WHY JAWBONE IS LOST

The bone of the jaw exists to hold teeth. When a tooth is removed, the bone that surrounded its root no longer has a job to do, and the body gradually reabsorbs it.

This happens fastest in the first months after an extraction and then continues slowly for years. The ridge becomes narrower and shorter, which is why someone who lost a tooth a decade ago often has far less bone there than they expect.

Bone can also be lost for other reasons: advanced gum disease, which destroys the bone around the roots of teeth still in place; an injury to the jaw; a cyst or an infection; or long-term wear of a denture pressing on the ridge.

 

WHY A GRAFT MAY BE NEEDED

A dental implant is placed into bone, and it needs enough bone around it in every direction to be stable and to stay healthy long-term. Where there is not enough height or width, a graft adds what is missing.

There are also situations where bone is grafted without an implant in mind — to repair a defect after a cyst or infection has been removed, to rebuild the shape of a ridge that has collapsed under a denture, or to protect the bone around a neighbouring tooth.

 

THE DIFFERENT KINDS OF GRAFT MATERIAL

Four kinds of material are used in dentistry, and they are often combined.

Your own bone (autograft). Taken from elsewhere in your own jaw, most often the back of the lower jaw or the chin. It contains your own living bone cells, which makes it the biological reference standard, but it requires a second site to be operated on.

Human donor bone (allograft). Processed and sterilised bone from a tissue bank, supplied under strict regulation. It acts as a scaffold that your own bone grows into and gradually replaces.

Animal-derived bone (xenograft). Most commonly of bovine origin, processed so that only the mineral structure remains. It is very widely used, and it is slow to reabsorb, which makes it useful where the shape of the ridge needs to be held over time.

Synthetic material (alloplast). Laboratory-made mineral, usually a calcium phosphate, which performs the same scaffolding role without any human or animal origin.

Which is used depends on how much bone is needed, where, and what the bone will have to do afterwards. If the origin of the material matters to you for personal, religious or dietary reasons, this is a reasonable question to ask before treatment and there are options in every category.

 

THE MAIN TECHNIQUES

Socket preservation is a graft placed into the socket immediately after a tooth is taken out, to limit the shrinkage that would otherwise follow. It is the simplest form, and it is done at the time of the extraction rather than as a separate operation.

Ridge augmentation rebuilds a ridge that has already become too narrow or too short, usually using graft material held in place by a membrane and sometimes small fixing pins or screws.

Guided bone regeneration is the general term for using a membrane to cover the graft. The membrane keeps the faster-growing gum tissue out while the slower-growing bone fills the space underneath.

Block grafting uses a solid piece of bone, fixed in place with small screws, where a larger volume has to be rebuilt.

Sinus lifting is a specific technique for the upper back jaw and is covered on its own page.

 

WHAT THE PROCEDURE INVOLVES

Most bone grafts are carried out under local anaesthetic, with sedation or general anaesthesia available where the case is larger or the patient prefers it.

The gum is opened to expose the bone, the area is prepared, the graft material is placed and shaped, a membrane is positioned over it if one is being used, and the gum is closed with stitches.

A small graft takes a matter of minutes. A larger reconstruction takes longer. In some cases an implant can be placed at the same time as the graft; in others the graft has to heal first before the implant can be placed.

 

HEALING

The graft material is not new bone in itself. It is a scaffold, and over the following months your own body grows into it and converts it into living bone. That process cannot be rushed.

As a general guide, a small graft placed at the same time as an implant heals alongside it, while a graft that must heal before an implant can be placed usually needs somewhere between three and nine months, depending on its size and the material used.

The first week is the part you will notice. Swelling is normal and usually peaks around the second or third day. Bruising is common. Discomfort is generally manageable with ordinary painkillers. Your dentist will give you specific instructions, which usually include eating soft food, avoiding the area when brushing, not smoking, and not disturbing the site with your tongue or finger.

 

THINGS THAT AFFECT THE RESULT

Smoking is the single most significant factor within a patient's control. It reduces the blood supply that healing depends on and is associated with a higher failure rate for grafts and implants alike.

Gum health. Grafting into a mouth with untreated gum disease is building on poor foundations, so gum treatment usually comes first.

General health. Poorly controlled diabetes, some medications — particularly certain drugs used for osteoporosis and in cancer care — and treatments such as radiotherapy to the jaws all affect how bone heals, and need to be known about and planned around before any graft is carried out.

Following the aftercare instructions, particularly in the first two weeks, while the graft is at its most vulnerable.

 

QUESTIONS PATIENTS ASK

Is it painful? The procedure itself is done under anaesthetic, so it is not painful at the time. Afterwards, most people describe soreness and swelling rather than severe pain, and ordinary painkillers are usually enough.

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Will my body reject the graft? Graft materials are processed so that they contain no living cells and cannot be rejected in the way an organ transplant can. A graft can fail to integrate — most often because of infection, smoking or movement of the site — but that is a different thing from rejection.

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Is donor or animal-derived material safe? These materials are produced under strict regulatory control and are processed to remove any biological material that could transmit disease. They have been in routine use in dentistry for decades.

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How long before I can have my implant? It depends entirely on the size of the graft. Sometimes the implant goes in at the same time. Where the graft must heal first, several months are usually needed.

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What happens if a graft fails? It can usually be redone. The reason for the failure matters, because it needs to be addressed before trying again.

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Can I avoid needing a graft? Sometimes. Having a graft placed at the time of an extraction limits the bone loss that would otherwise occur. Where bone has already been lost, there are also implant techniques designed for reduced bone volume, which may avoid the need for extensive grafting.

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