Types of Dental Bone Grafts
Bone graft materials are classified based on the source of the bone used in the procedure as:
Autografts - Autogenous Bone Grafting
The most popular areas for bone harvesting are the chin or the ramus (the vertical back part of the lower jawbone close to the temporomandibular joint). If bigger quantities of dental implant bone graft are needed, the bone graft can be taken from other body areas, usually the hip bone. The hip is considered to be a good quality source because the hip bone has a lot of marrow, which contains bone-forming cells.
When the dental implant bone graft is taken from the chin the procedure can be performed by the dentist in the dental office under local anaesthesia. If the bone graft has to be collected from the hip or other body part, the procedure has to be performed in a hospital by an orthopedic surgeon.
Allografts - Allogenous bone grafts
Allografts are human bone grafts taken from another person and usually provided by bone banks. This type of dental implant bone grafts provide an alternative for patients who want to avoid the surgical procedure required for taking the autografts, or when very large blocks of bone are needed. However the patient must consider the additional cost for obtaining them from a bone bank.
Allografts have lower performance than autografts in bone regeneration, therefore it is expected that the treatment time will be longer. Autografts have generally less failure rate than allografts. Disease transmission risks are diminished by tight screening protocol and advanced processing technologies followed by bone banks.
The main advantages of allogenous bone grafts are that they are available in unlimited quantities and they do not require a second surgical procedure to harvest them.
Xenografts are bone grafts from other species, usually from bovine (cow) or porcine (pig) origin. The molecular structure of bone is the same across species, making possible to use bone from animal sources for dental implant bone grafts with very good results.
Xenografts contain only the sterilized non organic materials of the animal bone. They are used as a scaffold from the body which tears down the bone graft and replaces it with natural bone.
Alloplasts make use of synthetic materials for bone formation. Dental implant bone grafts made of synthetic material (calcium phosphates or hydroxy apatite) work by stimulating the body to form natural bone at the site of dental implant. These materials can be used in conjunction with growth factors or mixed with bone marrow to increase biological activity. Alloplastic bone grafting is believed to be less effective than autogenous bone grafting but it has much less risk for infections.
Other materials used in bone grafting procedures include:
Growth Factor Enhanced Grafts are produced using recombinant DNA technology, therefore they are more expensive than other types of dental implant bone grafts. They consist of human growth factors such as Platelet Derived Growth Factors or Bone Morphogenic Proteins, in conjunction with a carrier medium, such as collagen. Growth factor enhanced grafts can considerably accelerate the bone formation process.
Barrier membranes are very often used to guide the bone regeneration, with or without the use of bone grafts. After applying the dental implant bone graft material, a membrane made of biocompatible material is placed between the gum and bone in order to stabilize and 'protect' the bone graft. Gum tissue grows much faster than bone tissue. Without using a membrane to isolate the bone graft, the gum tissue would invade and fill the area not allowing bone growth. Barrier membranes are a very useful tool in promoting the growth of new bone in a 'Guided Bone Regeneration' process.
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