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The All-on-4 concept was developed by Paulo Maló and formalised in collaboration with Nobel Biocare in the early 2000s. It addressed a specific clinical problem: patients with full-arch tooth loss and partial bone resorption who required a fixed prosthesis but whose bone anatomy made conventional complete implant placement across the arch impractical without extensive grafting. Maló’s solution was to place four implants per arch in strategically selected positions — two anterior implants in the anterior maxilla or mandible, and two posterior implants angled at 30–45 degrees — achieving adequate AP spread and primary stability across a range of bone presentations without sinus augmentation in the upper jaw.
At Dazzle Dental Clinic, the All-on-4 concept is the foundation of full-arch implant rehabilitation. The specific protocol used, the implant systems employed, and the prosthetic design have evolved from the original Maló protocol — but the core mechanical principle remains.
The Core Mechanism: Why Angled Posterior Implants Work
The angled posterior implants in All-on-4 serve two functions. First, they place the implant apex in denser bone anterior to the sinus in the upper jaw. Second, they increase the effective AP spread: the further apart the posterior implants are (measured along the arch), the greater the mechanical stability of the prosthetic bridge and the shorter the distal cantilever. For a detailed biomechanical explanation of how AP spread and angulation are planned at Dazzle, see our All-on-4 strategic implant placement guide.
The Prosthetic Options: What the All-on-X Bridge Is Made Of
Acrylic-on-metal (hybrid prosthesis): The original Maló protocol prosthesis was an acrylic bridge with a metal framework. The metal framework provides stiffness to prevent prosthetic fracture; the acrylic teeth provide the aesthetic surface. Advantages: lighter, easier to repair, lower cost. Limitations: acrylic teeth wear over years.
Monolithic zirconia: Milled from a single block of zirconia, providing the highest strength and best aesthetic consistency across the full arch. At Dazzle, monolithic zirconia bridges are the preferred final prosthesis for full-arch cases — fabricated in the in-house CAD/CAM laboratory from the intraoral scan. The bridge is custom-designed to the patient’s individual arch morphology and emergence profile. For the detail on zirconia vs E.max material selection, see our prosthetic materials guide.
PFM (porcelain-fused-to-metal): Full-arch metal framework with individual porcelain-fused facings. Risk of porcelain fracture from the metal substructure under sustained occlusal load. Less commonly specified at Dazzle for new cases; retained for specific legacy cases.
How the Protocol Has Evolved at Dazzle
The core four-implant configuration remains, but the clinical protocol has incorporated several advances: digital implant planning replaces freehand placement (implant positions are virtually planned from CBCT before surgery and executed with a 3D-printed surgical guide); intraoral scanning replaces physical impressions for the prosthesis design; and same-day monolithic zirconia provisional fabrication in the in-house laboratory is standard for international patients.
FAQs
Q1: Is All-on-4 the same as All-on-6?
The same concept with a different number of implants. All-on-6 adds two additional implants — typically one per side, in the posterior position — which shortens the distal cantilever and improves load distribution. All-on-6 is preferred when bone volume allows additional implants, when the patient has heavy bite forces, or when the All-on-4 AP spread would produce an unacceptably long cantilever.
Q2: How is the prosthesis attached to the implants?
Via screws that pass through the prosthetic bridge and thread into the implant abutments. The screw access holes are in the palatal or occlusal surface of the bridge, covered with composite. The bridge is screw-retained, not cemented — this allows retrieval for maintenance, repair, or replacement without damaging the implants.
Q3: Can the bridge be removed for cleaning?
The bridge is screw-retained and is not intended for patient removal. It can be removed by the dentist at maintenance appointments for inspection and cleaning of the tissue surface. At home, patients use interdental brushes, water flossers, and specialised implant-cleaning brushes to clean under the prosthesis at the gum margin.
Q4: What happens to the bridge if an implant fails?
If a single implant fails in a four-implant case, the bridge loses one of its four supports. Whether the remaining three implants can maintain the bridge depends on where the failure occurred and the load distribution. In most cases, the failed implant is removed and the prosthesis is supported on the remaining three implants temporarily while the replacement implant is placed and integrated.
