Two extra implants sound like an obvious upgrade, but the research comparing four and six implants under a full-arch bridge has mostly found similar implant and bridge survival between them. The better choice for a particular person depends on how much bone they have, which jaw is being treated, and how hard they bite. That is something a 3D scan and an examination answer, rather than the name of the technique.
The same idea with a different number of supports
Both approaches replace every tooth in one jaw with a fixed bridge that only your dentist can remove. With four implants, two are placed towards the front and two further back, with the back pair tilted so they can reach solid bone while staying clear of the sinuses in the upper jaw or the nerve in the lower jaw. With six implants, two more are added, so the bridge is held at six points rather than four.
The tilting in the four-implant approach was developed so that people whose jawbone has shrunk after tooth loss could often have fixed teeth without bone grafting. Six implants need room for six, so a jaw with very little bone may be harder to treat that way without grafting first. Our detailed guide to All-on-X treatment and costs covers the four-implant approach on its own.
What the studies comparing them have found
A systematic review prepared for an international implant dentistry consensus meeting (Daudt Polido and colleagues, Clinical Oral Implants Research, 2018) found similar implant and prosthesis survival whether fewer than five or five or more implants supported a full-arch fixed bridge, in either jaw. A cohort study of 217 patients followed for 3 to 13 years after immediate full-arch treatment (Zhang and colleagues, Clinical Implant Dentistry and Related Research, 2023) also found no significant difference between four and six implants in survival or complications.
A meta-analysis of upper jaw cases (Sharaf and colleagues, Heliyon, 2024) again found no significant difference in survival or complications, but did report more bone loss around the implants in the four-implant group. Most of this research is observational, so the results describe averages and do not predict what will happen in any one mouth.
When six may be preferred
The upper jaw usually has softer bone than the lower jaw, so some clinicians prefer extra support there. Six implants also spread the biting load over more points, which can be helpful for a large arch or for someone who clenches or grinds heavily. Having more than four supports can also give some margin if one implant has a problem later, because the bridge may still be supported by the others while it is sorted out.
When four may be preferred
If the bone at the back of the jaw is thin or the sinuses sit low, four implants with tilted back fixtures may avoid a graft or sinus lift that six would require. Fewer implants also mean a shorter surgery and, in general, a lower fee. Where grafting is being discussed, our article on bone grafts and sinus lifts explains what that adds.
How the decision is made
Your dentist looks at a 3D X-ray to measure the height, width and density of the bone, considers which jaw is being treated, asks about grinding and clenching, and reviews your general health, including smoking and diabetes, both of which affect healing. Sometimes the plan is set at five implants, or the number is confirmed during surgery once the bone has been seen. The number is chosen to suit the jaw, not to fit a brand of treatment.
Looking after either one
The main long-term risk for any implant is peri-implant disease, an infection of the gum and bone around it that behaves much like gum disease around teeth. Cleaning under the bridge every day with the tools your dentist or OHT shows you, and attending regular maintenance visits, matter for both designs. The bridge itself can chip or wear and may need repair at some point even when the implants are healthy. Our implant aftercare guide describes the daily routine.
Cost differences
A bridge on six implants usually costs more than one on four because there are two more implants and their components, and sometimes grafting as well. Both are significant investments. We do not list our own fees in blog articles; a written plan is provided after a consultation, and current offers are on our current deals page. If you are still comparing full-arch implants with other ways of replacing teeth, our article on implants, bridges and dentures sets out the broader choices.
What patients ask when choosing
Are six implants stronger than four?
Six implants share the load more widely, which may suit heavy bites or softer bone. In studies comparing the two, survival has been similar, so six is not automatically the stronger choice for everyone.
Can I have teeth the same day with either?
Often, yes. A fixed provisional bridge can be attached on the day of surgery or soon after when the implants are held firmly enough. The final bridge follows once healing is complete.
Will I need a bone graft?
That depends on your scan. A bridge on four implants is often planned specifically to avoid grafting, while six implants need more bone and may need a graft first.
If you would like to know which approach suits your jaw, book a dental implant consultation at Lumi Dental in Melrose Park, where we can take a 3D scan and talk through the options. Our page on full-arch implants at Lumi explains the treatment in more detail, or get in touch through our contact page.
This article is general information and is not a substitute for individual advice. A dentist can recommend the right approach after examining you.
