Dental implants are an elegant and secure way to safely and permanently replace lost teeth. Often, however, the treating dentist already determines at the first examination that there is too little jawbone for a dental implant and that augmentation is necessary. Should artificial bone replacement material fill the defect or is the transfer of the patient's own bone the best way to restore the jaw? The answers to these questions are complex and have to do justice to the individual patient's case.
The insertion of dental implants is comparable to the insertion of a dowel into a wall. If the wall is too thin or the dowel too thick, it breaks out of the wall and what should be held by the dowel falls down. Similarly, dental implants used in a too thin or too weak jawbone can fail to bear the load of the restoration. The implant loses its supporting bone walls under the chewing load and must be removed after a short time. The desired therapeutic success — solid teeth — does not happen.
The lasting success of dental implants is thus highly dependent on the extent of the existing jawbone. As a general rule, a dental implant should be surrounded on all sides by a bone layer of at least 2mm thickness. Often, however, at the time of the decision for a dental implant, this bone volume is not present, because the body reduces the thickness of the jawbone as it is not needed if a tooth is missing.
Materials available for bone augmentation:
To replace lost bone, the following materials can be used:
• The body's own bone
• Natural bone replacement materials
• Synthetic bone replacement materials
The body's own bone can be obtained sufficiently from various parts of the body. In the oral cavity, these include the implant's drill hole, the mandibular (lower jaw) and chin area. Outside the oral cavity, larger amounts of endogenous bone (originating from within the body) can be taken from the anterior pelvic bone (hip). The body's own bone is very well suited for the restoration of jaw defects. There is no risk of infection for the patient and the risk of immunological graft rejection is excluded as it is exclusively endogenous tissue. The body's own bone is therefore superior to all other bone regeneration materials and today remains the gold standard in bone augmentation.
Disadvantages, however, are the limited availability and the need for a further removal point. Usually, either bone particles or whole bone blocks are used. The fixation is done with small titanium or steel screws, which are usually removed after the healing time of the bone graft (about three to four months).
Natural bone replacement materials are derived from animal material (bone and connective tissue) and are available predominantly as granules (ground bone) or as blocks. The most common donor animals are cattle and pigs since the bones of these animals are similar to those of humans. However, preparations of human origin are also available. The products used as medical devices must comply with the requirements of the Federal Institute for Drugs and Medical Devices (BfArM). To eliminate the risk of transmission of infectious diseases such as HIV or hepatitis and immunological rejection, these materials are sterilised and preserved. However, this also alters the biological properties of the materials and may result in increased degradation after surgery. The healing phase after the bone is built up is longer than with the body's own bone (about four to six months).
Natural bone substitute materials are suitable for the filling of smaller jaw defects, or as an admixture to the body's own bone. Synthetic (artificial) bone substitutes consist mainly of calcium-based ceramics or so-called bioactive glasses. They are offered as granules and are due to their lower stability only for use in smaller jaw defects.
As medical devices, they are also subject to:
• the Medical Devices Regulations 2002 (SI 2002 No 618, as amended)
• the General Product Safety Regulations 2005 (SI 2005 No 1803)
• Consumer Rights Act 2015
These are safety regulations under the Consumer Protection Act 1987 and, as such, the Medicines and Healthcare products Regulatory Agency (MHRA) is supervising the use of these products.
Which material is used in the specific case should be determined after the necessary diagnostic measures (clinical and x-ray examination) and the appropriate explanation by the attending dentist. In summary, the body's own bone remains the most predictable method of jawbone construction.