Bone augmentation
Frequently the height or width of the jawbone is reduced by bone loss (atrophy), leaving insufficient existing bone mass to support an implant. If implants are required the bone needs to be built up. This procedure, known as bone augmentation, can be done before or at the same time as the implant placement. Either the bone from the patient’s body or a bone substitute can be used.
The best material for bone grafting is still bone from the patient’s own body (autogenous bone), from the lower jaw or the chin, for example. Only in cases of extreme bone atrophy is it necessary to take the bone graft from an extraoral site such as the hip.
Vorteil des Eigenknochens ist die gute und schnelle Einheilung. Knochen enthält Wachstumsfaktoren, die eine schnelle Inkorporation des aufgebauten Materials bewirken.
Nachteil bei der Verwendung eigenen Knochens ist die notwendige Entnahmeoperation, die manchmal zu Komplikationen führen kann.
The harvested bone is used in the form of blocks which are fixed with small titanium screws to the part of the jaw requiring augmentation; alternatively the bone may be ground and used in the form of granules which are covered with a special membrane (e.g. Bio-Gide®). After about 6 months the bone graft is integrated and the implants can be placed.
Bone augmentation using membranes is also called GBR (guided bone regeneration) or GTR (guided tissue regeneration). Bio-Gide®, for example, is a collagen membrane which dissolves and therefore does not have to be removed.
Bone substitutes (e.g. Bio-Oss®) of synthetic or natural origin can also be used for smaller defects. “Artificial bone” is infiltrated and gradually replaced by bone from the patient’s own body in the course of 3-8 months. Advantage: The use of bone substitutes means that no bone has to be harvested from the patient’s body. Artificial bone and autograft bone from the patient’s own body can also be mixed.
Bone substitute materials and membranes: artificial bone (here Bio-Oss®) is available in the form of granules of different sizes or as block.
Guided bone regeneration (GBR):
Left: Bone substitute material (Bio-Oss®) is covered with a collagen membrane (Bio-Gide®).
Middle: After about 8 weeks blood vessels and bone-forming cells have grown into the artificial bone
Right: After several months the membrane has dissolved, the foreign material has been completely replaced by newly formed bone from the patient’s own body.
Deficient alveolar ridge: Before implant placement the bone is augmented with a block graft (1). Smaller bony defects are filled with bone granules or bone substitute during the implant procedure (2-4).