Bone Grafting

The Need:

Over a period of time, the jawbone associated with missing teeth atrophies, or is reabsorbed. This often leaves a condition in which there is poor quality and quantity of bone suitable for placement of dental implants. In these situations, many patients require adjunctive bone grafting prior to or simultaneously with the placement of dental implants.

Today, we have the ability to graft and/or 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 functionality and esthetic appearance.  Bone grafts are typically performed to repair defects of the jaws. These defects may arise as a result of tooth loss, traumatic injuries, tumor surgery, or congenital defects. Large defects are repaired using either the patients own bone or purchasing a product – bone morphogenetic protein (BMP).

When using your own bone, bone is harvested from a number of different sites depending on the size of the defect. The jaw bone, hip (iliac crest), and lateral knee (tibia) are common donor sites. These procedures are routinely performed in our outpatient surgical suite, or occasionally in the hospital, if your health status requires it.

Techniques:

Bone grafting can repair implant sites with inadequate bone structure due to previous extractions, gum disease, or injuries. The ideal bone is your own bone (called “autogenous”), and is usually taken from the jaw, hip, or tibia (below the knee).  Bone can be obtained from a bone bank (allograft), however due to the processing to make it safe, it never becomes vital (alive).  This limits it use to function as a scaffold, basically to allow your own living bone cells to adhere and walk across this banked bone.   

About Bone Grafting

Types of Bone Grafts

Sinus Lift

Sinus Lifts refer to grafting bone in the floor of the maxillary sinus to facilitate implant placement. 

A sinus lift is performed in the molar or premolar area of the upper jaw.   Once teeth have been missing for a period of time, the floor of the maxillary sinus drops down – enlarges.  This resorbs or shortens the bone on the dental ridge where the implant is to to placed.   When the vertical height becomes about 8 mm or less, the sinus lift is performed to allow placement of 16 mm length implants. 

 This is simply done by creating an opening in the side of the upper jaw (maxilla), lifting the membrane that lines the sinus up.  The implants are placed, which provide a tent pole for the sinus membrane.   Bone if then packed in around the implants in this area.  The source of bone is either from the side of the patients lower jaw, or their hip. 

Alternatively to harvesting bone from the patient, via on-site tissue engineering – we can place BMP (Bone Morphogenic Protein) into the site.  BMP will draw in stem cells and grow bone – the patients bone with their DNA. This basically makes for a painfree surgery, and generates the patients own bone.   All types of these grafts are mixed with platelet rich plasma (PRP), and 4 months later the implants are ready to function and be fully loaded with teeth.   When utilizing autogenous bone (your own) or BMP these procedures have a success rate of 98% plus.  

Dr. Loetscher feels that substituting banked bone – either from human cadavers or cows (bovine bone) – has a sigificantly lower success rate – short term and long-term, and typically does not utilize it.  

Bone Grafting Overview

For a brief narrated overview of the bone grafting process, please click the image below. It will launch our educational MiniModule in a separate window that may answer some of your questions about bone grafting.

Bone Grafting Overview

Block Grafts

Often, especially in the front of your mouth – where teeth are missing and have been for some time – the width and height of the bone is inadequate to place an implant in a position that is esthetically appealing and functionally correct.  This leaves too thin a dental ridge to place an implant.   This is corrected by taking a block of bone, usually from the back of the lower jaw (ramus), or the hip (iliac crest) when a large amount is needed.  This block of bone is whittled into shape, and secured using titanium screws.   Since it is your own bone (autogenous), the success with the graft adhering and consolidating is very high.   This process takes 6 months.   After the block graft has consolidated for 6 months, the implants are placed into the bone graft, and restored 4 months later. 

Autogenous Bone Grafts:

Autogenous bone grafts, also known as autografts, are made from your own bone, taken from somewhere else in the body. The bone is typically harvested from the chin, jaw, lower leg bone (tibia), hip, or the skull. Autogenous bone grafts are advantageous in that the graft material is living bone, meaning it contains living cellular elements that enhance bone growth. It is considered the Gold Standard of bone graft materials, because its success rate is unmatched by other materials, and provides living bone adjacent to dental implants.

However, one downside to the autograft is that it requires a second procedure to harvest bone from elsewhere in the body. Depending on your condition, a second procedure may not be in your best interest. Fortunately today, a recombinant DNA product, BMP (bone morphogenic protein) can be used to grow your own bone, with your own DNA. This BMP gives the best of both worlds your own bone, with often no donor site.

Bone Morphogenic Protein (BMP)

In 2007 the FDA has approved the use of a protein called Bone Morphogenic Protein to actually grow bone where there is none. The product has been patented, and is sold by the company Medtronics, under the name Infuse. This is truly a remarkable material.

Basically, through recombinant DNA technology, they have manufactured the exact BMP molecule which exists in our bodies. BMP works by signaling stem cells to migrate to the area, converts them into osteoblasts, which are bone forming cells. These osteoblasts then basically grow bone in the area where the BMP was placed. This often eliminates the need for a donor site such as your hip or jawbone.

The material comes in a liquid form, which we spray onto a sponge type material. This collagen sponge soaked with BMP is then placed where bone is needed, such as in a sinus lift site, an extraction site, or on a deficient dental ridge where implants are to be placed. We also use it as an interpostional bone graft in orthognathic surgery. In 6-8 months, your body literally grows bone into the area, and implants can be placed. What is remarkable about this newly formed bone is the fact that you grow your own bone, with your own DNA makeup, and identical to other bone in your body on a molecular and microscopic level. It is very healthy bone, with a great blood supply, and is ideal to place implants into to support teeth.

Dr. Loestscher has extensive training and experience with the use of BMP.  He has taught courses and lectured on the science and use of BMP. 

Allogenic Bone:

Allogenic bone, or allograft, is dead bone harvested from a cadaver, then processed using a freeze-dry method to extract the water via a vacuum. Unlike autogenous bone, allogenic bone cannot produce new bone on its own. Rather, it serves as a framework or scaffold over which bone from the surrounding bony walls can grow to fill the defect or void.

Xenogenic Bone:

Xenogenic bone is derived from non-living bone of another species, usually a cow (bovine bone). The bone is processed at very high temperatures to avoid the potential for immune rejection and contamination. Like allogenic grafts, xenogenic grafts serve as a framework for bone from the surrounding area to grow and fill the void.

Both allogenic and xenogenic bone grafting are advantageous in that they do not require a second procedure to harvest your own bone, as with autografts. However, because these options lack the transfer of living cells to form bone, bone regeneration is minimal, and may take longer than with autografts, with a less predictable outcome.

Each bone grafting option has its own risks and benefits. Dr. Loetscher will determine which type of bone graft material is right for you.