Sinus Augmentation Surgery

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, as you can see on the right image above. 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. Compare the two x-rays below.

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 form intra-oral donor sites. Therefore, we sometimes downsize to an allograft, alloplast or xenograft or a combination (sometimes mixed with a little autograft) and take into account a longer maturation time. An autograft takes approximately 4 to 6 months to mature in the sinus, an allograft, alloplast or xenograft may take 9 months or more.

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.

Grafting Materials

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 – 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 (i.e., 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. Sometimes, however, when there is not enough bone volume available intraorally, we have to get bone from other parts of the body (usually your hip bone or your tibia (shin) bone) or even from a bottle – alloplast, allograft, or xenograft.

Allograft or allogenic bone graft – 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.

Alloplast or alloplastic bone graft – 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.

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 four 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 bone graft material, based on your individual needs and the latest research in that field.

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