All-on-4 vs All-on-6: How the Procedures Differ

Schematic only, not to scale — illustrates typical implant positioning, not a specific patient plan.

Planning: the CBCT scan comes before everything else

Before any surgical decision is made, a cone-beam CT (CBCT) scan gives a clinician a three-dimensional picture of your jaw — bone height, width and density at each proposed implant site, and the exact position of structures such as the maxillary sinus and the mandibular nerve canal. This scan, together with a clinical examination, is what the treatment plan is built around: how many implants, where each one sits, and at what angle. See bone loss & bone grafting for how bone quantity and quality specifically shape this plan. A treatment plan proposed without a CBCT scan having been reviewed is a reasonable thing to question, for either configuration.

Implant positioning: tilted vs upright placement

The defining structural feature of the All-on-4 concept, first described in the implant literature by Paulo Maló and colleagues, is that the two rear implants are placed at an angle — often up to around 45° — rather than straight down. Angling lets the implant travel further forward through the jaw before it exits the bone, engaging denser anterior bone and routing around the sinus or nerve canal in anatomy where that is possible, while also shortening the unsupported cantilever at the back of the bridge compared with a straight implant placed further back. All-on-6 typically distributes six implants more evenly along the arch, with the rearmost implants usually placed more upright, putting a fixture more directly beneath the molar region; angled placement is sometimes used for the rearmost implants here too, but the wider, more even spread is the main structural difference. Neither angling nor implant count alone determines how a case turns out — placement accuracy, planning and post-surgical management all contribute meaningfully.

Surgery day: what actually happens

The surgical workflow is broadly similar for both procedures, and is typically carried out under local anaesthetic, with intravenous sedation offered as an option at many clinics:

1. Final review of the CBCT-based digital plan.
2. Removal of any failing or remaining teeth in the arch, where clinically appropriate.
3. Preparation of each implant site and placement of the implants — four for All-on-4, six for All-on-6 — following the pre-surgical plan.
4. Assessment of primary stability at each implant site, which determines whether immediate loading is appropriate.
5. Attachment of a provisional bridge, where clinical criteria allow, usually the same day or within a few days.
6. A healing period, commonly around 3–6 months, before the final bridge is fitted.

The main practical difference on the day is time and surgical scope: All-on-6 involves two additional osteotomies (implant sites) to prepare and two more implants to place, which typically adds to overall theatre time compared with All-on-4. That can mean somewhat more post-operative swelling for some patients, though recovery from either procedure is generally described as broadly comparable in the days that follow — see recovery for what that period typically involves.

Immediate loading: a conditional outcome, not a guarantee

"Teeth in a day" is one of the most attractive claims in full-arch implant marketing, and one of the most commonly overstated. Immediate provisional teeth may be possible when adequate primary stability and other clinical criteria are met at the time implants are placed — this is assessed implant by implant, in theatre, using measures a surgeon checks during surgery itself, not decided or promised in a consultation beforehand. Where primary stability is not achieved for one or more implants — which can happen even with careful planning, particularly in softer bone — a clinician may delay loading part or all of the arch, or use a removable interim solution while healing proceeds, to protect the outcome. This applies equally to All-on-4 and All-on-6: implant count does not itself guarantee that immediate loading criteria will be met, and no honest source can promise a same-day fixed bridge to a specific patient before surgery has taken place.

Provisional bridge vs final bridge

Where immediate loading criteria are met, a provisional (temporary) bridge is fitted at or shortly after surgery. It is typically constructed to be lighter and more easily adjusted than the final restoration, and its purpose is to protect the implants during healing while still giving functional, reasonably natural-looking teeth. Some months later — once healing and osseointegration are confirmed — the provisional is replaced with a final bridge, generally a more durable, definitive restoration. Material choice for both stages (commonly acrylic-on-titanium for the provisional, and acrylic or zirconia for the final bridge) affects durability, maintenance and cost; see prosthesis & materials for the fuller comparison of these options.

Number of visits and overall timeline

For patients travelling for treatment, two visits are the typical pattern: a first trip — often around 5–10 days — for the CBCT scan, surgery and provisional bridge, and a second trip — often around 5–7 days — some months later for the final bridge. Some clinics offer accelerated single-trip protocols for suitable cases, though not every case is suited to this. The table below summarises the typical stages; individual timing varies by patient, bone healing and clinic protocol, and is not a fixed schedule for any specific reader.

Notably, the treatment timeline does not differ meaningfully between All-on-4 and All-on-6 in most cases — what changes is the surgical scope and time on the day itself, not the overall calendar of visits.

How four- and six-implant surgery actually differ — and where they don't

• Differs: number of implant sites prepared and fixtures placed (four vs six).
• Differs: total surgical time, generally somewhat longer for All-on-6 to accommodate the additional sites.
• Differs: how often grafting or a sinus lift is discussed for the posterior sites, since upright rear implants generally need more bone height than tilted ones — see bone loss for the fuller explanation.
• Doesn't differ: the overall workflow — CBCT planning, provisional bridge (where criteria allow), healing period, final bridge.
• Doesn't differ: the typical number of visits or the broad treatment timeline for most cases.
• Doesn't differ: whether immediate loading is available in principle — it is conditional on primary stability for either configuration, not guaranteed by implant count.

Which configuration actually suits a given patient depends on bone volume and density, bite force and whether bruxism is present, and arch length — not on which procedure sounds more comprehensive. See who needs which for the fuller, non-diagnostic decision framework.

Deciding which procedure is right for your own case

None of the above can be turned into a decision for a specific reader from a page alone — that depends on a CBCT scan and a clinical examination of your own bone, bite and jaw. Our disclosed clinical partner, Taki Dent in Antalya, reviews CBCT imaging as part of a remote case assessment; further detail on requesting one is available on get a clinical assessment.

Frequently asked questions

For how bone volume and quality shape implant positioning, see bone loss & bone grafting. For what recovery generally involves after surgery, see recovery. Return to the All-on-4 vs All-on-6 comparison home page for the full overview.