All-on-4 and All-on-6 Implants

All-on-4 and All-on-6 are implant methods used to replace all the teeth in a jaw with a fixed set of teeth. Instead of placing a separate implant for each missing tooth, 4 or 6 implants are placed in the jaw and the whole set of teeth is screwed onto them. The name says exactly this: all the teeth, on 4 or 6 implants.

The resulting set of teeth is not taken out at night like a denture, needs no adhesive and does not cover the palate. It can only be removed by the dentist for check-ups and cleaning.

An important feature of this method is that the implants at the back are placed at an angle. After tooth loss, the sinus in the upper jaw and the nerve supplying the lip in the lower jaw may leave no room for implants at the back. When the back implants are tilted to avoid these structures, longer implants can be used in most patients without extra bone surgery, and the teeth are supported over a wider area.

• People with no teeth left in one jaw
• People whose teeth cannot be saved because of advanced gum disease, decay or fractures
• People who struggle with a loose, rubbing denture or with chewing
• People for whom individual implants have become difficult because bone has been lost at the back

The general requirements for implants also apply here: adequate general health, systemic conditions under control and good oral hygiene during healing. Uncontrolled diabetes, radiotherapy to the head and neck, certain osteoporosis medicines and heavy smoking are assessed before treatment (details on the Dental Implants page).

Bone loss in the upper jaw can be so advanced that there is not enough bone even for angled implants. In that case, zygomatic implants, which are anchored in the cheekbone, are considered as an option.

The idea behind both is the same; the difference is the number of implants supporting the teeth.

All-on-4

• 4 implants are placed in the jaw: usually 2 straight at the front and 2 angled at the back.
• It is preferred for patients with reduced bone volume, especially when bone at the back is insufficient.
• It means fewer implants and shorter surgery; in most cases no extra bone surgery is needed.

All-on-6

• 6 implants are placed in the jaw; chewing forces are spread over more implants.
• It is preferred for patients with enough bone for 6 implants.
• If a problem arises with one of the implants, there is more support left to carry the teeth.

Which one is suitable is decided by looking at the amount and quality of bone on a 3D CT scan, the teeth in the opposite jaw and chewing habits. Neither is always "better"; the right choice is the one that suits that jaw.

With individual implants, bone healing is usually awaited. With All-on-4 and All-on-6, however, when the implants are joined together by a fixed temporary set of teeth, chewing forces are spread across all of them rather than one. So if the implants are firmly seated when they are placed, temporary fixed teeth can be fitted the same day or within a few days.

This decision is made during the operation. If the initial stability of the implants is not sufficient, healing is safely awaited and the patient is not left without teeth; a temporary denture is used. The permanent set of teeth is made after the implants have bonded with the bone, usually within 3–6 months.

1. Examination and 3D CT scan. Your general health, medicines and expectations are discussed. The CT scan measures the bone and shows where the sinus and nerves are. The teeth in the opposite jaw and the bite are assessed.
2. Planning. The number, positions and angles of the implants are planned. The length and colour of the teeth and the smile line are discussed; an impression or digital scan is taken for the temporary teeth.
3. Operation. Under local or general anaesthesia, any teeth that need removing are extracted, the jaw is cleaned and the implants are placed. The type of anaesthesia is decided together, based on your condition and preference.
4. Temporary fixed teeth. In suitable cases, a temporary set of teeth is screwed onto the implants the same day or within a few days.
5. Healing period. While the implants bond with the bone, you eat soft foods and attend check-ups.
6. Permanent set of teeth. When healing is complete, a new impression is taken, a try-in is done and a permanent set of teeth made from a more durable material is fitted.

• Compared with a denture: The teeth are fixed; they do not move or rub and need no adhesive or removing at night. In the upper jaw the palate is not covered, so taste and speech are less affected. Chewing is usually clearly better than with a denture. On the other hand, it requires surgery and costs more.
• Compared with an implant for each tooth: Fewer implants are used and, when bone at the back is insufficient, extra bone surgery is often not needed; time and surgical load are reduced. On the other hand, the teeth are made as one unit rather than individually; if one part has a problem, the whole set is removed for repair.
• An implant-supported removable denture is also an option: This denture clips onto attachments on 2–4 implants but can be taken out by the patient, and is more economical than a fixed set of teeth. Which option suits you is discussed together at the examination.

This treatment is more extensive than a single implant. Expected and possible problems:

• Swelling, bruising, pain and limited mouth opening in the first days (expected and temporary)
• One of the implants not bonding with the bone; since the teeth would then have less support, re-planning is needed
• The temporary teeth breaking on hard foods during healing
• Changes in lip sensation near the nerve in the lower jaw, or sinus-related problems in the upper jaw
• Temporary changes in speech and biting while getting used to the new teeth in the first weeks
• Over the years, gum inflammation and bone loss around the implants (peri-implantitis)

Because the teeth are fixed, cleaning them is different from cleaning a denture and needs care. Daily cleaning and regular check-ups are the most effective way to prevent most long-term problems.

• First 48–72 hours. Swelling and tenderness are at their peak. Cold compresses, the recommended medicines and rest. Choose liquid, lukewarm foods that need no chewing.
• First week. Soft foods such as soup, purée and yoghurt. Avoid smoking, hot drinks and vigorous rinsing. Any stitches are removed on day 7–10.
• First 2–3 months. While the implants heal, avoid biting into food with the temporary teeth and avoid hard foods (nuts, hard bread crusts, meat on the bone); cut food into small pieces.
• After the permanent teeth. Return to a normal diet. Daily brushing, interdental brushes or a water flosser, and regular check-ups. At check-ups the teeth are removed when necessary to clean around the implants.