All-on-4: Full-Arch Rehabilitation on Four Implants

How the Malò protocol with tilted implants works, why it avoids bone grafting in most cases, and the real contraindications worth knowing.

The All-on-4 protocol, developed by Professor Paulo Malò based on over twenty years of research and patented in the 1990s, provides full rehabilitation of an entire edentulous arch through placement of just four implants: two anterior implants placed axially, where bone is generally better quality, and two tilted posterior implants, typically angled between 30 and 45 degrees, positioned to make use of the remaining basal bone while avoiding delicate anatomical structures such as the inferior alveolar nerve, the maxillary sinus or the nasal cavities.

The tilting of the posterior implants isn't a fallback compromise, but a precise biomechanical choice: it allows increasing the distance between the implants themselves, achieving a wider prosthetic support polygon, reducing the length of the denture's cantilever extensions, and using longer implants that increase the contact surface between bone and implant. Available literature, with follow-up ranging from 1 to 10 years across various studies, indicates that this tilting doesn't compromise the long-term results of the rehabilitation, with outcomes comparable to those achieved with traditionally parallel-placed implants.

The most significant clinical advantage of the All-on-4 protocol is the ability to avoid, in the large majority of cases, preliminary bone regeneration procedures — biologically and financially costly procedures, often operator-dependent in their results. By making use of available remaining bone, it's often possible to proceed in the same session with extraction of no-longer-salvageable teeth, implant placement, and even application of an immediately-loaded screw-retained provisional denture, restoring function and aesthetics to the patient within a single day, with the definitive denture made a few months later once osseointegration is complete.

The real contraindications to this protocol are more limited than commonly thought: bruxism and smoking are considered risk factors but not absolute contraindications, while true contraindications include uncontrolled immune system diseases, prior radiotherapy in the mandibular or maxillary region, and ongoing treatment with intravenous bisphosphonates, due to the risk of jaw osteonecrosis associated with this drug class. Implant success rates reported in the literature typically range between 97% and 99%, with prosthetic success reaching 100% in many case series.

On Oralzon you'll find dental implants for immediate-loading protocols, prosthetic components for All-on-4 rehabilitations and all the instrumentation needed for planning and executing this technique.