All-on-Four is a treatment modality for replacing all of the teeth in a single arch (either upper or lower). It is called All-on-Four, because all of the teeth are replaced by a fixed dental prosthesis (like a denture or a bridge) that is supported by four implants. Sounds great, right?
There is a saying in the dental world that makes light of the fact that All-on-Four can have a high rate of complications. We say, "All-on-Four, but none on three." This implies that if you try to support a full arch of teeth on four implants but you have a problem with one of the implants (or if it fails), you aren't left with enough to support any teeth. I don't like the name All-on-Four because it focuses on the number of implants, but the patients who I see usually couldn't care less about the number of implants they get, as long as they get a strong long-lasting, natural looking, functional tooth replacement. I worry about the implants because I know that any restoration requires a strong foundation, but patients mostly care about the teeth!
I have several problems with the All-on-Four treatment modality:
Four dental implants should be the minimum number of implants required to replace a full arch of teeth. There are many indications that require more implant support.
The implants are usually placed in a way that leaves a "cantilever", or a section hanging off the back that is not directly supported. Depending on your anatomy and the clinician making the denture, this cantilever can be rather lengthy, which risks fracturing the denture.
The idea that any treatment can be applied to every patient the same way. Patients are all unique. They vary in jaw anatomy, muscle function, bite force, even in the patterns their jaw follows when they chew. Why do some dentists think that using the same treatment on every patient will work? Sure it will work for some patients, maybe even most patients, but there will always be patients for which four implants are not enough.
At Smile Again, we "plan for the best but prepare for the worst" by placing a minimum of 6 implants to support the same dental prosthesis as the All-on-Four. If there is a situation where a patient needs more implants to support the teeth, then we place more implants. And of course, we don't charge anything extra for these implants. We believe in setting ourselves and our patients up for success on the first try.
Jonathan Geleris, DDS, FICOI, AFAAID
Disclaimer and disclosures: I'm a dentist who performs dental implant treatments, and general dentistry in Walnut Creek, California. I don't work for any dental companies (other than my practice). Nobody pays me to write this. As much as possible, I hope to present factual information supported by solid science, however, humans are complex, and the science in this field is constantly evolving. Some of what I present may be based on my opinion.