All-on-4® explained: a full arch on four implants

What it is

All-on-4® is a way of giving you a complete row of fixed teeth, upper or lower, held by just four implants. The teeth are made as one bridge that's screwed onto the implants. It doesn't come out at night like a denture; only a dentist can remove it.

The name belongs to Nobel Biocare, which registered it as a treatment concept. In everyday use, many clinics say "All-on-4" for any four-implant full arch. That's fine, as long as you know which implants are actually being used.

How the four implants are placed

• Two at the front, usually upright, where the bone is often thickest.
• Two at the back, tilted forwards. In the upper jaw this keeps them in front of the sinus; in the lower jaw, in front of the nerve that runs through the bone.

Tilting does two useful things. A longer implant can sit in solid bone, and the back implant ends up further back in the mouth, so less of the bridge hangs out unsupported at the back.

Who it often suits

• People who have lost bone at the back of the jaw after years without teeth or with a denture
• People who'd like to avoid a bone graft or sinus lift if that's possible
• Lower jaws, where the bone at the front is usually dense
• People who want fewer implant sites and slightly shorter surgery

The limits, honestly

• Fewer supports. Each implant carries a bigger share of your bite.
• Less in reserve. If one of four implants fails, the bridge usually can't be used on three until it's replaced. What happens then.
• Upper jaws. A 2024 review of upper-jaw studies found more bone loss around implants with four than with six, although implant and bridge survival were similar.

How it compares with six

Six implants spread the load more evenly and keep more in reserve, but need more bone along the jaw. Four makes the most of limited bone, often without grafting. Large research reviews have not found a significant difference in survival between the two. All-on-6 explained · the full comparison.

Want to know what living with a full arch is like, whichever number you have? See allon6implant.co.uk for recovery, eating and cleaning in detail.

Common questions

Is All-on-4 a brand?

All-on-4® is a registered trademark of Nobel Biocare for its treatment concept. Many clinics use the phrase loosely for any four-implant full arch, with implants from various makers. Ask which implant brand and system will actually be used.

Why are the back implants angled?

Angling lets a longer implant sit in better bone in front of the sinus (upper jaw) or the nerve (lower jaw). It also moves the back support further back, which shortens the part of the bridge that sticks out unsupported.

Can All-on-4 be done without a bone graft?

Often, yes. Avoiding a graft is one of the main reasons the concept was developed. Whether you need one depends on what your 3D scan shows.

Is four implants enough for an upper jaw?

Sometimes. Upper jaws usually have softer bone, and one review found more bone loss around implants when four were used rather than six. Many upper jaws are treated well with four; your dentist should explain why four or six suits yours.

Sources

1. Nobel Biocare — All-on-4® treatment concept
2. Justia — ALL-ON-4 trademark, owned by Nobel Biocare Services AG
3. Sharaf et al. (2024), Heliyon — Four or six implants for maxillary fixed prostheses: systematic review and meta-analysis
4. Oral Health Foundation — Understanding dental implants

Checked October 2026. Where we give our own view as a clinic, we say so.