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Complex Bone Grafting Cases

If you do not have enough bone what can be done?

So far we have covered the building blocks that are part of routine implant placement. This has included the initial examination and diagnosis, special x-rays such as CBCT scans, sedation during surgery and what to expect after the implants have been placed. However, for some people, bone loss after the removal or loss of teeth leaves them without enough to secure an implant. There are procedures that can be done if this is the case:

In the upper jaw above the back teeth, it is possible to increase the height of bone available by creating new bone in the sinus. This procedure is called a ‘sinus augmentation’. A skilled surgeon can deliver highly predictable results in this location and without the general success of this technique many patients would be unable to have implants in a part of the mouth where teeth are so commonly missing.

There are many ways in which bone can be added; however, one simple concept is to take a piece of bone from somewhere else and secure it as an ‘onlay graft’ to a deficient area. The new piece of bone will slowly join to the underlying region and when healed and mature, an implant can be placed in a more favourable position.

Where can you get extra bone from?
Bone can be harvested from a number of sources but usually from behind the back teeth in the lower jaw or from the chin. Sometimes it is taken from the hip or shinbone (tibia). When you use your own bone to create new bone in another area of the mouth you will have to contend with the discomfort created by the donor site as well as the surgical site. Many people feel this is well worth any additional discomfort as your own bone is normally considered the ‘gold standard’.

Alternatives to your own bone for grafting
For those who would prefer an easier but slightly slower, solution there are other sources of bone such as bovine (derived from cow), porcine (derived from pig) or synthetic materials that have been specially prepared to make them safe for use in humans. All of these materials, including your own bone, simply provide a scaffold into which new bone will grow in order to be ready to receive dental implants a few months later.

New bone can take anything from 3 to 12 months before it is ready to receive dental implants. Do not be in a hurry to move to the next stage. If you need a large volume of bone it will take longer to mature than a small amount.

Each surgeon will have his or her preferred way of creating new bone. Many of them will also use a supplementary technique called ’guided tissue regeneration’. Using this technique, slow-moving bone cells are given time to fill a space by placing a barrier material between them and the fast moving cells of the soft tissues lining the mouth. This is a ‘resorbable barrier’ that will disappear naturally a few months after it has done its work.

Does bone grafting affect the length of treatment?
If you need bone grafting, it will almost invariably increase the length of time your treatment will take; however, when successfully applied it will greatly improve the outcome of the implant(s) placed. When used in the front of the mouth it can also allow for creation of much better aesthetics.

Bone grafting requires a considerably higher degree of skill from the operator and is often more complex to perform than the placement of the implant itself.

In certain situations some operators will recommend combining the implant placement with bone grafting and the placement of a barrier membrane all at the same time. This considerably reduces treatment time and can produce results that are difficult to achieve any other way. However, many surgeons will still prefer to carry out bone grafting as a distinct stage, so that the implants are only placed when the bone grafting has been successful.

Whatever method is chosen to improve the bone quantity the time, effort and expense is generally well worthwhile.

Block Bone Grafting

By Dr Iyad Abou-Rabii

There are 2 main types:

1. Autogenous Bone Grafts
2. Allograft Bone Block

In the event that a patient doesn’t have the adequate amount of bone structure for dental implants after they have lost a tooth, a dental surgeon may have to harvest the patient’s native bone to increase the bone volume in these areas.

There could be several reasons why a patient would not have the sufficient amount of bone structure to handle an implant and thus would require for a certain procedure like the block bone graft in order to successfully receive dental implants. These reasons would include the following possibilities:

There could be a situation where a tooth was extracted without a socket graft placed in immediately for a new implant or a re-implantation of a tooth.

There could be a situation where a patient would have a missing tooth in which they suffered a lot of bone destruction from a tumour, infection, or cysts.

There could be a situation where a patient’s jaw bone area was congenitally missing which would result in damage to the normal bone structure that would be in place to support the tooth which never fully developed.
Dental trauma can cause a patient to have significant bone loss. In these and many other situations in which a patient doesn’t have enough bone structure to have implants set in place, Dr. Iyad will use a grafting procedure such as the autogenous block bone graft to give you the right amount of bone to successfully sustain a dental implant. This bone grafting would probably come from the lower jawbone in the region where the patient’s wisdom teeth would be located known as the mandibular ramus region. Alternative places could include the patient’s chin.

For a successful procedure, the dentist would remove a small block of bone (usually less than 1 cm square) from one of the two mentioned spots listed above and transfer it to the area where you would have significant bone insufficiency. It will be secured using two extremely small screws and overlaid with a collagen membrane and bovine bone.

Autogenous Bone Grafts

Autogenous bone grafts , also known as autografts, are made from your own bone, taken from somewhere else in the body. The bone is typically harvested from the chin, jaw, lower leg bone, hip, or the skull. Autogenous bone grafts are advantageous in that the graft material is live bone, meaning it contains living cellular elements that enhance bone growth.

However, one downside to the autograft is that it requires a second procedure to harvest bone from elsewhere in the body. Depending on your condition, a second procedure may not be in your best interest.

The Allograft Bone Block

This is bone from a Human Donor.

Provides a predictable and highly effective alternative to traditional block grafting, It is delivered sterile, is readily available, and offers a virtually unlimited source for the surgeon’s block grafting needs.

Increases bone volume for surgical ridge augmentation in patients where bone volume has been reduced due to atrophy, thereby increasing the primary stability of subsequently inserted implants. Solves the problem of the limited amount of bone that can be taken from a donor site.

The allograft bone block replaces the need for autogenous bone harvesting by providing a sterile-packaged block of cortico cancellous bone for implantation. The block allograft eliminates the need for a secondary surgical procedure, thereby saving operating room time and costs, reducing pain and morbidity, and shortening the rehabilitation time for the patient.