How All-on-4 Restores Facial Height and Reduces a Sunken Appearance

There is a change that long-term denture wearers describe with a particular kind of frustration. It is not about teeth. It is that the face itself has altered — the chin appears to have moved forward and up, the distance from nose to chin has shortened, the lips have thinned and turned inward, and deep lines have formed at the corners of the mouth.

People often attribute this to ageing and try to address it with skincare or cosmetic treatment. Sometimes that helps a little. Frequently it does not, because the underlying change is not in the skin. It is structural, and it originates in the loss of the teeth and the bone that supported them.

Three separate processes are at work, and they operate on different timescales.

When your back teeth meet, they establish the height at which the jaws sit relative to one another. This is the occlusal vertical dimension, and it determines the height of the lower third of the face.

Lose the posterior teeth — or wear them down substantially — and the jaws close further than they should. The mandible rotates upwards and forwards. The chin becomes more prominent, the lower face shortens, and the whole facial proportion changes. In someone who has been without posterior support for years, the reduction can be several millimetres, which is a great deal in facial terms.

Dentures are intended to maintain this dimension, but as the ridge beneath them resorbs, the denture settles and the vertical dimension reduces again.

Alveolar bone exists for one purpose: to support teeth. Once the teeth are gone, the stimulus that maintained it is gone too, and it resorbs.

The pattern is well documented. Loss is most rapid in the first six months to a year after extraction, then continues more slowly but indefinitely. Width is lost before height. In the upper jaw, resorption proceeds upwards and inwards, so the arch becomes narrower as well as shorter. In the lower jaw, it proceeds downwards, and in advanced cases can leave very little ridge at all.

A removable denture does not slow this. If anything, the loading pattern it produces may accelerate it, which is one of the more significant long-term arguments against relying on conventional dentures indefinitely. Our article on alveolar ridge preservation explains what can be done at the time of extraction.

The upper lip rests against the front teeth and the bone behind them. The cheeks are supported from within by the posterior teeth and the alveolar ridge. Remove that scaffolding and the soft tissues fall inwards.

The visible consequences: the upper lip loses projection and the vermilion — the red part — rolls inward and appears thinner; the nasolabial folds deepen; lines form radiating from the lips; the corners of the mouth turn downwards and can become moist and irritated.

None of these are skin ageing. They are the soft tissue draping over a reduced framework.

All-on-4 describes a protocol in which a full arch of fixed teeth is supported by four implants — two placed vertically at the front and two angled posteriorly. Variations use five or six implants depending on bone volume and loading requirements.

Several features of the approach bear directly on facial appearance.

The vertical dimension can be re-established. Because the prosthesis is designed from scratch rather than adapted to an existing ridge, the height at which the jaws meet can be set deliberately. Where it has collapsed, it is restored — and with it the height of the lower face.

This is not simply a matter of making the teeth longer. Increasing the vertical dimension changes muscle length, joint position and speech, and not every planned increase is comfortable. It is therefore tested in a provisional restoration and adjusted before anything definitive is made.

Lip and cheek support is designed in. The contour of the prosthesis — the bulk of material in the flange or ridge lap area, and the position of the tooth necks — can be shaped to support the lip from behind. How much support is needed is determined by looking at the face in profile with the provisional in place, not by looking at the teeth.

Bone stimulus is partially restored. Implants transmit chewing load into bone. Where they are placed, the bone retains a functional stimulus it had lost. This does not rebuild bone that has already gone, but it changes the trajectory in the treated area.

Angled posterior implants avoid grafting in many cases. Tilting the rear implants allows longer fixtures to engage bone that remains dense — anterior to the maxillary sinus, or forward of the mental nerve in the lower jaw — without needing extensive grafting first. This is what makes fixed treatment available to many patients with advanced resorption. Our articles on All-on-4 biomechanics and All-on-4 with low bone density cover the engineering and the grafting question.

The result is fixed. A prosthesis that does not move produces different function from one that does. Chewing efficiency improves, and the muscle activity associated with stabilising a loose denture — which patients often do not realise they are doing — is no longer required.

This needs stating carefully, because this area attracts before-and-after imagery with claims attached that go well beyond what the treatment does.

Reasonably expected:

• Restoration of lower facial height where it has reduced through loss of vertical dimension.

• Improved support for the lips and the tissue around the mouth.

• Softening of the deep folds at the corners of the mouth that result from over-closure.

