All-on-4 versus All-on-6: what actually differs

All-on-4 and All-on-6 both describe a fixed, implant-supported prosthesis replacing a full arch of teeth. The number in the name refers to how many implants support that prosthesis. It is tempting to assume that six implants must be a stronger, more reliable choice than four simply because it is a larger number — but that is not how the decision is actually made, and the published evidence does not straightforwardly support it either.

What both concepts describe

In both approaches, a full arch of implants (a top or bottom jaw with no natural teeth remaining, or none suitable for reconstruction) is replaced with a fixed bridge or denture attached to implants rather than to individual teeth. All-on-4 typically places four implants, often angled to make use of the available bone at the back of the jaw without needing a bone graft. All-on-6 places two additional implants, generally intended to distribute the load of the prosthesis across more support points. Both are variations of full-arch implant-supported rehabilitation, not two different treatments for different problems.

Is six always stronger? Report the evidence, don't assert it

A systematic review and meta-analysis published in 2026 (Shao, Chen, Wang, et al., “All-on-4 and All-on-6 implant-supported fixed prostheses for the edentulous jaw: a systematic review and meta-analysis”, International Journal of Oral and Maxillofacial Surgery, 2026), which pooled data from 55 studies identified through PubMed, Web of Science, Embase and the Cochrane Library, found the following pooled implant survival rates:

The same review reported marginal bone loss of 0.77 mm (All-on-4) versus 0.85 mm (All-on-6) at short-term follow-up, rising to 1.28 mm versus 0.94 mm at five years, and pooled mechanical complication rates of 5.91% (All-on-4) versus 6.64% (All-on-6). The authors' own conclusion was that the two techniques showed similar outcomes overall, but that this conclusion “should be interpreted with caution due to the high heterogeneity among studies” — meaning the studies pooled together varied enough in design, patient selection and follow-up that a single confident verdict is not warranted. Read plainly: the current evidence does not show that six implants reliably outperforms four, and it does not show the reverse either. Anyone telling you one number is categorically superior to the other is going beyond what this evidence supports.

What a clinician actually weighs

The number of implants placed in a full-arch case is a decision made from several factors together, not from a fixed rule: the volume and distribution of bone across the arch (which is rarely uniform), the position and primary stability achievable for each implant, the design of the planned prosthesis and how its load will be distributed, whether the arch is upper or lower (they behave differently under load), your bite and the position and force of your opposing teeth, whether you have a history of bruxism (tooth grinding, which increases mechanical load on any prosthesis), how easily you will be able to clean around the implants and prosthesis afterwards, and other patient-specific risk factors including bone quality and general health. Two patients missing the same teeth can reasonably end up with different implant numbers because their anatomy and risk profile differ.

When fewer implants may be considered, and when more may be

Fewer implants, angled to engage available bone, can sometimes avoid the need for a bone graft and shorten treatment — this is part of the original rationale for the All-on-4 approach. More implants can distribute load across a wider base, which some clinicians favour where bone quality is compromised, where bruxism is present, or where a heavier or longer-span prosthesis is planned. Neither of these is a universal rule; both are considerations a clinician weighs against your own scan and bite assessment.

The question to ask

Given the above, the useful question is not “which is better, four or six?” — the evidence does not support a general answer to that question. The useful question is: “why four (or six) for my anatomy and this specific prosthetic plan?” A clinician who can answer that by reference to your bone volume, distribution and bite is giving you a case-specific answer. A clinic that quotes a fixed number before reviewing your imaging is giving you a marketing default.

Ask to see the prosthetic plan

The number of implants is only one part of the plan. Ask to see, or have described in writing, the material of the provisional (temporary) prosthesis you will wear immediately after surgery, the material of the definitive (final) prosthesis, whether the final prosthesis is designed to be removed by a dentist for maintenance or is permanently fixed, how you will clean around it day to day, and what the plan is for repair if a component fractures or wears. These questions apply equally whether the plan involves four implants or six, and a case that has not addressed them is not yet a complete plan.

“Teeth in a day” is not the same as finished treatment

Full-arch cases are often marketed as “teeth in a day,” referring to fitting a temporary fixed prosthesis on the day implants are placed. This is a real and well-established technique, but the prosthesis you leave the clinic wearing on that day is, in the great majority of cases, a temporary one — designed to protect the healing implants and give you function while the bone integrates, not the final, permanent restoration. Ask exactly what you will be wearing when you leave, how long that temporary is expected to last, and when and how the definitive prosthesis will be fitted, including whether that requires a further visit to Turkey.

It is also worth asking whether the number proposed is fixed regardless of outcome, or whether your clinician would adjust it — adding an implant, or placing fewer than planned — if the intraoperative findings differ from what the scan suggested. A plan that allows for that kind of adjustment, explained to you in advance, reflects planning around your anatomy rather than a package sold before your imaging was reviewed.

What to do next

Before agreeing to an All-on-4 or All-on-6 plan, ask your treating clinician to explain, by reference to your own CBCT scan and bite assessment, why that number of implants suits your anatomy — not as a general comparison between the two approaches. Ask to see the prosthetic plan in writing, including provisional and definitive materials and the maintenance routine. You can check whether a facility holds a Ministry of Health authorisation for treating international patients through the dental register, and our broader guide to dental implants in Turkey covers the components, planning and failure questions that apply to any implant case, full-arch or otherwise. If you are still assessing several clinics, how to compare clinics sets out what to look at beyond the number of implants quoted.