What are the differences between All-on-4, All-on-6, and Malo Bridge dental implant systems? Which is best for full mouth rehabilitation?

Patient Question

Rajiv Mehta 🇮🇳: Dr. Samuel, I’ve lost most of my teeth due to severe periodontal disease and I’m exploring full mouth rehabilitation options. My dentist has mentioned All-on-4, All-on-6, and Malo Bridge implant systems. I’m confused about the differences between these options. What are the pros and cons of each? I’ve heard that All-on-4 is more affordable but All-on-6 might be more stable long-term. Also, what materials are used for the prosthetic teeth? I’m concerned about durability since this is a significant investment. I’m 58 years old and want a solution that will last. As an international patient potentially traveling for treatment, what factors should I consider?

Dr. Rockson Samuel’s Response

Dr. Rockson Samuel: Thank you for your thoughtful question, Rajiv. Full mouth rehabilitation with implant-supported fixed prostheses is indeed a significant investment, both financially and in terms of your oral health future. Let me comprehensively address the differences between All-on-4, All-on-6, and the Malo Bridge systems to help you make an informed decision.

Understanding the “All-on-X” Concept

The “All-on-X” terminology refers to full-arch rehabilitation systems where “X” represents the number of implants supporting an entire arch of fixed prosthetic teeth. This concept revolutionized implant dentistry by offering edentulous (toothless) patients or those with terminal dentition a fixed alternative to removable dentures.

Core Principles of All-on-X Systems

All these systems share some fundamental principles:

1. Strategic Implant Placement: Implants are positioned to maximize available bone and avoid anatomical structures like the maxillary sinuses or mental foramina
2. Immediate Loading: In many cases, a temporary fixed prosthesis can be attached within 24-48 hours after implant placement
3. Tilted Posterior Implants: Posterior implants are typically angled to provide better support and avoid the need for bone grafting
4. Cross-Arch Stabilization: The prosthesis connects all implants, creating a rigid, stable structure

All-on-4 System: The Original Protocol

Developed and popularized by Nobel Biocare in collaboration with Dr. Paulo Malo, the All-on-4 system has the most long-term research supporting it.

Key Features of All-on-4:

• Number of Implants: Four implants per arch (typically titanium)
• Implant Distribution: Two vertical anterior implants and two tilted posterior implants (angled up to 45°)
• Cantilever Length: Typically supports 10-12 teeth per arch with posterior cantilevers of 10-15mm
• Bone Requirements: Minimal, often avoiding the need for bone grafting

Advantages of All-on-4:

1. Cost-Effective: Fewer implants reduce overall costs
2. Reduced Surgical Complexity: Often doesn’t require bone grafting, sinus lifts, or nerve repositioning
3. Faster Treatment Timeline: Usually allows for immediate loading with a provisional prosthesis
4. Well-Documented: Extensive clinical research with 15+ year follow-up studies
5. Less Invasive: Fewer implants mean fewer surgical sites and potentially faster healing

Limitations of All-on-4:

1. Biomechanical Stress: Greater forces on each implant, especially in patients with strong bite forces
2. Implant Failure Impact: If one implant fails, the entire prosthesis may be compromised
3. Cantilever Stress: Longer cantilevers may lead to prosthesis fracture or implant overloading
4. Limited Backup Support: No redundancy if an implant fails to integrate

All-on-6 System: Enhanced Support and Distribution

The All-on-6 concept evolved from All-on-4, adding two additional implants for increased support.

Key Features of All-on-6:

• Number of Implants: Six implants per arch
• Implant Distribution: Typically four anterior implants placed vertically and two posterior implants tilted
• Cantilever Length: Generally shorter cantilevers (5-10mm) with 12-14 teeth per arch
• Bone Requirements: May still avoid major grafting but might require more available bone than All-on-4

Advantages of All-on-6:

1. Better Load Distribution: Forces are spread across more implants, potentially extending prosthesis lifespan
2. Redundant Support: The system can often still function effectively even if one implant fails
3. Reduced Biomechanical Stress: Less strain on each individual implant
4. Shorter Cantilevers: More implants allow for better posterior support with shorter cantilevers
5. Better Suited for Higher Force Applications: Better option for patients with heavy bite forces or bruxism

Limitations of All-on-6:

1. Higher Cost: More implants and potentially more complex surgery increase costs
2. More Surgical Sites: Increased number of implants means more surgical sites
3. Potentially More Complex Surgery: May require additional surgical procedures in some cases
4. Hygiene Challenges: More implants can sometimes make cleaning more difficult

The Malo Bridge: Understanding the Terminology

The term “Malo Bridge” specifically refers to the prosthetic framework used in the All-on-4 technique, named after Dr. Paulo Malo who pioneered the concept.

Key Features of the Malo Bridge:

• Design Philosophy: A hybrid prosthesis that combines the rigidity of a fixed bridge with a flange similar to dentures
• Material Composition: Typically uses a titanium framework with acrylic or composite teeth and gum tissue
• Prosthetic Approach: Often follows the “Toronto Bridge” concept (also called “Hybrid Prosthesis”)
• Attachment Method: Screw-retained (not cemented), allowing for retrievability

The Malo Bridge isn’t a separate implant system but rather a specific prosthetic solution often used with the All-on-4 approach. However, similar prosthetic designs can be used with other implant configurations as well.

