What Is All-on-Six Dental Implants?
A patient with failing dentition or an unstable denture searches for a permanent solution. They encounter terms like All-on-Four, All-on-Six, full-arch fixed implants, and Teeth in a Day. Among these, the All-on-Six concept stands out as a robust, comprehensive approach to full-arch rehabilitation. But what exactly does All-on-Six mean? How does it differ from other full-arch solutions? Who is it for, and what does the treatment involve?
This guide provides a thorough, detailed explanation of the All-on-Six dental implant technique. We explore the surgical and prosthetic principles, the candidacy criteria, the procedure timeline, the advantages and limitations, and the comparison with other full-arch approaches.
Defining the All-on-Six Concept
All-on-Six is a full-arch dental implant rehabilitation technique where six dental implants are placed in a single jaw to support a fixed, non-removable prosthesis. The patient receives a full arch of replacement teeth, typically on the same day or shortly after surgery, that is screwed into the implants and can only be removed by a dentist.
The Name: All-on-Six
The name describes the treatment: all teeth on six implants. It is a variation of the more widely known All-on-Four concept, with two additional implants for increased support, stability, and redundancy. The term is not a proprietary brand but a descriptive clinical designation.
The Core Principle
The fundamental idea is to replace an entire arch of missing or failing teeth with a fixed prosthesis supported by strategically placed implants. The implants are positioned to maximize the use of available bone, often with the posterior implants tilted to avoid anatomical structures and to increase the anteroposterior spread, the distance between the most anterior and most posterior implants.
The Anatomy of an All-on-Six Restoration
Understanding the components clarifies how the system works.
The Six Implant Fixtures
Six endosseous dental implants are placed in the jaw. The typical distribution is:
- Two anterior implants placed vertically, near the positions of the canines or lateral incisors.
- Two posterior implants placed in the premolar region.
- Two additional posterior implants placed in the molar region, often tilted distally to avoid the maxillary sinus in the upper jaw or the inferior alveolar nerve in the lower jaw, and to engage better-quality bone.
The exact positions depend on the patient’s bone anatomy, determined through cone-beam CT imaging and virtual implant planning software.
The Multi-Unit Abutments
After the implants are placed, multi-unit abutments are attached. These are angled connectors that screw into the implants and provide a common platform for the prosthesis. Angled abutments, typically 17 or 30 degrees, compensate for implant tilts so that the prosthetic screws emerge in positions that are accessible and that do not compromise esthetics or function.
The Fixed Prosthesis
The prosthesis is a full arch of artificial teeth, usually made of acrylic with a titanium framework, or of monolithic zirconia for a premium option. It is screwed onto the multi-unit abutments. It is fixed in place and is not removable by the patient. The prosthesis replaces all the teeth in the arch, as well as some of the lost gum and bone volume through a pink acrylic or ceramic flange that mimics the appearance of natural gum tissue.
How All-on-Six Differs from All-on-Four
The distinction is in the number of implants and the biomechanical implications.
Increased Support and Stability
Six implants provide more anchors than four. The additional implants, placed posteriorly, distribute chewing forces more broadly across the jaw. This reduces the stress on any single implant and on the bone surrounding it.
Reduced Cantilever Forces
In an All-on-Four prosthesis, the most posterior teeth are often cantilevered beyond the distal implants. This cantilever creates a lever arm that magnifies the forces on the implants. With six implants, the distal implants are positioned further posteriorly, reducing or eliminating the cantilever length. This is biomechanically advantageous, particularly for patients with heavy occlusal forces or bruxism.
Redundancy and Risk Mitigation
If one implant fails in an All-on-Four configuration, the entire prosthesis may be compromised, as only three implants remain to support a full arch. With six implants, if one fails and cannot be salvaged, five remain, which may still support the prosthesis adequately while the failed implant is addressed. This redundancy provides a margin of safety.
Bone Volume Requirements
Six implants require more bone than four, specifically in the posterior regions. Patients with significant posterior bone loss may not have adequate bone for six implants without extensive grafting. In such cases, All-on-Four or zygomatic implants may be the more feasible option.
Surgical Time and Complexity
Placing six implants is a longer surgery than placing four. The increased surgical time and complexity may be a consideration for medically compromised patients or those who wish to minimize surgical duration.
