Monday, November 2, 2009
Bone Grafts : Reverse Jaw Bone Loss
Bone grafting is a surgical procedure that replaces missing bone with material from the patient's own body, an artificial, synthetic, or natural substitute. Bone grafting is possible because bone tissue, unlike most other tissues, has the ability to regenerate completely if provided the space into which to grow. As native bone grows, it will generally replace the graft material completely, resulting in a fully integrated region of new bone. The biologic mechanisms that provide a rationale for bone grafting are osteoconduction, osteoinduction and osteogenesis.The most common use of bone grafting is in the application of dental implants, in order to restore the edentulous area of a missing tooth. Dental implants require bones underneath them for support and to have the implant integrate properly into the mouth. People who have been edentulous (without teeth) for a prolonged period may not have enough bone left in the necessary locations. In this case, bone can be taken from the chin or from the pilot holes for the implants or even from the iliac crest of the pelvis and inserted into the mouth underneath the new implant.In general, bone grafts are either used en block (such as from the chin or the ascending ramus area of the lower jaw) or particulated, in order to be able to adapt it better to a defect.Another common bone graft, which is more substantial than those used for dental implants, is of the fibular shaft.
When bone graft is implanted in the jaw, it doesn't just simply fill a void in the bone; it may also help promote new bone growth in that location. When successful, bone grafting can restore both the height and width of your jaw bone.There are several bone graft options, and they differ in how they help promote bone formation. They include:
* Autogenous Bone Grafts. Also called autografts, these types of grafts are made from the patient's own bone, harvested from elsewhere in the body. Typical harvest sites include the chin, jaw, bone of the lower leg (tibia), hip (iliac crest) or the skull (cranium).Autogenous bone graft has traditionally been considered the "gold standard" as a graft material because it is "live bone" complete with the living cellular elements that enhance bone growth.
* Allogeneic Bone. Allogeneic bone, also called allograft, is bone derived from a genetically unrelated member of the same species. It's typically non-vital (dead) bone harvested from a cadaver, then processed using a freeze-drying method that extracts all the water via a vacuum.
* Xenogenic Bone. Similar to allogeneic bone, xenogenic bone is non-vital bone derived from another species, usually a cow. Because the potential for immune rejection and contamination by viral proteins is higher in bovine bone than in human cadaver bone, xenograft material is processed at very high temperatures (600-1,000 degrees Celsius). Xenograft's mechanism of action is similar to that of allograft – it serves as an osteoconductive framework on which bone from the surrounding area can grow to fill the void.
Bone graft substitutes are commercially produced synthetic products that have many of the same bone forming properties as human bone, and are a safe and proven alternative to autograft and allograft.One of the advantages of using a bone graft substitute instead of autogenous bone is that it eliminates the need to harvest the patient's own bone, thus potentially reducing the risk and pain associated with the harvest procedure.
Some bone graft alternatives include:Demineralized Bone Matrix (DBM)/ Demineralized Freeze-Dried Bone Allograft (DFDBA),Bone Morphogenetic Proteins,Ceramics and Graft Composites.