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.
The areas marked in red indicate the possible bone harvesting sites in the mouth. chin, mandibular angle, ascending ramus of the lower jaw and maxillary tuberosity in the posterior upper jaw.
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 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..
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.
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).
Sinuslift (Sinus floor augmentation)
A special kind of bone augmentation is the sinus lift. In the region of the back teeth of the upper jaw the large air-filled maxillary sinus often leaves insufficient bone mass for successful implant placement. Here the bone augmentation procedure known as sinus lift can help. Through an operative access from the mouth, the floor of the maxillary sinus is exposed and the membrane lining the sinus is carefully raised. The resulting space is filled with bone substitute material. In the case of sufficient height of the alveolar bone, the implants can be immediately placed. If the bone thickness is insufficient for stable anchorage of the implant, the bone is first built up and implants are placed into the reconstructed bone after six months.
The video simulation (1 MB) shows how the sinus lift procedure is performed.
Sinus lift with simultaneous implant placement. The inserted bone substitute is gradually replaced by natural bone within about 6-9 months.
Scientific studies have shown without any doubt that in the case of maxillary sinus floor elevation (sinus lift) the results obtained with artificial bone are just as good as those obtained with autograft bone. For this reason we use only bone substitutes such as Bio-Oss® for the sinus lift procedure and thus spare our patients the harvesting of autogenous bone.
Today, the sinus lift is a routine operation which produces predictably good results in experienced hands. Nevertheless, the exposure and fenestration of the lateral maxillary sinus wall constitute a not inconsiderable operative trauma for the patient. Therefore the current trend is towards the use of minimally invasive surgical techniques for this procedure. In balloon-assisted sinus floor elevation (Balloon Lift Control) a balloon is inserted under the lining of the maxillary sinus through a small access at the site of the planned implantation and carefully filled with fluid. The pressure of the balloon gently raises the membrane lining the sinus while the sinus is viewed through an endoscope. When the desired volume has been achieved the balloon is emptied and removed and bone substitute placed in the resulting space through the same access.
This minimally invasive sinus lift is not particularly stressful for the patient and minimises the risk of an infection after the procedure. We therefore use this procedure in suitable cases.
In spite of all progress, bone augmentation always carries certain risks. For example, the bone graft can be lost through a wound infection. For this reason we try to avoid major bone augmentation wherever possible. New procedures help us to do this: Three-dimensional X-rays and computer guided implantation enable us to make optimal use of the available bone and with innovative methods such as All-On-4 und zygoma-implants we can often do without bone grafting entirely.
The balloon is filled and lifts the lining of the maxillary sinus.
After removal of the emptied balloon a space remains.
The space is filled with artificial bone.
Chapter overview: Implants
- What is an implant?
- Single-tooth implant
- Implants in the toothless jaw
- Bone augmentation
- New surgical procedures
- Immediate implants
- Risks and complications of dental implants
- Costs and guarantee of implant treatment
- Questions and answers about dental implants
Download the entire illustrated text Better Quality of Life with Dental Implants:
Better Quality of Life with Dental Implants (pdf 2 MB, possibly long download time)