This is the process in which the dentist uses bone grafts to build up a thin or shrunken jawbone. If you are considering an implant but dental x-rays and/or CAT scan show that you have a thin jawbone as a result of bone loss then a graft will be necessary.
Your jaw may show advanced bone loss as a result of the ageing process, prolonged denture wear, missing teeth, periodontal gum disease or as a result of an accident.
What causes bone loss?
If you lose a tooth through accident or injury then what tends to happen is that the area around the missing tooth recedes and the jawbone itself starts to shrink.
Our teeth help to maintain bone density by a natural renewal process. This ensures normal bone growth and healthy tooth tissue.
Another factor is that of aesthetics: if a person has lost several teeth and has not replaced them then their facial jaw line will appear lined and ‘sunken in’. This aged appearance is both undesirable and unnecessary.
One way of preventing this is via a dental implant but this may have to be combined with a bone graft.
Bone grafts are a recent innovation and are highly successful. They involve the grafting of bone from one area of your body into your jawbone to increase its width and depth.
Ideally, bone will be grafted from your own body although a synthetic alternative can be used.
There are four types of bone grafts:
- Autogenous or Autografts
This is the most popular and successful of all the grafting techniques and is often referred to as the ‘gold standard’ in bone grafting. It involves the removal or ‘harvesting’ of bone from a designated donor site such as the hip.
The hip is the preferred source as this is rich in marrow which means a ready supply of bone cells.
This bone is then grafted into the jawbone.
This is the most successful of all four techniques as the grafted bone aids with the regeneration of the jawbone.
This is similar to an autogenous graft in that it uses natural bone, although this is taken from a human donor rather than a part of your own body. There are special ‘bone banks’ for this purpose where people have donated bone samples – which are very similar to blood banks.
If you are not keen to have an autogenous bone graft then this is an option. The donor bone is taken from a source of human cadavers via a special ‘bone bank’ and is rigorously checked and sterilised before grafting takes place.
Donated bone is tested and then sterilised before being grafted into your jawbone. Your body then assimilates this donor bone into your natural bone (of your jaw).
This is a third option: The difference between this and the other two procedures is that the donated bone is harvested from animals rather than a human donor.
Bovine (cow) is the preferred form of animal bone for this graft. You may feel uncomfortable about this and worry about the safety aspects but this undergoes a system of rigorous testing beforehand. This is to ensure that it is sterile and compatible with your anatomy and bone composition.
This grafted bone acts as a ‘stand in’ which your body will replace with natural bone over time. This formation of new bone is called ‘Osteoinduction’ which uses a special protein called Bone Morphogenic Protein (BMP) to initiate this response.
This is the fourth technique in the bone grating series. This differs from the other three in that it is a man made graft rather than natural bone.
This graft is a synthetic version, made of calcium phosphate which looks almost identical to natural bone. There are two types of alloplastic grafts:
A resorbable graft means that it will be replaced by natural bone by your body. This doesn’t happen with the resorbable type of graft but it can still be used to form a structure to hold the implants. This formation of a structure or ‘scaffold’ applies in both cases.
If you require several implants then the amount of bone to be grafted will increase in proportion to the number of implants.
This procedure is usually carried out in hospital and requires an overnight stay.
Bone grafting is a very successful procedure although you do need to know that like all procedures there is a tiny risk of rejection. We cannot be 100% certain as to why this happens although we can highlight contributing factors such as smoking and certain medical conditions. These can predispose the patient to this risk.
Bone graft failure can happen as a result of an infection or as a result of the grafted bone becoming loose and refusing to stabilise in the jaw.
If you experience bone graft failure then you will have to undergo removal of the rejected graft followed a period of healing before a second graft can take place.
There are other techniques available which can help with bone loss such as a sinus lift or elevation, ridge expansion and distraction osteogenesis.
Bone grafting procedure
This depends on the type of graft technique. If you are having the autogenous graft then the procedure involves the dentist making a small incision in the donor site (designated part of your body) to remove a small section of bone. This is usually the chin or the hip.
This is the first part of the process.
The second part involves the making a tiny incision in your gum to expose the jawbone. The dentist can then graft the harvested bone onto this area.
The main advantage of this type of graft is that there in no risk of rejection as the bone is taken from your own body.
You will experience some discomfort in both the donor area of your body and your jawbone although painkillers will control this.
A bone graft can be carried out using a local anaesthetic and sedation (if required).
Are there any disadvantages?
No procedure is 100% successful and this includes bone grafts. The autogenous graft is seen as the best technique but fusion is not completely guaranteed.
You may have to wait from 3 months to a year before your jaw is ready to take dental implants. If you have had a large amount of bone grafted then this will take longer than a small amount.
This seems like a long time but you do need to be patient and wait until your jaw has healed before having the implants.
