Patients wishing to have a dental implant may sometimes be recommended to have a bone graft beforehand. This is likely to be because they don’t have sufficient bone in their jaw to support the implant, or that the existing bone simply isn’t strong enough. Most standard sized implants require 3mm of healthy bone to surround them. It might sound like a large procedure, but in fact it is very straightforward and is far more common than you might imagine. You may also hear bone grafts being described as bone augmentation.
Deciding if You Need a Bone Graft
Part of the initial consultation for a dental implant will involve x-rays and CT scans, and these will show your oral surgeon whether or not your bone has the right mass and density to support an implant. If it doesn’t then the next step will be to plan for a bone graft. There are several different types of grafts, so you’ll be able to discuss these options with your surgeon before deciding on the most suitable option.
Different Types of Bone Grafts
Autograft – this is where bone is harvested from another site on your body such as your hip of elsewhere in your mouth. It is considered to be one of the most successful techniques as the bone will be fully compatible and there is little risk of rejection. The harvested area will quickly regrow new bone, but the actual harvesting site can be quite sore for a while afterwards. The technique is also quite specialized, and isn’t offered by all dentists, and it does mean undergoing two different surgical operations.
Xenograft -this graft uses bone harvested from animals and is usually bovine. The harvested bone is processed and thoroughly sterilized to make sure it is safe for use. Animal bone is pretty compatible with human bone, and will eventually be replaced with the patient’s own bone. One advantage of this process is that only one small operation is required, but some people find using animal bone off putting.
Allografts -these grafts are from human donors, and the bone is harvested after death. It is rigorously tested and treated to ensure it is as free from disease as it possibly can be, and it’s sterilized before being used. Once it is placed in the jaw it will eventually be replaced with the patient’s own bone. While this type of graft is preferable as it only involves one operation, there is always a tiny risk of disease transfer, or of an immunogenic reaction. In addition this type of graft can be relatively slow to fully integrate with existing bone. The actual process for harvesting bone can weaken it substantially, and many people do not like the idea of using bone form a cadaver.
Alloplastic grafts – these are made from synthetic materials and often contain calcium phosphate found naturally in bones. These grafts are gradually reabsorbed into the body, and are replaced with the patient’s own bone as they encourage natural bone growth. However some alloplastic grafts are made of a material which isn’t reabsorbed by the body, as it is designed to act as a framework to encourage the growth of new bone. This type of graft has several advantages as there is zero risk of disease transfer, and the grafts can be modified to give a perfect fit in the jaw. They only require one surgical procedure and are made of materials that are often biodegradable. In spite of this there is the slight risk the graft will be rejected by the body.
The Procedure for Placing a Bone Graft
The actual process for placing an implant is very simple, and involves the surgeon cutting into the gum to expose the bone. The graft is then placed and covered with a protective membrane which will aid the healing process and help prevent any infections, although sometimes the graft may be held in place with small screws. The final step is to replace the gum tissue and to stitch it back into place. You’ll be given precise instructions on how to care for the graft site, and may also be prescribed antibiotics and antibiotic mouthwashes.
The healing times can vary from person to person, but it generally takes around four months for the graft to fully take. Your dentist will be able to see how the graft is doing by taking x-rays of the site. This will show them the new height and width of the bone.
Sometimes a dentist may choose to place the implant at the same time as the graft, but this does very much depend on the implant system being used. These are all things the dentist will discuss with you. The costs of bone grafts can vary, but most dentists will build the price into the cost of the dental implant. You should be able to see exactly how much each stage will cost from your treatment plan.
Success Rates of Bone Grafts
Bone grafts generally have a very high success rate, but as with any surgical procedure there are always risks. Bone grafts can occasionally fail, even if the bone was harvested from another site in your body. Certain people, such as smokers or those with certain medical conditions are more at risk of having a bone graft fail. However a failed bone graft can often be re-done at a later date, once the area has had a chance to heal.