Interested in learning more about the all on 4 (all on four) or AO4?
All on 4 is a trademark name given to a denture permanently attached to a jaw by four implants, hence the 4 in all on four. It traditionally uses acrylic just like a denture. The options have changed a lot over the years and the number of implants is not necessarily four, but the name is catchy so it stuck. It is often seen abbreviated as AO4, which of course stands for all on 4.
What is the all on 4 and what are the different AO4 options?
All on four consists of a denture that attaches to at least four dental implants. This implant supported denture option is heavily advertised as an “All-on-4”, yet there can be more implants. In addition to all on 4, another common name for the AO4 is hybrid denture. The other options for all on 4 can be found on our implant supported dentures page.
The all on four is a very good option. AO4 is only removable by your doctor, meaning it stay in at all times. There are several significant disadvantages compared to an implant supported bridge. First of all, this option usually has less implants and therefore provides 1 or 2 less teeth on each side in the back. Additionally, if an implant ever failed and you only have 4 the whole prosthesis may not function properly anymore. Furthermore, implant supported dentures use high end denture teeth and acrylic instead of porcelain. Denture teeth and acrylic are less esthetic and much less durable. Acrylic is porous and thus impossible to really clean. This can result in unpleasant odors. On the plus side acrylic is much cheaper to repair than the above option.
What is the cost of an all on four?
A traditional all on four costs $20,000 – $23,000 per jaw in our office. This is thousands cheaper than most places offer the all on 4. We can offer at a lower fee because we have only one doctor that manages your case from start to finish and that doctor is also the owner of the business, so basically less people need to profit from it. We also do not have a large marketing budget and billboards on all the interstates, that ultimately you end up paying for. Most cases are $23,000 for the acrylic version of the all on 4. This price covers all of your per-surgical work up, the first set of AO4, and your final all on 4.
The price has a range because occasionally people need significant bone grafting or many extra implants. The are other factors that may make your case more complex that are not worth going into detail on this page about.
How can you pay for and afford the all on 4?
We will help you maximize any dental insurance benefits you may have, more on that below. Ultimately, however, most of the cost will be on you to pay out of pocket. Like most expensive things in life, financing options are available. We work with 3 different financing companies to get you the best terms and rates. The company that, in our experience, consistently offers the best rates is Lending Club.
We have a secure link here that you can go to and choose from multiple terms that meet your comfort level for paying. Filling this form out will not impact your credit score in anyway, as Lending Club does what is called a soft pull. The soft pull allows them to give you very accurate terms without having your credit history recognize that you are financing something, this is another reason we like Lending Club because so few dental financing offer a soft pull. To learn more about a soft pull click this Investopedia link.
Will your medical insurance cover your AO4?
Will your dental insurance cover your all on 4?
If you have dental insurance it will cover up the maximum that your plan allows, this is usually one or two thousand. We often spread the procedure out over two calendar years to get the extra annual benefits for you. However, even in the best case scenario your dental insurance will only cover about 25% of one AO4.
How do you get your all on four?
The steps for an AO4 are custom to your unique situation. The basics are that you come in for a consult and a 3D x-ray. We talk about your options and make a plan. It takes 6-8 weeks to prepare things for the surgery date, we are actually taking the steps to fabricate your “teeth in a day”. The day of your surgery we remove any teeth and bone that we need to and place your temporary acrylic teeth. These temporaries are very similar to the final teeth but not as durable. One or two weeks late we remove stitches and check healing. We check healing again at week 3 or 4 and again around month 2.
6 months after completing the surgery we start the 6-8 week process of making your final teeth. There are many visits to the office but most cases do not take as long as shown here. Most of the visits are very short, with the exception of the surgical dental visit.
What are the problems and maintenance issues with all on 4?
If you have an acrylic all on 4, according to Dhima it will almost certainly have problems of some sort at some time. The main issues we see are minor and involve the acrylic. Since acrylic is fairly weak we see damage in the form of teeth popping off, teeth wearing down, and acrylic breaking. The teeth popping off and acrylic wearing down can be avoided with use of a protective night guard, but given enough time these things are to be expected. Bozini shows in his 2011 study that this is common even after only 5 years of use.
If you are a grinder or clencher of your natural teeth you are likely to continue this habit and are at higher risk for problems. The costs of these issues will range from a few hundred to maybe a thousand in the worst case. To repair a broken AO4, the denture must be removed and given up for an entire day so that the lab can work on it.
Another issue that can happen is that a dental implant can fail. After the first year this is highly unlikely to happen in any given year. We usually over-engineer all on fours now to be all on 5 or more so the loss of one implant will not impact you. However, the loss of one in a critical are when there are only 4 can start a domino effect of losing more implants and eventual loss of the all on four. We have personally never seen this and it is very rare, but it can happen given enough time.
How to clean your all-on-four is on our all on 4 maintenance page.
We recommend yearly denatl visits and cleanings and x-rays every 5 years, unless there is some sort for issue or concern. The details for cleaning and maintaining is in the link on the above title.
The rest of this page is more technical information on the all on 4.
Traits that indicate high risk for all on four problems.
- Male 1
- Opposing natural dentition 1 or long term fixed implant supported full arch prosthesis 1-2
- Poor bone density 1-2
- Non-axial loading >20 degrees 2
- Nonrigid splinting 2
- Parafunction 2
- Thermal surgical injury if guided 2
Traits that indicate less risk for all on four problems.
- Systemic factors 1-2
- Local infection/pathology 1-2
- Opposing complete arch implant supported prosthesis 1
- Bone volume 1
- Smoking 1
- Bruxism 1
- Distal posterior implant site 1
- Cantilever 2
- Improper AP spread 2
- 6 or less implants 2
- Inadequate length/size implants 2
- Uncooperative patient 2
Dental research on the all on four will continue to grow as studies mature.
All on 4 is as good as an all on 6 according to Branemark 1995.
All acrylic all on four holds up as well as an all on four with a metal substructure. Crespi 2012 believes the acrylic may be beneficial to the implants as a shock absorber. That gives me further interest into using Pekk as a framework.
Double arch all on four has more complications than single arch, but survival is same according to Nobre JPD 2015.
EMG shows muscle activity same for dentate and all-on-4 but much less for denture patients according to DeRossi 2013.
Bidra 2012 lists the surgical options for gingival display all on four cases
- Ostectomy can be done with a saw or chisel for mild to moderate gingival display, but must have enough space beneath sinus and/or nasal floor.
- Lefort I was one suggestion but seems like a highly unrealistic option.
- Orthodontic intrusion is an option if just the anterior has supra-erupted.
- Plastic surgery is another great option for the right candidate and would utilize procedures like lip repositioning for hyper-mobile lip or Botox.
- Finally, one could abandon the all on four option and make an overdenture.
All on 3 research
An all on 3 works according to Oliva 2012, but this was a small study where all but 1 case was loaded conventionally. Bedrossian JOMI 2019 states all on 3 is fine but should use wider diameter implants.
The all on 3 implants seem to hold up with same percentage but the prosthesis may have more issues according to Lima JOMI 2018. Mezzari JOMI 2019 has a 5 year study on the all on 3 showing 97% success at 5 years when done in the mandible.
All on 2 and all on 1 or fixed-on-1 and fixed-on-2
This can work in the right circumstance. It is not normal treatment though and should be a last effort on a very old patient. Cannizzaro JOI 2019