Bone grafting is a surgical procedure where the clinician replaces your missing or inadequate bone volume with biomaterials of different sources. The procedure involves placing these materials in contact with bone to augment its dimensions. This allows for successful implant osteointegration in the future.
Some instances when grafting is necessary :
- Following tooth extraction, in order to maintain the dimensions of the alveolar socket.
- For "sinus augmentation" procedures. Sinus augmentation procedures are performed in cases that require additional bone in the vertical direction in the posterior region of the upper jaw. The placement of an implant without sufficient bone in this area would cause the top portion of the implant to come in contact with the interior of the sinus causing irritation and inflammation. The area with insufficient bone is replaced with graft material.
- For "lateral ridge augmentation" procedures. Cases with insufficient bone surrounding the implant site require the use of graft material placed in all horizontal directions so that 2 mm of future bone is obtained prior to implant placement.
Following tooth extraction a clot forms inside the tooth socket. In time, this clot remodels leaving behind bone. During the remodeling process the clot shrinks and the resulting bone height and width will decrease. Replacing missing teeth with implants is the most common procedure. Successful implant osteointegration and esthetic outcome are dependent on bone availability prior to implant placement. Bone grafting procedures aim to restore the alveolar bone to suitable dimensions in order to support a future implant.
An autograft involves bone collected from other parts of the patient's body. This type of graft has the possibility to induce bone formation with no host response from the patient's body. The main disadvantage with an autograft is that it requires a second surgical site that can lead to additional pain, infection and bone related complications.
Allograft bone is bone collected from another patient or cadaver. It eliminates the need for a second surgery; however, there is a chance of disease transmission from the donor. Since allografts lack protein components due to sterilization, the healing time is increased. The most common allograft in use is Demineralized Bone Matrix (DBM). Many studies have reported contradictory reports on its efficacy. The quality of the donor bone can cause variability in the material. Xenografts are graft materials obtained from animal bone.
Synthetic alloplast materials have been developed to confront the issues brought on by the other types of grafts. Alternative materials can be ceramic-based (calcium phosphates, calcium carbonates, calcium sulfates), natural or synthetic polymers. Growth factors can be added to these materials in order to mimic the properties of autografts. Calcium sulfate-based materials are inexpensive, biocompatible and resorb completely leaving behind native bone. Calcium sulfate stimulates the formation of blood vessels, which provide nutrition for growing bone. Calcium sulfate can be used alone or in combination with other graft materials, drugs or growth factors.
Bone regeneration refers to instances when a material used to fill a bone defect resorbs completely and stimulates new bone formation.
Bone replacement refers to cases where a bone defect is filled with a material that does not resorb, filling the space without stimulating new bone growth.
It is important to have direct contact between host bone and the implant, as implants placed in native bone have higher rates of osteointegration and success. It has been shown that the higher the bone-to-implant contact, the higher the success rate.