All-on-4 vs All-on-6: What's the Difference?

Both techniques rest on the same insight: the front of the jaw retains usable bone long after the back has resorbed, because the anterior region is denser and further from the sinus and nerve. By placing implants in that reliable bone and angling the rear ones forward, a surgeon can support a full arch without grafting the back of the jaw at all.

In both cases the implants are connected by a rigid titanium bar and a single bridge, so they function as one unit rather than as individual teeth. That cross-arch stabilization is what allows a small number of implants to carry a full arch, and it is also why a temporary bridge can frequently be delivered the same day.

So the similarities are large: same planning workflow, same CBCT and photogrammetry-driven precision, same day-of-surgery experience, same eventual look.

Four implants — two upright in the front, two angled in the premolar region — is the leaner solution. It requires less bone, fewer surgical sites, and less time in surgery, which matters for patients with medical complexity or limited tolerance for a long appointment. It is also the less expensive option, which is not a trivial consideration.

It is particularly well suited to the lower jaw, where the bone between the mental nerves is typically dense and the biting forces, while significant, are transmitted through a shorter, more favorable arch form.

The tradeoff is redundancy. With four implants, each one carries a larger share of the load, and if one is lost, the arch is more compromised than it would be with six. It also means longer unsupported spans at the very back of the bridge — cantilevers — which have to be kept conservative.

Six implants spread the same load across more sites and shorten the cantilever at the back, which reduces the leverage acting on the terminal implants. That matters most in the upper jaw, where bone is softer and less dense, and in patients with heavy bite forces or a history of bruxism.

The second advantage is repairability. If one of six implants develops a problem, the remaining five can frequently carry the arch while it is addressed. With four, the loss of one implant usually means the prosthesis has to come out of service.

Six also gives the restorative team more flexibility in how the bridge is designed and segmented, and it makes a zirconia prosthesis — heavier and more rigid than acrylic — a more comfortable engineering proposition.

The cost is real: more implants, more components, more surgical sites, and enough bone in the intermediate positions to place them properly.

It begins with a CBCT scan. Bone height and width are measured at every candidate position, along with the location of the sinus floor, the nasal cavity, and the inferior alveolar and mental nerves. Those measurements determine how many implants can be placed and where — the number follows the anatomy, not the reverse.

Bite forces come next. A patient with a strong masseter, a history of fractured teeth, or documented bruxism is a different engineering problem from a patient who has worn a denture for fifteen years and has reduced muscle bulk.

Then the prosthetic plan: how much vertical space is available, whether an acrylic or zirconia bridge is planned, and how the lip and smile line dictate where the transition from prosthesis to tissue can be hidden.

In practice, many upper arches end up with six and many lower arches end up with four, but plenty of cases go the other way for good reasons. Diamond Arch plans each arch on its own merits and shows you the imaging and the reasoning rather than starting from a number.

Surgery is performed under IV sedation. Remaining non-restorable teeth are removed, implants are placed through a 3D-printed guide derived from the digital plan, and multi-unit abutments are attached. Photogrammetry then records the exact three-dimensional position of every implant in a single capture, which is what allows a same-day bridge to fit passively rather than being torqued into place.

You leave with a fixed provisional bridge. It is not removable, you eat a soft diet on it while integration proceeds over the following months, and it functions as both a working set of teeth and a full-scale prototype of the final design.

The definitive prosthesis — usually zirconia — is delivered after integration is confirmed, refined for fit, aesthetics, and phonetics based on how you lived with the provisional.