Material Options for the Final Prosthesis

Regardless of the implant configuration, several materials are available for the final prosthesis:

1. Acrylic with Titanium Framework (Traditional Hybrid)

• Composition: Titanium bar with acrylic teeth and gum tissue
• Advantages: Cost-effective, easy to repair, lighter weight
• Limitations: Wear over time, may need replacement every 5-8 years, can absorb odors/stains

2. Zirconia Framework with Porcelain Teeth

• Composition: Milled monolithic zirconia or zirconia frame with porcelain overlay
• Advantages: Highly durable, excellent aesthetics, better plaque resistance, longer-lasting (10+ years)
• Limitations: More expensive, heavier, more difficult to repair if damaged, may cause more wear on opposing teeth

3. PEEK (Polyether Ether Ketone) Framework

• Composition: High-performance polymer framework with composite or ceramic teeth
• Advantages: Lightweight, shock-absorbing properties, metal-free option
• Limitations: Less long-term data, not as strong as metal or zirconia

4. BioHPP (High Performance Polymer)

• Composition: Ceramic-reinforced polymer framework with composite or ceramic teeth
• Advantages: Shock-absorbing, natural feel, lighter weight than metal or zirconia
• Limitations: Newer material with less long-term clinical data

Choosing the Right Option: Key Considerations

When deciding between these systems, several factors should be considered:

1. Bone Quality and Quantity

• Limited Bone Volume: All-on-4 might be more suitable as it’s designed to work with minimal bone
• Good Bone Volume: All-on-6 provides additional support when adequate bone is available

2. Occlusal Forces and Habits

• Heavy Bite Forces or Bruxism: All-on-6 distributes forces better and provides more support
• Normal Bite Forces: All-on-4 is typically sufficient for most patients with average mastication forces

3. Anatomical Considerations

• Severe Maxillary Sinus Pneumatization: All-on-4 with tilted posterior implants may avoid sinus grafting
• Limited Vertical Space: Affects prosthetic material choice more than implant configuration

4. Financial Considerations

• Budget Constraints: All-on-4 is generally more affordable due to fewer implants
• Long-term Investment: All-on-6 may offer better longevity, potentially offsetting initial higher cost

5. International Patient Considerations

As you mentioned being an international patient potentially traveling for treatment, additional factors to consider include:

• Treatment Timeline: How many visits will be required and how long will you need to stay?
• Follow-up Protocol: How will maintenance and adjustments be handled across distances?
• Complication Management: What is the protocol if issues arise after returning home?
• Local Support: Is there a dental professional in your home country who can provide interim support?

Typical Treatment Protocol and Timeline

Regardless of the system chosen, the treatment typically follows these phases:

1. Comprehensive Evaluation: 3D imaging, clinical assessment, and treatment planning
2. Surgical Phase: Extraction of remaining teeth (if needed), implant placement, and possible immediate loading with a temporary prosthesis
3. Healing Phase: 3-6 months for osseointegration (implant-to-bone fusion)
4. Prosthetic Phase: Fabrication and delivery of the final prosthesis
5. Maintenance Phase: Regular follow-ups and professional cleanings

Comparing Long-term Outcomes

Research on long-term outcomes shows:

• All-on-4: Studies show 94-98% survival rates at 5-10 years
• All-on-6: Similar implant survival rates but potentially better prosthesis longevity due to better force distribution
• Material Longevity: Zirconia prostheses typically outlast acrylic hybrids by several years

My Professional Recommendation

Based on your description, I would recommend considering:

1. If bone quality and quantity are good and budget allows: An All-on-6 configuration with a zirconia framework would offer the best long-term outcome with excellent aesthetics and durability at age 58.

2. If bone is limited or budget is a primary concern: The traditional All-on-4 with a high-quality hybrid prosthesis provides an excellent balance of function, aesthetics, and value.

3. For a middle-ground approach: Consider a modified approach with 5 implants per arch (sometimes called All-on-5), which provides additional support over All-on-4 without the full cost of All-on-6.

Given your international patient status, I would also recommend:

1. Identifying a local dentist in India who can provide maintenance and emergency care
2. Ensuring your treatment provider has a clear protocol for managing international patients
3. Planning for a sufficient stay during the initial treatment phase (typically 2-3 weeks)
4. Arranging for a follow-up visit at 6-12 months for evaluation of the final prosthesis

Would you like more specific information about any particular aspect of these systems? I’m also happy to discuss the specific considerations for rehabilitation of the upper versus lower arch, as they present different challenges and considerations.

Further Reading and Resources

For more information on related topics, you might find these resources helpful:

• Dental Implants: Permanent Solution
• Full Mouth Rehabilitation: Comprehensive Guide
• Implant Materials: Titanium vs. Ceramic
• Dental Tourism: What to Consider