Bone Grafting

Today, we have the ability to replace or regenerate bone where needed. This gives us the opportunity to place implants of proper length and width in areas that would otherwise not be suitable for implants. 

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, due to a lack of available bone, patients are not candidates for the routine placement of dental implants.

Bone grafting can repair implant sites with inadequate bone structure due to previous extractions, extensive periodontal disease or traumatic injuries. The bone is either obtained from a tissue bank or your own bone is taken from other places in the jaw.  Occasionally, repair of major defects requires bone to be harvested from the hip or other sites outside the jaws.   These procedures are usually needed for bone defects from trauma or pathology, and require inpatient hospitalization.  The great majority of bone graft procedures for implants however are usually performed as office procedures.

Particulate Bone Grafting

For areas that require fairly minimal replacement of bone, we can often use bone grafts that consist of small bone particles that cane be used to widen a thinned extraction site.  This is often done as a separate procedure, but is commonly done at the same time as implant placement.  The bone is either bovine (cow) bone, or bone from human sources.  All bone graft materials are obtained from companies that strictly adhere to the requirements of the American Association of Tissue Banking, and are extraordinarily safe for use in all patients.

You may hear the term Guided Tissue Regeneration used with respect to bone grafting.  This refers to the placement of a membrane over the grafted material before the soft tissue flap is replaced over the site.  If the soft tissue flap is simply placed over the site after a graft has been placed, it becomes a race between the soft tissue cells growing into the graft from the outside (which we don't want), and the bone cells growing through the graft on the inside surface of the graft (which we do want).  The placement of the membrane over the graft prevents the soft tissue cells from growing through the graft, and allows the new bone cells only to grow through the grafted particles, thus producing a more successful graft.   These membranes are either resorbable (will melt away on their own) or ones that may have to be removed later on.

Socket Grafting

When a tooth is removed, the remaining tooth socket "shrinks" in width and height during the healing process, often leaving an unacceptable bone contour for implants or even for traditional bridgework. In many cases, especially in the teeth in the front of the mouth (where esthetics are a greater concern), placement of a bone substitute material will often maintain the dimensions of the bone, as the patient's own natural bone slowly replaces the graft material over time. This also helps maintain the proper soft tissue contours, so that the gum tissue will look more natural when the implant is restored or the bridge is placed.

Onlay Bone Grafting

Sometimes the amount of bone needed may be too large for the use of particulate bone.  In these cases, bone can often be obtained from another area in the jaw and grafted to the site where it is needed. The chin or the area in the back of the jaw behind the teeth are common areas where bone can be obtained. 

Sinus Lift Procedure

Occasionally, following the removal of the upper back teeth, the sinuses will enlarge over time, reducing the amount of available bone for implant placement. When implants are desired in these locations, there is often not enough available bone to accommodate the implant fixtures. This problem can often be overcome by a surgical procedure (known as a Sinus Lift) where the sinus membrane is lifted up, and graft material placed in order to increase the amount of bone for implant placement. Sometimes the implants can be placed at the same time as the sinus graft if there is still enough natural bone to partially stabilize the implants after placement.  In other circumstances, it is necessary to perform the graft first, and then place the implants later when the graft has healed.

Bone Morphogenetic Protein (rBMP)

Bone Morphogenetic Protein technology is a medical breakthrough that allows us to grow bone in an area with only small amounts of particulate graft material.  The BMP bone graft also grows bone faster than traditional particulate grafts.  In traditional particulate grafts, the body's own bone cells have to grow around the grafted bone particles.  It has to then resorb all the grafted bone scaffolding, and then replace it with your own natural bone.  This often meant waiting from 6 - 12 months for the graft to "take" before implants could be placed in the site.  This was especially true for sinus lift procedures, where the implant is often supported almost entirely by the grafted bone alone.  In the past, it was often necessary to wait the full 12 months before being able to place the implant fixtures.  With BMP technology, this time has been reduced to approximately 4 months, and the quality of bone is usually better.  

The BMP product that is being used presently is known as INFUSE, and is manufactured by Medtronics.  It comes in a liquid form that is transferred to a collagen sponge,  This sponge is then mixed with a small amount of particulate bone to give it consistency, and is then grafted to the recipient site.   As this product is manufactured using recombinant DNA technology to produce the BMP (which is usually referred to as rBMP, with the "r" standing for 'recombinant"), it is quite expensive, when compared to traditional graft materials.  Given the outstanding bone that is produced, the reduction of treatment time, the predictability of the results, and the ability to often avoid more invasive procedures to harvest bone, the use of the rBMP material is often a wise choice, especially when it comes to sinus lift grafting procedures.

The sinus graft makes it possible for many patients to have dental implants when years ago there was no other option other than wearing dentures.

Ridge Expansion

In severe cases, the ridge has been reabsorbed and a bone graft is placed to increase ridge height and/or width. This is a technique used to restore the lost bone dimension when the jaw ridge gets too thin to place conventional implants. In this procedure, the bony ridge of the jaw is literally expanded by mechanical means. Bone graft material can be placed and matured for a few months before placing the implant.