All-on-4 Full-Mouth Implants Explained

What All-on-4 means

All-on-4 is a treatment plan for replacing all the teeth in one jaw with a fixed set of teeth held by four dental implants. A dental implant is a small titanium post placed in the jawbone that acts like a tooth root. The idea was developed in the late 1990s by Dr Paulo Malo in Portugal, and the term "Paulo Malo technique" or "Malo protocol" is still used for this approach.

The two front implants are placed upright. The two back implants are tilted, often at about 30 to 45 degrees. Tilting lets the implant sit in denser bone further forward and be longer than a straight implant could be, which can mean fewer bone grafts in some jaws.

A single bridge of teeth is then screwed onto the four implants. Most people cannot remove it at home, unlike a denture.

Who it may suit

All-on-4 is usually considered for people who:

• have lost most or all teeth in an arch
• have teeth that cannot be saved, for example because of advanced gum disease or extensive decay
• have a loose full-arch denture or an unstable long bridge
• are healthy enough for minor oral surgery, and are willing to keep up cleaning and review visits

It is not suitable for everyone. Uncontrolled diabetes, heavy smoking, some medicines that affect bone, previous radiotherapy to the jaw, and untreated gum disease all raise the risk of implant failure and need to be discussed first.

How the plan is made

Planning starts with a medical history, an examination and X-rays. A 3D scan (CBCT) is often needed to measure bone height and width and to locate nerves and the sinuses. An OPG or CBCT scan, if needed, shows whether there is enough bone for four implants of a suitable length.

Take a common example: a patient in her sixties comes with a long upper bridge that has become loose because the gums around her remaining teeth have broken down. The scan shows that the bone in the upper jaw is thin. In a situation like this, the plan often has to change. It may include bone grafting before or during implant placement, a longer healing period, or a different number of implants. This is why the number "four" is a starting point and not a promise.

The stages

1. Assessment and planning. Examination, scans, a discussion of options and a written plan.
2. Surgery. Teeth that cannot be saved are removed, and the implants are placed under local anaesthetic, with sedation if needed. Surgery can take a few hours. If bone grafting is needed it adds to this.
3. Temporary teeth. In some cases a fixed temporary bridge is attached within a day or two. In others, especially with grafting or soft bone, a temporary denture is used while the implants heal.
4. Healing. The implants bond with bone in a process called osseointegration. This usually takes about 3 to 6 months.
5. Final bridge. Impressions are taken, the fit is tried in stages, and the final bridge is fitted. You return for adjustment of the bite.

Swelling and bruising are common after the surgery and usually settle over 1 to 2 weeks. After a graft the swelling can be more noticeable. Your surgeon will give instructions on a soft diet, cleaning around the area and medicines. The general rules for implant aftercare apply.

Risks to know about

• Infection or inflammation around an implant (peri-implantitis), which is why daily cleaning matters
• An implant that does not bond and has to be removed
• Fracture of the bridge or loosening of a screw over time
• Nerve or sinus problems, which careful planning aims to avoid
• Bone changes if cleaning is poor or if you smoke

Implant-supported teeth do not decay, but the gums and bone around them still need care. Special brushes or floss threaders are usually needed under the bridge.

Alternatives to consider

• A conventional complete denture, which is removable and needs no surgery
• An implant-retained overdenture, where a removable denture clips onto two to four implants
• More than four implants, which some jaws and some bite patterns call for
• Repairing and keeping existing teeth, where they can still be saved

Each has trade-offs in comfort, ease of cleaning, number of surgeries and time. For general information on all implant types, see dental implants and dentures.

Questions worth asking your surgeon

• Do I have enough bone, and will I need a graft?
• How many implants does my plan include, and why?
• Will I have fixed temporary teeth, or a denture, while I heal?
• What does cleaning involve, and how often are reviews?
• What happens if one implant fails?