Decision guide
All-on-4 vs All-on-6 — What Actually Decides It
All-on-4vsAll-on-6
Four implants or six under a fixed arch? The answer is bone density and arch position, not marketing. The engineering, failure math, and cost delta.
Somewhere in Miami right now, one clinic is quoting a patient All-on-4 and another is quoting the identical mouth All-on-6, and both are calling their number the standard of care. Here’s what actually separates them — and why the right answer lives in your CT scan, not in either brochure.
The engineering in one paragraph
A fixed full-arch prosthesis is a bridge, and implants are its pilings. Four pilings work when the ground is granite: the classic All-on-4 tilts the back two implants to anchor in the dense anterior bone, achieving stability that softer, graft-hungry posterior bone can’t offer. Six pilings matter when the ground is sand — typically the upper jaw, where bone density drops a full grade — spreading chewing load across more anchors and shortening the unsupported spans at the back of the arch where fractures start.
The failure-tolerance math
Implant survival runs 95–98% — but with four fixtures, each one is 25% of your foundation. A single failure usually means removing the arch and going back to a removable temporary for months. With six, one failure leaves a five-implant arch that mostly keeps working while the site heals. That redundancy is the honest argument for six, and it’s why many Miami surgeons default to it specifically in the upper jaw while happily running four in the lower.
The money translation
The delta is roughly $3,000–$5,000 per arch — two more fixtures and their componentry. Against a $22,000–$35,000 procedure, that’s a 12–18% premium for insurance against the worst-case month-three scenario. Cheap if your bone is marginal; arguably wasted if your mandible is dense enough to blunt drills.
How to use this in a consult
Don’t ask “should I get four or six?” Ask: “show me on my scan why this count, here.” A surgeon who walks you through bone density readings and arch-span math is planning your case. One who quotes the same count to every mouth is selling a package — and now you can tell the difference in one sentence.
The questions that decide it
Is All-on-6 always safer than All-on-4?
No — it's situational. In a dense lower jaw, four well-placed fixtures carry an arch with decades of published success, and two more add cost without changing outcomes. In softer upper-jaw bone, the fifth and sixth implants spread load and add redundancy that genuinely matters. The scan decides, not the brochure.
What happens if one implant fails under each system?
This is the real difference. Lose one of four and the arch usually must come off while the site heals — weeks back in a temporary. Lose one of six and the prosthesis typically stays functional on the remaining five while the site is repaired. Six buys failure tolerance; whether that's worth $3,000–$5,000 depends on your bone quality and risk factors.
Why does All-on-4 avoid bone grafting?
The rear implants are tilted up to 45 degrees, anchoring in the dense bone toward the front of the jaw and skipping the areas that usually need grafts or sinus lifts. That tilt is the entire innovation — it converted many 'no bone' patients into same-day candidates.
Which one is Teeth in a Day?
Either. Same-day loading depends on the implants reaching sufficient insertion torque at surgery, not on the count. Four that lock in tight beat six that don't; your surgeon measures this on the table and makes the call.
What should I ask the surgeon proposing either?
Show me the count decision on my CBCT. What torque threshold do you require before same-day loading? What happens — mechanically and financially — if a fixture fails at month three? A surgeon fluent in those answers has done this enough times to have opinions; that fluency is what you're hiring.