Why is a bone graft sometimes needed before a dental implant?

When a tooth is lost, the bone that held it no longer has a job to do. At this point many patients hear: “You don’t have enough bone for an implant, we need to graft.” That sounds alarming, but the explanation is simple.

What happens to the bone after a tooth is lost?

MyOMS writes that when a tooth is extracted or lost to decay or injury, the bone beneath it may shrink. A natural tooth “stimulates” the bone and keeps its volume and density, so once the tooth is gone, the bone gradually thins. Neighbouring teeth may also drift into the gap, which can lead to an uneven bite and trouble chewing. Sometimes the area looks sunken and the face looks older.

What does an implant need?

MyOMS says implants are placed in the jawbone and are made of a titanium alloy that fuses with the bone in a process called osseointegration. To be stable, an implant needs enough bone volume and density. So when there is not enough bone, the surgeon will suggest a way to add bone before the implant or at the same time. First, though, the surgeon needs to see how much bone there really is. A global consensus on treating the toothless upper jaw also names CBCT among the tools used to confirm the number of implants. Guide to jaw imaging.

What types of bone graft are there?

1. Preserving bone after an extraction. MyOMS talks about “bone preservation” and socket grafting, and describes the aim as keeping the shape, volume and density of the jaw after a tooth is removed. It writes that this supports the stability of neighbouring teeth, a healthy bite, and the success of a later implant or denture. The systematic review published in Int J Dent also names two approaches: ridge preservation after extraction and guided bone regeneration, both of which use a graft material and a membrane.

2. Sinus lift. MyOMS explains that when back teeth in the upper jaw are lost, the bone shrinks and the sinus can drop down into the empty space, so there is less bone height for an implant. In a sinus lift (sinus augmentation), the surgeon raises the floor of the sinus above the upper jaw bone. There are two main methods:

• Lateral window: an incision in the gum, a small window opened in the bone, the sinus lining lifted, graft placed, and stitches.
• Vertical osteotome: when only a little height is needed, the surgeon works through a small opening beneath the sinus.

MyOMS says it is usually done with local anaesthesia and, if needed, sedation.

What is the graft material made of?

On its sinus lift page, MyOMS says the graft can be synthetic, from an animal source, or from the patient’s own body, and the choice depends on the patient’s preference, how much bone has been lost, and the surgeon’s judgement. The Int J Dent review also writes that the choice of graft material affects the ability to build bone and the stability of the structure. Talk with your surgeon about which material suits you. If you have cultural or religious considerations, ask in advance.

How long does it take?

MyOMS says the graft fuses with the surrounding bone over “the next several months”. Sometimes the implant is placed in the same surgery, and sometimes after the graft has fully healed. MyOMS gives no exact figure, so your surgeon will tell you the timing based on your situation. After the implant is placed, MyOMS also says that fusion of the implant with the bone takes several months and there is no shortcut.

Who is a candidate for an implant?

MyOMS says that having little bone does not always rule out an implant, and an oral and maxillofacial surgeon can add bone to allow a secure placement. It writes, “If you can undergo routine dental treatment, you can generally have implants”, and that patients with high blood pressure or diabetes are usually good candidates, although some conditions call for caution. Smoking lowers the chance of implant success, but MyOMS says it does not rule out an implant. These are general statements. If your condition is not under control, you have had radiotherapy to the head and neck, or you take an osteoporosis medicine, the surgeon has to weigh the plan separately. Implants in children are also usually put off until jaw growth is complete. Whether you are a candidate is clear only after an examination and imaging.

Risks and limits of the evidence

Like any surgery, a bone graft carries risks. The systematic review of 14 randomised trials in Int J Dent shows that:

• Today’s absorbable membranes give results similar to non-absorbable ones and make the surgery less invasive.
• Titanium mesh builds more bone in complex defects but also has more complications.
• The choice of graft material affects the outcome.
• The authors point out that the studies were small, follow-up was short, and patients with underlying illness were excluded, so the results should not be applied to every patient without thought.

Guy’s and St Thomas’ also writes that an implant in grafted bone has a higher risk of failure than one in natural bone, and that a graft sometimes has to be repeated. Your surgeon should explain the risks that apply to you before the operation. After surgery, as with any mouth surgery, watch for signs of infection and bleeding. Warning signs.

What questions should you ask?

• How much bone do I have in height and width, and which scan was used to measure it?
• Is it possible without a graft? If a graft is needed, which method and which material?
• Is the graft done at the same time as the implant, or do I need to wait?
• What are the complications and the chance of failure in my case?
• Do my medical conditions or medicines, such as osteoporosis medicine, affect the plan? Medicines you should tell your surgeon about