Platelet Rich Fibrin
Platelet Rich Fibrin or PRF is a type of ‘glue’, used in dental surgery, which helps to speed up the healing process. It is a key element in this process which stimulates new bone and tissue growth.
It is seen as an important factor in wound healing as part of the implant treatment process.
What is a sinus lift/graft? This is a very similar procedure to bone grafting in that donor bone is used to build up an area of the jawbone which is considered to thin for implants.
In this case, the upper jawbone is the area to be treated. The upper jaw is usually thinner than the lower which makes it more difficult to insert dental implants.
Why? Just above your upper teeth are your ‘maxillary sinuses’ which are basically ‘air spaces’ in your jaw. And, very often there is only a thin wall of bone separating the sinuses from your teeth.
Think of the sinus wall (or rear maxilla) as the ‘roof’ of your upper jaw. If this sinus wall is too thin then it is impossible to insert a dental implant as there is no solid foundation to hold it in place. The maxillary jaw (upper) will need to be built up via a bone graft in order to retain an implant.
Previously, if you had advanced bone loss then your only option was dentures but thanks to new grafting techniques, implants are now an option. The dentist can bulk out the sinus wall by lifting the sinus membrane and then grafting donor bone onto the sinus wall.
This will increase the depth and width of the sinus wall in preparation for the implants. The sinus wall will be given time to heal (osseointegration) before a second procedure – insertion of the implants.
This graft can be performed as an autogenous graft.
This is the technical term for a type of bone graft which takes place outside of the jaw. It is used to treat ridged or bony areas of the jaw which have started to shrink or ‘resorb’.
If a jaw has started to shrink then it will require bone grafting to increase its volume before considering dental implants. This means taking donor bone from a part of your body, such as your hip, and then grafting that onto your jaw to bulk out that area.
This new bone is placed directly on top of the jaw.
You will be advised to wait for a few months before having implants to allow the area to heal. In this time new bone will have formed which will strengthen the jaw and enable it to hold an implant securely in place.
If your jawbone lacks enough width to hold implants then a ridge expansion an option. This means splitting the jaw along the top (or ridge) before grafting bone into this era. Once this has healed then implants can be inserted.
The implants can be inserted straightaway although many dentists prefer to wait for a few months until the ridge has healed before implant insertion.
A new and innovative technique which was initially developed to lengthen the bones of the legs in patients who are abnormally short of stature. This successful technique has now been applied to the dentistry field.
It involves making a series of incisions in the patient’s jawbone in order to divide a section of bone from the rest of the jaw. A titanium device is used with screws or pins to keep this section apart from the rest of the jaw.
This space is widened over time by unscrewing this device, which also causes the space between the pieces to fill with new bone. The separation of the bone is the ‘distraction’ part and the formation of new bone is called ‘osteogenesis’.
It tends to be used in patients who require a ‘taller’ jawbone although it is can be used to increase bone height in other directions.
This is the name given to the procedure in which the dentist moves a nerve in the lower jaw – called the inferior alveolar nerve, to one side. This enables him/her to insert a dental implant.
Why might this be needed?
This nerve runs through the lower jawbone and is responsible for sensation in the chin and lower lip. If someone has lost a fair amount of bone from their jawbone then this nerve is likely to be too near the surface. This means an implant cannot be inserted without damaging this nerve. Any damage to this would cause a loss of feeling in the lower lip or chin.
One answer to this is for the dentist to drill a small hole in the jawbone before moving the nerve to one side. He or she can then insert a dental implant.
However, this technique is not performed that often because there is a risk of damaging the nerve by moving it. If your dentist mentions about nerve repositioning then rest assured that he or she will consider it carefully.
There is another addition to the bone grafting family called ‘Barrier Membranes’. These are used to help with the formation of new bone.
When bone loss occurs a ‘competition’ begins between three groups of cells - connective tissue cells, epithelial cells and existing bone cells. They fight amongst themselves to fill in the area where there is bone loss.
The bone cells are usually the losers but a barrier membrane can block the connective and epithelial tissue cells which allow the bone cells to ‘win’ and so regenerate themselves.
What is a barrier membrane made of?
There are two types of barrier membrane: resorbable and non-resorbable. The first barrier membranes were the non-resorbable sort and were used for some time before the development of the resorbable type.
Whichever is used the main issue here is that of stability. The membrane and the graft need to be fixed firmly in place. If they move or shift around then there is the danger of incomplete healing and bone regeneration. The end result is a soft, osteoid like tissue which is unable to stimulate the growth of new bone cells or build up the jawbone.
Special ‘tacks’ are used which are very similar to the ones used in conventional DIY. They are pushed into the bone to help secure the graft and the membrane.
If the membrane is the non-resorbable type then this will be removed along with these tacks.