All-on-4 and All-on-6 Full-Arch Dental Implants

Quick summary

All-on-4 is a technique for replacing an entire arch of missing or failing teeth with a single fixed bridge supported by four dental implants — two placed vertically at the front of the jaw and two angled (tilted) toward the back. The variant called All-on-6 uses six implants per arch and is preferred when bone volume and budget allow it.

It is one of the most life-changing procedures in modern dentistry for patients who have lost most or all of their teeth. It is also one of the most aggressively marketed, which makes it especially important to understand what the technique can and cannot do.

What All-on-4 actually means

The name describes a configuration: four implants per arch supporting a single multi-unit bridge. The two posterior implants are deliberately tilted backward to anchor in denser, more available bone and to avoid anatomical structures such as the maxillary sinus and the inferior alveolar nerve. Tilting also lengthens the prosthetic base, which means the bridge can be cantilevered slightly further back without biomechanical penalty.

"All-on-4" was popularized as a branded protocol but the underlying concept — using tilted distal implants to avoid grafting in atrophic jaws — predates the brand and is used by many clinicians under generic names like "tilted-implant full-arch" or "fixed hybrid prosthesis."

Compared to dentures and individual implants

Who is a candidate?

The technique is designed for patients who are missing all the teeth in an arch, who have most of their remaining teeth slated for extraction, or who are wearing a conventional full denture they cannot tolerate. Key considerations:

• Sufficient bone in the anterior jaw to anchor the front implants vertically.
• Sufficient bone behind the canines to anchor the tilted distal implants — usually evaluated with CBCT.
• Periodontal status of any remaining teeth: untreated active disease should be addressed first.
• General health that permits surgery and healing — particularly diabetes control, smoking status, and any bone-modifying medications.
• Realistic expectations and willingness to commit to lifelong professional maintenance.

The clinical workflow

Planning

Records include CBCT, intraoral scan or impression, facial photographs, and a bite registration. Implant positions are planned digitally with the future bridge as the starting point — restoratively driven planning. A surgical guide is often printed.

Surgery day

Performed under local anesthesia, often with IV sedation. Any remaining teeth in the arch are extracted, the bone is contoured, four implants are placed (two anterior, two tilted distal), multi-unit abutments are attached, and a temporary acrylic bridge is screwed onto the implants the same day in most cases. The patient leaves with fixed teeth.

Healing

Soft diet for several weeks, then progressively normal eating. The temporary is designed to keep loading within a range the integrating implants can tolerate.

Definitive bridge

After approximately 3–6 months of osseointegration, a new impression is taken and the definitive bridge is fabricated — most often in monolithic or layered zirconia, or as a hybrid of acrylic teeth on a milled titanium bar. This visit may take place in stages with try-ins.

The bridge itself: materials and trade-offs

Acrylic on titanium

A milled titanium bar with denture teeth and pink acrylic gum work bonded onto it. Lighter, easier to repair chairside, and historically less expensive. The trade-off is that acrylic and denture teeth wear and chip over time, and the prosthesis often needs significant refurbishment within 5–10 years.

Monolithic zirconia

The whole bridge is milled from a single block of zirconia, then characterized and glazed. Extremely durable and stain-resistant. Chipping is much less common but, when it happens, the bridge usually needs to be sent back to a laboratory rather than repaired chairside. Generally a higher upfront cost with a longer expected lifespan.

Layered or hybrid zirconia

Zirconia framework with layered porcelain on the visible surfaces. The most aesthetic option, with translucency closer to natural teeth, but porcelain layering is the most chip-prone of the three approaches.

Risks and complications

Surgical

• Infection at one or more implant sites.
• Failed osseointegration of one of the four implants — particularly impactful in a four-implant design.
• Nerve injury, sinus communication, or bleeding events, as with any implant surgery.

Prosthetic

• Screw loosening or fracture, especially in heavy bruxers.
• Chipping of the bridge material, particularly with layered porcelain.
• Wear of opposing natural teeth or opposing dentures.

Biological, long-term

• Peri-implant mucositis and peri-implantitis, especially in patients with prior periodontitis or inadequate hygiene.
• Bone loss around individual implants, eventually compromising the prosthesis.

Living with a full-arch bridge

• Daily cleaning with a water flosser, implant-specific floss, and interdental brushes.
• Professional hygiene every 3–6 months — many full-arch patients are placed on a 3–4 month interval indefinitely.
• Periodic bridge removal (typically yearly) by the clinician to clean underneath, inspect components, and replace prosthetic screws.
• A nightguard for patients with bruxism — overload is the most common mechanical cause of failure.

Questions to ask a surgeon

• Why four implants and not six, in my specific case?
• What is your protocol if one implant fails to integrate?
• Will the definitive bridge be acrylic-on-titanium, monolithic zirconia, or layered, and why?
• Is the definitive bridge included in the quoted fee, or only the temporary?
• How often will you need to unscrew the bridge for maintenance?
• What is the warranty on the implants and on the prosthesis?
• How many full-arch cases of this type do you complete per year?

Frequently asked questions

References and further reading

1. Maló P, et al. The All-on-4 treatment concept — long-term clinical outcomes. Clinical Implant Dentistry and Related Research.
2. Academy of Osseointegration. Position statements on immediate loading of full-arch prostheses.
3. International Team for Implantology. ITI Treatment Guide on edentulous arch rehabilitation.
4. European Association for Osseointegration. EAO Consensus Conference Proceedings on full-arch rehabilitation.
5. Schwarz F, et al. Peri-implantitis consensus reports. Journal of Clinical Periodontology.
6. Cochrane Oral Health Group. Systematic reviews on interventions for replacing missing teeth.