[HỎI ĐÁP BÁC SĨ]: All-on-4 or All-on-6 for a Completely Edentulous Lower Jaw—Is Six Actually Stronger?

Emily Hoang, 56, has lost all of her lower teeth and is comparing All-on-4 with All-on-6. Both approaches can provide predictable fixed full-arch rehabilitation in the mandible when correctly planned. Six implants can offer additional support and redundancy in selected patients, but current evidence does not show that All-on-6 is automatically more durable than a properly designed All-on-4. The decision should be based on mandibular bone distribution, implant positions, cantilever length, bite force, opposing dentition, bruxism, hygiene access and the final prosthetic design.

Emily Hoang, 56 – United States

Condition: Completely edentulous lower jaw and considering a fixed full-arch Implant restoration. Emily has been advised about All-on-4 in the U.S. but is wondering whether All-on-6 would provide a stronger and more durable foundation.

“My dentist in the US mentioned All-on-4, but I've read that All-on-6 might be sturdier for the lower jaw. Which one would you recommend for someone who has lost all her lower teeth?”

Hello Emily. If you have already lost all of your lower teeth, both All-on-4 and All-on-6 can be legitimate ways to support a fixed lower full-arch prosthesis.

I would not recommend All-on-6 automatically just because six implants sounds stronger than four.

For the completely edentulous mandible, four appropriately positioned implants already have substantial clinical evidence supporting a fixed complete-arch restoration. The International Team for Implantology recommends a minimum of four appropriately distributed implants to support a one-piece fixed full-arch prosthesis.

That word “distributed” is extremely important.

Four implants in excellent positions, with a wide anterior-posterior spread, good primary stability, an accurately fitting framework and a controlled posterior cantilever may form a better biomechanical system than six implants placed too close together or in unfavorable bone.

On the other hand, if your lower jaw has six genuinely useful Implant sites and the additional two implants improve the distribution of support without requiring unnecessary surgery, All-on-6 can offer worthwhile advantages.

So my recommendation would not begin with “four versus six.” It would begin with your CBCT and the design of the teeth we are trying to build.

For a completely edentulous lower jaw	All-on-4	All-on-6
Number of support points	Four strategically distributed implants.	Six strategically distributed implants.
Can it predictably support a fixed mandibular arch?	Yes, when the four implants are appropriately positioned and the prosthesis is correctly designed.	Yes, when six favorable Implant sites are available.
Potential mechanical advantage	Efficient use of available bone with fewer implants and potentially less surgery.	Additional support points may shorten the span between implants, reduce cantilever demands and provide greater redundancy in selected cases.
Does it automatically last longer?	No treatment is automatically less durable simply because it uses four implants.	No. Current comparative evidence does not demonstrate that six implants universally produce better Implant survival than four.
Bone requirement	Requires four useful sites with sufficient distribution and stability.	Requires six useful sites. Additional implants are only beneficial if the extra positions are anatomically and prosthetically favorable.
Hygiene	Four Implant/abutment sites must be cleaned beneath the bridge.	Two additional Implant/abutment sites create additional areas that must remain accessible for daily hygiene.

The evidence is particularly useful when answering your concern that All-on-6 must be “sturdier.”

A large 2025 comparative study evaluated 943 patients receiving nearly 6,000 implants supporting immediately loaded four- or six-Implant fixed complete-arch restorations.

The four- and six-Implant groups had very similar Implant survival.

At five years, overall survival was approximately 98.8% for the four-Implant restorations and 98.7% for the six-Implant restorations. When the lower jaw was analyzed specifically, the five-year figures were approximately 98.6% versus 99.4%, and that difference was not statistically significant.

This does not prove that the two treatments are identical in every mechanical respect.

The study evaluated Implant survival and did not establish that prosthetic complications, framework behavior, maintenance requirements or every individual biomechanical scenario are identical.

What it does tell us is that “six implants must survive better than four” is too simplistic.

Earlier systematic reviews and long-term mandibular All-on-4 studies also support four Implant fixtures as a well-established foundation for a fixed lower arch when case selection and prosthetic execution are appropriate.

Therefore, if your U.S. dentist has suggested All-on-4, I would not interpret that recommendation as a compromise simply because fewer implants are being used.

The next issue is the anatomy of your lower jaw.

The mandible is quite different from the upper jaw.

In many completely edentulous lower jaws, useful bone remains in the anterior region between the right and left mental foramina. Posteriorly, Implant placement may be constrained by the inferior alveolar nerve.