• Substantially improved chewing function compared with a removable denture.

• A slowing of further bone loss in the areas where implants are placed.

• Elimination of the movement, sore spots and adhesive associated with conventional dentures.

Not reasonably expected:

• Regeneration of bone that has already been lost elsewhere in the jaw.

• Correction of skin laxity, sun damage or volume loss in the mid-face, which are separate processes.

• A change to the underlying skeletal pattern.

• Appearing decades younger. The treatment restores dental structure; it does not address the rest of facial ageing.

The size of the change depends heavily on the starting point. Someone who has worn an ill-fitting denture for twenty years with substantial over-closure may see a marked difference. Someone whose vertical dimension was reasonably maintained may see relatively little, because there was less to restore.

Outcomes vary between individuals, and any assessment of likely change should be based on your own records rather than someone else's photographs.

Records. Photographs including profile views, facial measurements, and assessment of the existing vertical dimension.

Determining the correct vertical dimension. Established using a combination of methods — the freeway space at rest, speech assessment, facial proportions, and the patient's own records or older photographs where available. It is a clinical judgement supported by measurement rather than a calculation.

Provisional phase. A fixed provisional bridge is commonly placed at or shortly after surgery in All-on-4 protocols, provided the implants achieve sufficient primary stability at placement. This is where the proposed vertical dimension, lip support and tooth position are lived with and refined. Our article on 3D smile simulations covers the visual planning stage.

Definitive restoration. Made once the design is validated and integration is confirmed, typically several months later. Material options — acrylic on a metal or zirconia framework, or full zirconia — affect weight, wear characteristics and how the prosthesis is maintained. Our article on acrylic versus composite bridges compares them.

Maintenance. Fixed full arch restorations require specific cleaning and regular professional maintenance, which is set out in our article on All-on-4 maintenance and hygienist visits.

Will people notice a difference in my face?

Where vertical dimension has collapsed significantly, the change to the lower face is often noticeable. Where it has been reasonably maintained, the difference may be modest. The honest answer for any individual comes from assessment rather than from general expectation, and the provisional phase lets you see it before it is finalised.

Can implants reverse bone loss that has already happened?

No. Implants help maintain bone in the area immediately around them by restoring functional loading, but bone already lost is not regenerated by their presence. Where volume is needed for implant placement, grafting is a separate procedure with its own considerations.

Is this better than a well-made conventional denture for my face?

For maintaining vertical dimension, a fixed implant-supported restoration is more stable over time because it does not settle as the ridge resorbs. A well-made denture supports the face effectively when new; the difficulty is that the foundation beneath it continues to change. Our article on All-on-4 for long-term denture wearers covers the comparison.

How long does the treatment take?

Surgery and fitting of a fixed provisional commonly take place over a short period, often the same day where primary stability allows. The definitive restoration follows after integration, typically some months later. Timescales vary with bone quality and whether any preparatory treatment is needed.

Am I too old for this?

Age alone is not a contraindication. What matters is general health, medications, bone volume and your ability to manage the maintenance. Assessment establishes suitability individually. Our article on borderline implant candidacy covers the factors involved.

What if I have very little bone left?

Angled implant placement makes treatment possible for many patients with advanced resorption. Where it is not sufficient, options include grafting, zygomatic implants in selected cases, or an implant-retained overdenture rather than a fixed bridge. A CBCT scan establishes what is available.

Will I be able to eat normally?

Chewing efficiency with a fixed implant-supported restoration is considerably better than with a conventional denture, though it does not match a full natural dentition. There is also a period of adaptation, and some caution with very hard foods remains sensible. Our article on biting hard foods with implants covers this.

If you have noticed changes in the shape of your face since losing teeth, that observation belongs in the consultation. It changes the emphasis of the plan, because restoring facial support is a different design objective from simply providing teeth.

Photographs from before the teeth were lost are the most useful thing you can bring, and older patients often have better records than they expect.

You can contact our team to arrange an assessment at our Wimpole Street practice. Our dental implants and dentures pages describe the options.

This article provides general information and does not constitute individual dental advice. Suitability for full arch implant treatment can only be determined following clinical examination, three-dimensional imaging and review of your medical history. Implant treatment carries surgical risks and requires ongoing maintenance. Changes to facial appearance vary considerably between individuals and depend on the starting condition. Wimpole Dental is regulated by the Care Quality Commission, and our clinicians are registered with the General Dental Council.

Next review due: 12 September 2027