This page describes several methods of Bone Grafting.  These procedures are usually necessary if there is not enough bone available to place dental implants or if any vital anatomy is in the way.  Several modalities of Bone Grafting as they relate to Implant Dentistry will be discussed.  Some of the picture links will underline these discussions with a graphic representation of the procedure, however, these images are mostly surgical images and may be very graphic in nature!  Also, it may take considerable time to load all the images if you are on a slower modem connection.

Why Bone Grafting?

Today Bone Grafting procedures have become almost an integral part of Implant Reconstruction.  In many instances, a potential implant site in the upper or lower jaw does not offer enough bone volume or quantity to accommodate a Rootform 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.

If you click on the button below, you can see a succession of lower jaws undergoing several stages of resorption:

Many years ago the lack of bone posed a problem and sometimes implant placement was impossible because of that.  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 (and for Rootform Implants we always try to go for “as long and wide as possible”), it also gives us a chance to restore the esthetic appearance and functionality better.

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 allogeneic bone graft

• Xenograft or xenogenic bone graft

• Alloplast or alloplastic bone graft

• Growth Factors, such as Bone Morphogenic Proteins (BMPs)

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 Implant Dentistry we can use another part of the jaw (s.a. 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 shin bone, since these are the most accessible areas to get larger quantities of bone.

The Allograft is defined as a tissue graft between individuals of the same species (s.a. humans) but of nonidentical 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 US 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.

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 stemming from animal or human origin.  In Implant Dentistry this usually includes Hydroxyapatite or any formulation thereof.

The Growth Factors are natural proteins found in our bodies that stimulate growth of certain tissues.  With respect to bone, genetic engineers have been able to isolate and clone Bone Morphogenic Proteins (BMPs), which have been shown to induce tremendous bone growth in many animal and recently human clinical studies.  BMP’s may very well become a potential substitute for autogenous graft material for certain applications in the future; however, these substances still need to pass FDA approval.

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 bonegraft material, based on your individual needs and the latest research in that field.

We will describe several types of bone grafting procedures below.  Each of these modalities will be discussed and supplemented with images.  If you want to see these images, click on the “Show Images” buttons.  Some of these images, however, are surgical images and very graphic in nature.

Since we are going to discuss a variety of different grafting techniques, we have placed "Shortcut Links" below, if you know exactly which type of grafting technique you would like to get information on:

• Sinus Augmentation

• Onlay Graft

• Ridge Expansion

• Nerve Repositioning

• In-Situ Grafting

Sinus Augmentation:

One of the most frequently used grafting techniques is the Sinus Augmentation.  This procedure is only used, when there is a deficiency of bone in the upper jaw.

As we get older our Para- Nasal 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 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 intraoral 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.

A video of a Sinus Augmentation procedure can be seen on Dr. Gougaloff 's Sinus Augmentation Video.

Onlay Graft Procedure:

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).  For our purposes this procedure is considered an autogenous graft procedure.  A piece (or several pieces) of autogenous bone (usually from the chin or the very back of the lower jaw)  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 autogenous 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 (Subperiosteal Implants, Ramus Frame Implants) to circumvent this rather aggressive surgical approach.

Below you can see on a stone model a ‘before’ and ‘after’ image of an area in a patient’s upper jaw that underwent an Onlay Grafting procedure.

If you click on the "Show Procedure" button below, you can see the entire surgical progression of this case, but be aware of the loading times and the graphic content of the material.

A video of a block harvest procedure can be seen on Dr. Gougaloff 's Block Graft Video.

Ridge Expansion Procedure:

This is a technique used to restore lost bone dimension when the jaw ridge gets too thin to place conventional Rootform Implants.  This may actually not necessarily be considered a bone grafting technique in the strictest sense as we will se below.

In this procedure, the bony ridge of the jaw is literally ‘expanded’ by mechanical means.  A series of “Expanders” (in cross-section round or D-shaped metal rods of successively increasing diameter) are being forced into the chosen implant site.  This is accomplished by ‘tapping’ these expanders into the ridge with a surgical mallet.  This will compress the inner spongy part of the bone and, bulge out the outer cortex, if properly done.  At this point an appropriate implant can either be placed immediately into the created socket or one can place a bone graft into it first and let it mature for a few months before placing the implant (at this point it can actually be considered a Bone Grafting procedure since we are adding graft material).

Click on the "Show Procedure" button below to see a series of images illustrating this procedure.

A video of a Ridge Expansion procedure can be seen on Dr. Gougaloff 's Ridge Expansion Video.

Nerve Repositioning Procedure:

This procedure is also known as Nerve Transopsitioning or Nerve Lateralization.  This procedure is usually indicated when the nerve and vessel canal inside the lower jaw is ‘riding’ very high and prevents Rootform Implants of sufficient length  from being placed without injuring the canal.  This procedure is limited to the lower jaw and indicated when teeth are missing in the area of the two back molars or/and the 2^nd premolar, with the above mentioned secondary condition.  Since this procedure is considered a very aggressive approach (there is almost always some postoperative numbness of the lower lip and jaw area, which dissipates only very slowly if ever), usually other, less aggressive options are considered first (placement of Blade Implants etc.).

Below you see in a model what a Nerve Repositioning entails:

In this procedure we typically remove a cortical (outer) section of the cheek side of the lower jawbone (as shown above) in order to expose the nerve and vessel canal.  Then we isolate the nerve and vessel bundle (neuro-vascular bundle) in that area, and pull it out to the side a little.  At precisely the same time we place the implants while we keep traction on the neuro-vascular bundle.  Then the bundle is released and placed over the implants.  The surgical access is re-filled with bone graft material of the surgeon’s choice  and the area is closed.

Click on the "Show Procedure" button below to see images of a typical Nerve Repositioning procedure.

A video of a nerve repositioning procedure can be seen on Dr. Gougaloff 's Nerve Repositioning Video.

In-Situ Grafting Procedures:

This category encompasses all other grafting procedures.  For instance, an implant is immediately placed into the socket of an extracted tooth.  Most of the time there will be a discrepancy between the implant diameter and the diameter of the socket, which translates into a gap between the wall of the implant and the bony wall of the socket as you can see in the picture in the FAQ section How Many Implants Do I Need?.  These gaps are usually filled with bone grafting material (and sometimes covered with a membrane) to prevent soft tissue from growing into this space.

Another In-Situ Grafting procedure would be if an implant were placed into the bone with an exposure of threads on one of its sides.  Most of the time these exposures are grafted and covered with a membrane.  While the implant integrates in the bone the membrane will allow bone to re-model and re-grow underneath it without letting any cells from the soft tissues disturb and possibly hinder the process.

Click on the "Show Procedure" button below to see an example of this.

Finally when implants undergo bone loss over time, either due to the lack of plaque control or, more importantly, mechanical overload (a condition we refer to as Peri-Implantitis) we can sometimes use bone regeneration and grafting techniques similar to the ones used in modern Periodontics to restore some of the lost bone on certain implants.

For more information, please visit also Dr. Gougaloff's website and Dr. Gougaloff's blog on implant dentistry.