Table: All-on-Four Versus All-on-Six Comparison
| Feature | All-on-Four | All-on-Six |
|---|---|---|
| Number of implants | 4 | 6 |
| Posterior implant positions | Typically premolar region, tilted | Premolar and molar regions, tilted as needed |
| Cantilever length | Moderate | Minimal to none |
| Biomechanical stress distribution | Good | Excellent |
| Redundancy | Low (failure of one implant may compromise prosthesis) | Higher (one implant can fail without immediate prosthesis loss) |
| Bone requirement | Less, suitable for moderate resorption | More, requires adequate posterior bone or grafting |
| Surgical time | 2-4 hours | 3-5 hours |
| Cost | Lower | Higher (two additional implants and components) |
| Indication | Moderate to severe bone loss | Adequate bone for six implants, high occlusal forces, patient preference for maximum stability |
The All-on-Six Procedure Step by Step
Understanding the patient journey demystifies the treatment.
Preoperative Planning
The process begins with a comprehensive evaluation, including medical history review, clinical examination, and cone-beam CT imaging. The CB-CT data is used for virtual implant planning. The surgeon plans the exact positions of the six implants, considering bone volume, vital structures, and the prosthetic requirements. A surgical guide is fabricated to transfer the plan to the surgery.
The Surgical Procedure
On the day of surgery, the patient receives local anesthesia with sedation or general anesthesia, depending on the complexity and patient preference. Any remaining failing teeth are extracted. The bone is leveled if necessary to create a flat platform for the implants. The six implants are placed according to the surgical guide, with insertion torque verified to ensure primary stability.
Multi-unit abutments are attached to the implants. Impressions are taken, or a preoperative digital plan is used to fabricate the provisional prosthesis. A temporary, fixed prosthesis is attached to the implants the same day. The patient leaves the appointment with a full arch of functional, esthetic teeth.
The Healing Phase
The patient follows a soft diet for the osseointegration period, typically three to six months. The temporary prosthesis is not as strong as the final one and requires careful use. The implants heal and integrate with the bone.
The Final Prosthesis
After healing is confirmed, the temporary prosthesis is removed. Final impressions are taken. The dental laboratory fabricates the definitive prosthesis, which may be a titanium framework with acrylic denture teeth and pink acrylic, a titanium-composite hybrid, or a monolithic zirconia prosthesis. The final prosthesis is stronger, more durable, and more esthetic than the temporary.
The final prosthesis is screwed into place. The screw access holes are sealed. The patient receives oral hygiene instructions and a maintenance schedule.
Who Is an Ideal Candidate for All-on-Six?
Candidacy involves multiple factors.
Adequate Bone Volume
The patient must have sufficient bone in the anterior and posterior regions to accommodate six implants of adequate length and diameter. CB-CT evaluation is essential. If bone is deficient, grafting may be required, or the patient may be a better candidate for All-on-Four.
Good General Health
The patient must be healthy enough for the surgical procedure and for predictable healing. Uncontrolled systemic diseases, heavy smoking, and certain medications may affect candidacy.
Commitment to Maintenance
All-on-Six prostheses require diligent home care. The patient must be willing and able to clean under the prosthesis daily, using specialized brushes or water flossers, and attend regular professional maintenance visits.
Realistic Expectations
The patient must understand that while the All-on-Six prosthesis is a dramatic improvement, it does not feel identical to natural teeth. There is a learning curve for speech and eating. The prosthesis must be professionally removed and cleaned periodically. It is not permanent in the sense of never needing replacement; the prosthesis has a finite lifespan.
Advantages of All-on-Six
The benefits drive patient and clinician choice.
Superior Stability and Function
Six implants provide exceptional stability. Chewing function is excellent, approaching that of natural teeth. The patient can eat a wide variety of foods with confidence.
Bone Preservation
The six implants stimulate the bone at multiple points along the arch, preserving bone volume and facial structure better than fewer implants or removable dentures.
No Palatal Coverage
Unlike a removable denture, the All-on-Six prosthesis does not cover the palate. Taste is unaffected. The prosthesis is smaller and more comfortable.
Immediate Fixed Teeth
The patient leaves surgery with a fixed provisional prosthesis. There is no period of being without teeth or wearing a removable temporary denture.
High Success Rate
Full-arch implant rehabilitation with six implants has excellent long-term success rates, comparable to or exceeding All-on-Four, with the added biomechanical benefits of the additional implants.
Limitations and Considerations
Honest discussion includes the challenges.
Cost
All-on-Six is a significant financial investment. The cost of two additional implants, abutments, and the more extensive surgical procedure increases the total fee compared to All-on-Four.