With an All-on-4 design, the posterior implants can sometimes be angled strategically to increase the anterior-posterior spread of support while remaining anterior to important nerve anatomy.

The goal is not to tilt implants simply because the treatment is branded All-on-4.

The goal is to position each Implant according to the available bone and the planned prosthesis.

If your CBCT shows substantial bone posteriorly and two additional implants can be positioned safely without compromising the inferior alveolar nerve or creating unfavorable restorative positions, an All-on-6 design becomes more attractive.

CBCT finding	How it influences my recommendation
Four strong Implant sites create a wide anterior-posterior distribution	All-on-4 may already provide an appropriate foundation without adding two implants simply for reassurance.
Six good sites are available and the extra posterior implants meaningfully widen support	All-on-6 may provide a useful biomechanical advantage and additional redundancy.
The fifth and sixth Implant sites are close to the inferior alveolar nerve	I would not take additional neurological or surgical risk merely to achieve the number six.
Additional implants would require substantial bone reconstruction while four favorable sites already exist	All-on-4 may be the more balanced and less invasive treatment.
Severe mandibular resorption limits both four- and six-Implant positions	The case requires more detailed reconstructive planning rather than simply selecting a package based on Implant count.

The length of the posterior cantilever is another major consideration.

A full-arch bridge normally extends posteriorly beyond the most distal Implant to replace molar or premolar teeth.

That extension is called the cantilever.

The longer the cantilever, the greater the bending forces that can act on the prosthesis and Implant system during chewing.

If two additional implants allow the most posterior support to move farther back and substantially shorten that cantilever, All-on-6 can provide a meaningful mechanical benefit.

But simply placing two extra implants between the existing four without actually improving the support geometry may provide much less benefit than the number “six” suggests.

This is why I evaluate the anterior-posterior spread, not just the number of titanium fixtures on the treatment plan.

Your opposing upper arch also matters.

If you wear a conventional upper complete denture, the loading environment is very different from a patient who has a full set of natural upper teeth or a fixed upper Implant bridge.

A natural or fixed Implant-supported opposing arch can generate substantial bite force.

If you have a powerful bite, a wide mandibular arch, parafunctional loading or a history of bruxism, I would look more carefully at whether six favorable Implant positions could improve force distribution.

Even then, six implants do not make bruxism harmless.

The framework, occlusal design, cantilever and possibly a protective night guard remain important.

Clinical factor	Why it may push the plan toward four or six implants
Excellent four-site bone distribution	Supports consideration of All-on-4 because the essential biomechanical foundation may already be present.
Six favorable sites with good posterior distribution	Makes All-on-6 more attractive if the extra sites improve support rather than simply increasing Implant count.
Long planned posterior cantilever	If additional distal implants can shorten it, six implants may have an advantage.
Strong opposing natural or Implant-supported teeth	Higher functional forces may strengthen the argument for additional support when anatomy permits.
Heavy bruxism	Requires careful force management regardless of Implant number. Six implants may provide more support in selected cases but do not eliminate the mechanical risk.
Significant posterior bone deficiency	May favor a strategically planned four-Implant solution rather than additional surgery solely to place six.
Difficulty maintaining oral hygiene	The prosthesis must be designed around cleanability. More implants create more peri-Implant surfaces that require maintenance.

There is also a reasonable argument for redundancy with All-on-6.

With an All-on-4 restoration, each Implant plays an important role in supporting the complete arch.

If one Implant develops a serious problem, the effect on the prosthesis can be substantial.

With six implants, the two additional fixtures may provide more options if a future Implant complication occurs.

But even this advantage should not be oversimplified.

If one of the most posterior implants fails and the remaining Implant positions no longer provide an appropriate anterior-posterior spread, the bridge may still need modification or redesign.

A six-Implant bridge does not automatically continue functioning normally after one Implant fails.

Redundancy is therefore a potential advantage—not an insurance policy.

At age 56, you also have a potentially long period of Implant use ahead of you.

That makes long-term serviceability important, but it does not automatically make me choose six implants.

I would be more interested in establishing a stable, maintainable design that can be professionally serviced over the next 15, 20 or more years.

That means paying attention to the Implant positions, connection system, framework, screw access, replacement-component availability and the ability to remove the bridge clinically if maintenance becomes necessary.

The final prosthesis is just as important as the Implant count.

An accurately manufactured rigid framework on four appropriately distributed implants may perform better than a poorly fitting framework on six.

