All-on-4: Full-Arch Implant Rehabilitation
Fixed full arch on 4 implants: digital protocol with Straumann in Vitacura.
All-on-4 is a full-arch oral rehabilitation protocol that replaces an entire dental arch (upper or lower) on just 4 strategically positioned dental implants. Indicated in patients with total tooth loss, terminal dentition, or removable-prosthesis wearers seeking a fixed, functional, and stable solution.
The protocol combines two anterior implants in axial position and two posterior implants tilted approximately 30°-45°, allowing use of available bone even in patients with posterior bone resorption, avoiding or minimizing the need for bone grafts. This geometric configuration distributes chewing loads among the 4 anchors and provides sufficient primary stability for immediate load in most cases.
At Atria Sampaio we perform All-on-4 with an integrated digital protocol: cone-beam CT (CBCT) for 3D bone volume analysis, iTero 5D intraoral scanning, virtual planning with guided-surgery software, in-clinic surgical-guide printing on Phrozen Sonic Mini 8KS or Formlabs 4B, and Straumann (Switzerland) implants with SLActive surface. The fixed provisional prosthesis is designed with Exocad before surgery and installed the same day.
The patient enters the consultation with compromised dentition, pain, or removable prosthesis, and leaves with a complete arch of fixed teeth on the implants. Chewing function, aesthetics, and speech are restored in a single surgical session. The definitive prosthesis is fabricated at 3-4 months, once osseointegration is confirmed.
All-on-4 has specific contraindications and we evaluate them before proposing the protocol: active untreated periodontal disease, severely compromised bone quality, severe uncontrolled bruxism, uncompensated systemic conditions. When the case doesn't qualify, we evaluate alternatives like All-on-6, more-implant rehabilitation, or implant-supported overdenture.
Benefits
- ✓Fixed full arch on just 4 implants
- ✓Straumann implants with SLActive surface
- ✓Generally without need for bone graft thanks to posterior tilting
- ✓Immediate load: fixed prosthesis on the day of surgery
- ✓Recovery of function, aesthetics, and speech in a single session
- ✓Digital guided surgery with in-clinic-printed guide
- ✓Fixed definitive solution, not removable
- ✓NYU College of Dentistry academic standard
Our Approach
The process starts with comprehensive evaluation: clinical exam, periodontal evaluation, clinical photography, iTero 5D intraoral scan, and cone-beam CT for bone volume analysis at anterior and posterior sites. We digitally plan the exact position of the 4 Straumann implants (2 anterior axial + 2 posterior tilted) considering inferior dental nerve trajectory, maxillary sinuses, and available prosthetic space. We design the fixed provisional prosthesis with Exocad before surgery. We fabricate the surgical guide with Phrozen Sonic Mini 8KS or Formlabs 4B. On surgery day: extraction of any remaining teeth, bone regularization, guided installation of the 4 implants, torque and primary stability verification, and installation of the screw-retained fixed provisional prosthesis the same day. Postoperative with soft diet 4-6 weeks, follow-up at 7-10 days, 6 weeks, and 3 months. The definitive prosthesis is designed and fabricated between months 3 and 4 once osseointegration is confirmed.
Frequently Asked Questions
What exactly is All-on-4?
It's a protocol for full-arch rehabilitation (upper or lower) on just 4 dental implants. Two implants in axial position in the anterior zone, two implants tilted approximately 30°-45° in the posterior zone. A fixed prosthesis is screwed onto the 4 implants, replacing all teeth in that arch.
Why only 4 implants instead of more?
The geometric configuration with tilted implants leverages available bone and distributes chewing loads in a biomechanically stable way. Clinical studies show success rates comparable to protocols with more implants, with less surgical invasiveness, less treatment time, and generally without need for bone graft. In cases with special requirements we evaluate All-on-6 or other protocols.
Is bone graft required beforehand?
In most cases, no. Posterior implant tilting (30°-45°) avoids the maxillary sinus zone in the upper arch and the inferior dental nerve trajectory in the mandible, leveraging available bone without need for regeneration. In cases of severe resorption, prior grafting may be required.
How long does the surgery take?
Approximately 2-3 hours per arch, under local anesthesia with or without conscious sedation per patient preference. If both arches are rehabilitated (full arch upper + lower), we typically plan two separate sessions to optimize recovery.
Can I eat normally after All-on-4?
During the first 4-6 weeks we require soft diet to protect osseointegration. After that period, and especially once the definitive prosthesis is installed, you regain full chewing function for normal eating including hard and fibrous foods. All-on-4 biomechanics are designed to support normal chewing loads.
How long do the implants and prosthesis last?
Straumann implants have documented survival rates exceeding 95% at 10 years with proper care. The definitive prosthesis (titanium + porcelain or zirconia on titanium framework) has an expected useful life of 15-20 years or more, with possibility of periodic maintenance. Patient hygiene and care are determining factors for longevity.
What's the difference from a traditional denture?
A traditional denture is removable, rests on gum and bone, tends to loosen, doesn't stop bone resorption, limits chewing force, and many patients report social insecurity. All-on-4 is a fixed prosthesis screwed to the implants, doesn't move, maintains bone stimulation through the implants, recovers 80-100% chewing force, and provides the confidence of fixed teeth.