Surgical Extent
The surgery is longer and more extensive. Postoperative swelling and discomfort may be greater. Patients with medical conditions that limit surgical tolerance may be better served by a less extensive procedure.
Hygiene Requirements
Cleaning under a full-arch fixed prosthesis is demanding. The patient must be meticulous. Food trapping under the prosthesis is a common complaint. Regular professional maintenance, including removal and cleaning of the prosthesis, is mandatory.
Prosthesis Wear and Replacement
The final prosthesis, while durable, is not indestructible. The acrylic teeth may wear over years. The prosthesis may fracture if overloaded. Replacement of the prosthesis is an expected future expense.
Phonetic Adaptation
The patient must adapt to speaking with a full-arch prosthesis that has a different palatal contour than a removable denture or natural teeth. Most patients adapt within weeks, but some may notice persistent minor speech differences.
Table: All-on-Six Material Options for Final Prosthesis
| Material | Advantages | Disadvantages | Approximate Longevity |
|---|---|---|---|
| Acrylic with titanium framework | Lower cost, repairable, lighter weight | Wears faster, may stain, less esthetic | 5-10 years |
| Composite with titanium framework | More wear-resistant than acrylic, repairable | Can chip, moderate esthetics | 7-12 years |
| Monolithic zirconia | Extremely strong, highly esthetic, wear-resistant | Higher cost, heavier, difficult to repair if fractured | 10-20+ years |
| Porcelain fused to zirconia | Ultimate esthetics, strong | Highest cost, porcelain can chip | 10-20+ years |
Maintenance of All-on-Six Restorations
Long-term success depends on maintenance.
Daily Home Care
The patient must clean under the prosthesis daily. A water flosser with a specialized tip, super floss with a stiff end, or interdental brushes designed for implant prostheses are used to access the space between the prosthesis and the gum. Brushing the prosthesis itself with a non-abrasive toothpaste is recommended.
Professional Maintenance Visits
Every three to six months, the patient should see the dentist or hygienist. The prosthesis may be removed for deep cleaning. The implants are probed and examined. Radiographs are taken at appropriate intervals to monitor bone levels.
Prosthesis Removal and Cleaning
At periodic maintenance visits, typically annually, the dentist unscrews the prosthesis, removes it completely, cleans it thoroughly, examines the underlying tissues and the implant abutments, and then replaces and retightens the prosthesis. This is a critical maintenance procedure for the long-term health of the implants and tissues.
Conclusion
All-on-Six dental implants provide a robust, full-arch fixed tooth replacement solution using six strategically placed implants to support a non-removable prosthesis. Compared to All-on-Four, All-on-Six offers increased biomechanical support, reduced cantilever forces, and greater redundancy. The treatment involves comprehensive planning, a single-session surgical placement of implants and delivery of a provisional prosthesis, a healing phase, and fabrication of a final, durable prosthesis. Ideal candidates have adequate bone volume, good health, and a commitment to rigorous maintenance. While more expensive and surgically extensive than All-on-Four, All-on-Six is the preferred choice for patients seeking maximum stability and those with higher occlusal demands.
Frequently Asked Questions
What is the difference between All-on-Four and All-on-Six?
All-on-Four uses four implants per arch, while All-on-Six uses six. Six implants provide greater stability, better force distribution, less cantilever, and more redundancy if an implant fails. All-on-Four is often sufficient for the lower jaw; All-on-Six may be preferred for the upper jaw or for patients with heavy bite forces.
How long does the All-on-Six procedure take?
The surgical appointment typically takes three to five hours, including extractions, implant placement, and delivery of the temporary fixed prosthesis.
Can I get All-on-Six if I have bone loss?
Some bone loss is acceptable. The tilted placement of posterior implants often avoids the need for grafting. If bone loss is severe, grafting may be required, or you may be a candidate for All-on-Four or zygomatic implants. A CB-CT scan determines this.
Is the All-on-Six prosthesis removable?
It is removable by the dentist for professional cleaning but is fixed in place and not removable by the patient. It functions like permanent teeth.
How much does All-on-Six cost compared to All-on-Four?
All-on-Six is more expensive due to the two additional implants, abutments, and increased surgical time. The cost difference varies by provider and geography, typically adding several thousand dollars per arch.
Additional Resources
American College of Prosthodontists – Full-Arch Implant Rehabilitation
https://www.gotoapro.org
Information from prosthodontic specialists on full-arch fixed implant treatment options, including All-on-Four and All-on-Six concepts.