Likewise, an All-on-6 restoration with an excessively bulky underside that cannot be cleaned properly is not automatically a superior treatment.

Peri-implant disease can develop around four implants or six implants when plaque accumulates and maintenance is inadequate.

This is why I would inspect the planned tissue-to-prosthesis transition and make sure you can use an interdental brush, floss threader or appropriate oral irrigator beneath the fixed bridge.

If the six Implant positions produce a cleaner and mechanically better prosthesis, that supports All-on-6.

If they make hygiene more difficult without providing meaningful additional support, simply having more implants is not a clinical advantage.

Immediate or early fixed provisional teeth are another issue that should not be confused with the choice between four and six.

Having six implants does not automatically mean that your temporary bridge can be loaded immediately.

The actual primary stability of the implants has to be assessed during surgery.

ITI guidance recommends considering systemic health, Implant stability, bone grafting, Implant dimensions and clinician experience when determining the loading protocol.

If four appropriately distributed implants achieve good primary stability, an All-on-4 provisional restoration may be considered for early loading.

If six implants are placed but several have inadequate stability, the fact that there are six does not justify forcing an immediate-loading protocol.

The loading decision follows the biology and mechanics of the actual surgery.

Because you are already completely edentulous in the lower jaw, we also have one simplification: there is no need to decide whether natural lower teeth should be extracted to create an All-on-X case.

Instead, the consultation can focus directly on the amount and distribution of mandibular bone, nerve anatomy, restorative space, bite, facial support and the prosthesis you want.

At Dr. Care, the decision between four and six implants within All-on-X full-arch implant treatment is finalized after CT Cone Beam 3D assessment and prosthetic planning rather than from Implant count alone.

If your CBCT showed four excellent sites, a favorable anterior-posterior spread, a manageable cantilever and no major bruxism, I would be comfortable recommending All-on-4 rather than adding two implants simply because you are worried that four sounds insufficient.

If the CBCT showed six favorable Implant sites, a broad arch, relatively high bite forces and a clear reduction in cantilever or span when the fifth and sixth implants are added, I would lean toward All-on-6.

That is the type of patient-specific reasoning I would use in your case.

If Emily's CBCT and bite show...	My likely direction
Four strong sites, wide support distribution, short controlled cantilever and moderate bite forces	All-on-4 may be completely appropriate. I would not place two unnecessary implants simply for psychological reassurance.
Six excellent sites and the additional posterior implants clearly shorten the cantilever	All-on-6 becomes attractive because the two additional implants are providing a real biomechanical benefit.
Strong opposing dentition or high functional demand together with six favorable sites	I would give All-on-6 stronger consideration, while still addressing the occlusion and any bruxism.
Severe posterior resorption and unfavorable fifth/sixth sites	A well-designed All-on-4 may be preferable to performing extra surgery purely to reach six implants.
Unfavorable anatomy even for four strategically distributed implants	The case requires a different reconstructive strategy rather than forcing either standard All-on-4 or All-on-6.

Cost is another difference, although I would place it after the clinical decision rather than before it.

According to Dr. Care's current dental implant price list, the Implant component of All-on-4 currently ranges from VND 109,000,000 to VND 149,000,000 per lower arch depending on the Implant system, while All-on-6 ranges from VND 158,000,000 to VND 218,000,000.

Implant system	All-on-4 / arch	All-on-6 / arch
Neodent	VND 109,000,000	VND 158,000,000
JD Dental Care or Straumann SLA	VND 129,000,000	VND 188,000,000
Nobel Active or Straumann SLActive	VND 149,000,000	VND 218,000,000

The current published prices include VAT. The definitive fixed full-arch prosthesis is priced separately.

After combining the currently listed Implant and final-prosthesis options, the complete reference range is approximately VND 139,000,000–223,000,000 per arch for All-on-4 and VND 194,000,000–297,000,000 for All-on-6.

The additional cost of All-on-6 reflects not only two extra Implant fixtures but also additional restorative components and a larger prosthetic configuration.

I would therefore not recommend spending more simply because All-on-6 sounds more reassuring.

If the additional two implants improve your actual treatment geometry, the extra cost may be clinically justified.

If they do not, a higher Implant count may simply mean more surgery, more components to maintain and a larger financial investment without a proven survival advantage.

Your final treatment would follow Dr. Care's standard clinical dental implant protocol, beginning with general-health assessment, CBCT imaging and prosthetically driven three-dimensional Implant planning.

