grafting & augmentation
Dental implants require bones underneath them for support and proper integration into the mouth. As mentioned earlier bone grafts come in various forms such as autologous (from the same person), Allograft, Xenograft (mainly bovine bone), and Alloplastic materials. Bone grafts can be used prior to implant placement or simultaneously. 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, 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.
Dental bone grafting is a specialized oral surgical procedure that has been developed to reestablish lost jawbone. This loss can be a result of dental infection of abscess, periodontal disease, or trauma. There are various reasons for replacing lost bone tissue and encouraging natural bone growth, and each technique tackles jawbone defects differently. Reasons that bone grafting might be needed include sinus augmentation, socket preservation, ridge augmentation, or regeneration.
various bone grafts
Also termed sinus lift, sinus graft, sinus augmentation or sinus procedure, is a surgical procedure intended to increase the amount of bone in the posterior maxilla (upper jaw bone), in the area of the premolar and molar teeth, by lifting the sinus membrane and placing a bone graft. This increases the volume of bone ofr future placement of the implant fixtures.
A procedure to reduce bone loss after tooth extraction to preserve the shape of the tooth socket in the alveolar bone. After extraction, the jaw bone has to be preserved to keep the socket in its original shape. Without socket preservation, the bone quickly resorbs resulting in 30–60% loss in bone volume in the six months after dental extraction. The jaw bone will never revert to its original shape once bone is lost and tissue contour has changed.
A common dental procedure often performed on an edentulous ridge to help recreate the natural contour of the gums and jaw that may have been lost due to bone loss as a result of a tooth extraction, or for another reason. This procedure is indicated when there is a bone defect in a horizontal and/or vertical direction, with horizontal being more predictable amongst the two.
A type of ridge augmentation that is reserved for larger defects. When the bone thickness or height of bone is severely deficient the block graft procedure can regenerate a larger volume of bone when its is successful. Block grafts have a higher unpredictability rate compared to more mild to moderate ridge augmentation procedures, because of the sheer volume of bone augmented at one time.
Autologous Graft (autogenous, autogeneic, autogenic, autograft or autotransplant)
Bone grafting utilizing bone obtained from the same individual receiving the graft. Bone is harvested from areas such as; the iliac crest, the mandibular symphysis (chin area) or anterior mandibular ramus (the coronoid process). Proximity of the donor and recipient sites reduce operative time and cost. Convenient surgical access, low morbidity, elimination of hospital stay, minimal donor site discomfort and avoidance of cutaneous scars are the added advantages, making intraoral donor sites preferred over the iliac crest of the hip. The disadvantage of autologous grafts is the additional surgical site required, in effect adding another potential location for post-operative pain and complications.
Bone material harvested from one individual and transplanted to another of the same species but not genetically identical. Typically this bone is harvested from cadaver tissue that has been processed and purified, now acting as a scaffold for wound healing. Allografts come in various forms most commonly a particulate form, other manufacturers have processed the bone into a putty matrix. Once the particulate material is layed down it will be covered with a collagen matrix membrane. The membrane acts as a barrier that prevents the soft tissues from growning into the bone graft material disrupting the proper healing of bone.
Xenograft (heterologous transplant or xenotransplants)
Bone material harvested from that of a different species of the recipient. There are multiple sources of bone for xenografts, with the most common being bovine (cow bone) and the others being equine (horse) and porcine (pig). Xenografts are only osteoconductive, meaning they act purely as a scaffold to perpetuate existing bone forming cells from the recipient, making the healing of the graft slower.
Made from hydroxylapatite, a naturally occurring mineral that is also the main mineral component of bone, but can also be made from bioactive glass. Hydroxylapatite is a Synthetic Bone Graft, which is the most used now among other synthetics due to its osteoconduction, hardness and acceptability by bone. Synthetic materials act as great fillers but have various outcomes when it comes to implant dentistry. As a filler the synthetic material will hold and maintain the shape of the residual ridge making it advantageous for the pontic area in bridges.