bone graft
• Alloplast or alloplastic bone graft

The Autograft is considered the Gold Standard. It is defined as tissue transplanted from one site to another within the same individual. It is basically your very own bone taken from a donor site and placed somewhere else in the body, into the recipient site. The best success rates in bone grafting have been achieved with autografts, because these are essentially living tissues with their cells intact. There is no immune reaction and the microscopic architecture is perfectly matched. The only disadvantage of the autograft is that it has to be harvested from a secondary site in your body, which usually means more morbidity and a more complicated surgery overall. For most grafting purposes confined to Oral Implantology we can use another part of the jaw (e.g. chin or back portions of jaw) as an acceptable donor site. This way, we stay surgically inside the mouth and avoid any extraoral wounds and scarring.  Often Dr. Bauer will simply "shave" some autogenous bone with a specified device for this. This alows inclusion of autogenous bone in addition to other materials in a simple and safe way.

The Allograft is defined as a tissue graft between individuals of the same species (i.e., humans) but of non-identical genetic composition. The source is usually cadaver bone, which is available in large amounts. This bone however has to undergo many different treatment sequences in order to render it neutral to immune reactions and to avoid cross contamination of host diseases. These treatments may include irradiation, freeze-drying, acid washing and other chemical treatments. In the U.S. virtually all donors are being prescreened for infectious diseases before their bone is even accepted into the tissue banks. After that the processing of the bone would eliminate virtually any chance of cross-infection. To read more and inform yourself on the processing of donor bone products. Go to The American Association of Tissue Banks http://www.aatb.org/

The Xenograft is defined as a tissue graft between two different species (i.e. bone of bovine origin). Tissue banks usually choose these graft materials, because it is possible to extract larger amounts of bone with a specific microstructure (which is an important factor for bone growth) as compared to bone from human origin.

The Alloplast usually includes any synthetically derived graft material not (coming) from animal or human origin. In Oral Implantology this usually includes Hydroxyapatite or any formulation thereof.

A favorite product of Dr. Bauer's is  Puros and C-Graft. C-Graft is a product derived from Sea Algae .

Each of the bone graft materials is usually developed with a specific purpose or advantage in mind. Some claims made by tissue banks about a certain bone graft material may sometimes have to be taken with a grain of salt, until independent research can verify those claims. The main purpose of using the latter three of the above graft materials is usually to avoid a secondary surgery for harvesting autogenous bone. Your surgeon will make a decision with respect to the bonegraft material, based on your individual needs and the latest research in that field.

Sinus Augmentations

One of the most frequently applied grafting procedures is the Sinus Augmentation. This procedure is restricted only to the upper jaw.

As we get older our sinuses grow larger in volume and literally take away valuable bone from the jaw ridge as shown below on the x-rays. This is not a pathological condition, on the very contrary, it happens to almost every one. This process is called Pneumatization of the Para-nasal sinuses.

Once teeth are lost in that particular area it makes it difficult if not impossible to place endosseous implants in that area. For this particular problem a grafting method was developed to literally raise the bottom of the sinus back up, graft bone underneath and, thus create enough space for one or more dental implants.

This procedure has been performed successfully for over two decades now and is considered an accepted and predictable method of bone grafting. The grafting material being used can be of either of the above mentioned categories. Again, autogenous bone will give you the best and fastest results. However, it would take a considerable volume of bone (5cc to 10cc per side) to perform a typical sinus augmentation; usually more than can be harvested from intraoral donor sites. Therefore, we sometimes downsize to an alloplast or xenograft or a combination (sometimes mixed with a little autograft) and take into account a longer maturation time.

Sinus Augmentations and implant placement can sometimes be performed as a single procedure if enough bone between the upper jaw ridge and the bottom of the sinus is available to stabilize the implant well. 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 (depending on the graft material used). Once the graft has matured the implants can be placed.

Sometimes a "Summers Lift" can be performed where the sinus membrane can be simply pushed up in a very conservative manner.

Source: Robert Gougaloff, DMD

Onlay Grafts

This type of grafting procedure is designed to re-establish bone, which has been lost in a particular area due to resorption (which again, has been brought on by previous tooth loss in that area).  A piece (or several pieces) of bone is attached to the site with the bone deficiency. Then the area is closed up and after a certain healing and maturing period, this piece of bone will eventually be incorporated into the host bed and become solidly fused, so that at a later time implants can be placed in that same area.

Larger areas of resorption will need to be augmented with more pieces of  bone. For those cases we need to go to the patient’s hip or tibia to get more quantity of bone. This, however, is not a very frequent occurrence, unless the patient had lost all of his or her teeth for a long period of time (several decades) and bone resorption is very severe. At that point, however, other implant modalities can sometimes be chosen to circumvent this rather aggressive surgical approach.

Source: Robert Gougaloff, DMD