For the lower jaw, I would specifically map the mental foramina and inferior alveolar nerve, measure available bone width and height, determine the achievable Implant distribution and digitally plan the position of the final teeth before deciding where the four or six fixtures should go.

DCARER dynamic navigation may also be considered at Dr. Care when real-time control of Implant position, angle and depth would be clinically useful.

Navigation can help the surgeon follow the digital plan around important anatomical structures, but it does not create bone and it does not make six implants inherently superior to four.

The treatment plan still comes first.

For you, Emily, if I had to give you a recommendation before seeing your CBCT, I would say this:

Do not reject the All-on-4 plan your U.S. dentist mentioned simply because you have read that All-on-6 is sturdier.

For a completely edentulous lower jaw, All-on-4 is an established fixed full-arch treatment and four appropriately distributed implants meet the international consensus minimum for a one-piece fixed complete-arch prosthesis.

I would choose All-on-6 only when your anatomy and prosthetic design show that the fifth and sixth implants add something meaningful—better posterior support, shorter cantilever, improved force distribution or useful redundancy—without requiring disproportionate additional surgery.

If your lower jaw has excellent bone for six implants and you have high functional demands, All-on-6 may ultimately be my preference.

If your lower jaw has four excellent strategic sites and the additional two positions are poor or add little biomechanical value, I would prefer a carefully executed All-on-4 over an All-on-6 performed simply because six sounds stronger.

The decision should therefore be made after comparing your CBCT with the planned prosthetic teeth, your upper opposing arch, bite force, history of grinding, hygiene ability and the amount of posterior cantilever that each design would create.

This consultation is general guidance only because I have not yet reviewed your mandibular CBCT, inferior alveolar nerve position, bone distribution, opposing upper dentition, bite force, bruxism history or restorative space. Those findings are necessary before recommending All-on-4 or All-on-6 for your specific lower jaw.

References

International Team for Implantology. Number of Implants Placed for Complete-Arch Fixed Prostheses — ITI recommends a minimum of four appropriately distributed implants for a one-piece fixed complete-arch prosthesis and advises considering the consequences of future Implant loss or complications when choosing the number of implants.
Caramês JMM, Francisco HCO, Vieira FA, et al. Four vs. Six Implant Full-Arch Restorations—A Direct Comparative Retrospective Analysis in a Large Controlled Treatment Cohort — A 2025 cohort of 943 patients found high and comparable Implant survival for four- and six-Implant fixed complete-arch restorations. Five-year mandibular Implant survival was approximately 98.6% and 99.4%, respectively, without a statistically significant difference.
Malo P, de Araújo Nobre M, Lopes A, et al. A Longitudinal Study of the Survival of All-on-4 Implants in the Mandible With up to 10 Years of Follow-up — Long-term clinical evidence supports four implants as a viable foundation for fixed complete-arch mandibular rehabilitation when appropriately planned.
Polido WD, Aghaloo T, Taylor TD, Morton D. Number of Implants Placed for Complete-Arch Fixed Prostheses: A Systematic Review and Meta-analysis — The evidence underlying ITI consensus supports individualized Implant number based on prosthetic requirements, available bone and Implant distribution rather than assuming that a higher Implant count always improves survival.
Heydecke G, Zwahlen M, Nicol A, et al. What Is the Optimal Number of Implants for Fixed Reconstructions? — Systematic-review data demonstrate high long-term survival for mandibular fixed complete-arch prostheses supported by four to six implants.
Dr. Care Implant Clinic. All-on-X Full-Arch Implant Treatment — Current Dr. Care information regarding All-on-4, All-on-6, CBCT-based treatment selection and full-arch restorative planning.
Dr. Care Implant Clinic. All-on-4 or All-on-6: Which Factors Determine the Choice? — Current Dr. Care guidance emphasizes bone quantity and distribution, anterior-posterior Implant spread, cantilever length, bite force, opposing dentition, prosthetic design, hygiene and surgical burden rather than Implant count alone.
Dr. Care Implant Clinic. Dental Implant Price List 2026 — Current All-on-4 Implant-component prices range from VND 109–149 million per arch and All-on-6 from VND 158–218 million, with definitive full-arch prostheses priced separately.
Dr. Care Implant Clinic. Standard Clinical Dental Implant Protocol — Current Dr. Care pathway covering health assessment, CBCT, Implant planning, surgery, healing and definitive restoration.

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