All-on-four is a dental implant technique specific to people missing all of their teeth and who want to avoid dentures. Many patients that see me in Burbank ask me about “All on Four.” Sometimes they call it “All Over Four.” The all-on-four implant procedure has few advantages, but several disadvantages.
All-on-(or over) four is intended to replace all of your teeth on one arch with only four implants. [It was popularized by an implant company, Nobel Biocare, that I once taught local Burbank courses for.]
That means that twelve to fourteen teeth are supported by only four implants. The dental implants in the back of the mouth are purposely placed at a tilted angle to get implants farther towards the back.
Personally, I have surgically placed and made teeth for thousands of dental implants including the all-on-four type.
The biggest advantage, hands down is cost. The price to do all-on-four is much less than traditional implants that are placed straight up and down in your jaw (not tilted). Typically the MINIMUM number for FIXED dental implants in the lower jaw is five and the upper jaw is six. These would be minimum numbers and would apply if your jaw is small, v-shaped, and you only want a few back teeth. Additionally, some types of bone grafts can be avoided if you have all-on-four dental implants.
Bone grafting can be avoided by purposely tilting the implants away from the sinus (avoid sinus bone grafts) and away from the lower back area where there is a nerve.
Here are two cases I did about 7 years ago:
The biggest disadvantage to the all-on-four dental implant bridge is that it is UNDER-ENGINEERED. Our natural teeth were created with multiple roots per tooth. This gives a lot of support for our strong bites. This procedure only gives you four roots!
If you were building your house right now, would you only use four beams to hold up the entire house?
I doubt it! You would want the foundation to be strong! What if one of the beams was attacked by termites (gum disease) and you had to remove it? If you only had four implants you would lose the whole bridge and have to redo it from scratch. If one of the angulated implants is the one that fails, it is going to destroy a lot of bone when I have to remove it. It will hold in the short term, but in a few years, it may have problems, and there are few qualified dental implant specialists in Burbank who can remedy the situation.
The other problem with most all-on-four fixed dental implant bridges is the fact that most dentists give you a bridge with plastic denture teeth as a final bridge! It is really just a fixed denture made of plastic with teeth that commonly break off, stain, and need to be replaced every few years. This will cost more in the long term. The rear implants can be in a bad position making your palate feel like it has a big lump on both sides.
My suggestion is that fixed dental implant bridges are made of porcelain. Please read this post to learn why this is important. When I do all-on-four, I make porcelain bridges instead, which are much less problematic than hybrid denture types.
All-on-four in my opinion should be used 1-3% of the time and is probably more of a marketing fad than solid, predictable treatment plans that involve a few more implants. I am not opposed to tilted implants. I am only opposed to using an absolute minimum number of implants. It is like jumping out of an airplane without a backup parachute.
If you are in need of full mouth dental implants, consider this a last resort. Although, cost is important, keep in mind you are pricing out body parts.
Ramsey A. Amin, D.D.S.
Diplomate of the American Board of Oral Implantology/Implant Dentistry
Fellow-American Academy of Implant Dentistry