All on x and All on 4 framework options
All on 4 framework or all on x framework choices are no longer just a choice between what kind of metal. Advances in material science now allow the use of many new materials and manufacturing techniques are also changing.
All on x or all on 4 framework options
All on x or all on 4 framework options can be broken into three general categories. The first is metal and has been around the longest, the second is porcelain, the final consists of several materials that I am grouping together.
#1 Metal all on 4 or all on x frameworks
- Gold alloy or other noble metal alloy
- Chromium Cobalt
Advantages of metal all on 4 framework
- Long history or use in dentistry and many dental labs and dentists are familiar with the product.
- Very strong and difficult to break when made properly.
- If the all on 4 metal framework breaks, we can be laser weld it back together. This is not easy and maybe impossible if there is porcelain on the metal.
Disadvantages of metal all on 4 frameworks
- Metal costs more than other frames and the noble metal frameworks in particular are far to expensive to be practical.
- Heavy and if need to have a large frame the individual may notice the weight.
#2 Porcelain all on x framework
Advantages of zirconia all on 4 framework
- It is white and is very strong.
- Zirconia is a very tissue friendly material.
- If want strong teeth that are hard to break and do not wear down then you can make the framework and teeth one piece and this cuts way down on cost.
Disadvantages of a zirconia all on x framework
- Technique sensitive so not all labs or doctors will know how to work well with it. This is mostly out of the doctors hands.
- Need to ensure using high quality zirconia
- If the lab does not treat the zirconia right or if they use an inferior zirconia product, zirconia frameworks can break and there is NO fixing it.
#3 Polymer, resin, fiberglass all on 4 framework
Of these frames there are some advantages and disadvantages of each one. For instance, Trilor and Trinia do not hold up well when we expose them so they must have composite covering them. We can expose Pekkton to the oral environment. We have an entire post that discusses the fiber reinforced framework.
- Pekkton is the strongest material in the high performance polymer family.
- Trilor is a glass fiber reinforced resin
- Trinia seems to be the same or very similar to Trilor.
- Juvora is a PEEK product and I feel the other polymer materials make more sense for frameworks.
Advantages of the polymer all on 4 framework
- They easy to mill and furthermore the milling pucks are cheaper to buy.
- All the polymers and resins are lightweight in comparison to the other categories and therefore are easy for patients to adapt to.
- They act as a shock absorber since they have some give. This is the best attribute of the material as it likely will help take some of the stress of off other important parts of the system.
- The fit is better than zirconia or titanium according to Yilmaz 2018 JPD
Disadvantages of the polymer all on x frameworks
- Can not be repaired if breaks, however, we can re-mill them cheaply.
- New product so not many labs will know the material well and there is not a lot or research behind it.
- Some must have a composite, acrylic, or porcelain coating to stop fraying, notably Trilor and Trinia.
How do we make the different all on 4 framework options?
Today nearly everyone is milling their implant frameworks but there are other ways to achieve an accurate high quality all on x framework.
Milling the all on x framework
The most common method of making all on x frameworks. We can mill a commercially pure block of material to very precise specifications. We can mill every material available today and for many materials the only way to make them is to mill them. Materials typically come in a block that we call a puck because it looks like a hockey puck. The design for the framework is made on the computer or we scan the design into the computer. This CAD/CAM technology drastically increases accuracy and decreases labor costs. s intrinsically homogeneous
3D printing the all on 4 framework
I am sure there are some places 3D printing all on 4 frameworks but it is not common. This additive manufacturing technology could replace the milling in popularity at some point but for several reasons is just not there yet. If using a metal it is currently easier to print resin or wax and then use lost wax according to Dawood.
Lost wax technique for an implant framework.
Traditionally metal was the only option and we made it the same way we made everything else in metal for dentistry. We hand create or print the framework in wax or resin and use the lost wax technique to cast it into metal. This technique can create air pockets with inconsistencies in the frame and shrinkage upon cooling. Furthermore, since frameworks are large there is more shrinkage. The larger it is the more error is built in due to cooling. The cooling of the metal results in shrinkage and misfits, which for small things like crowns is acceptable but for large volume fall on x frameworks create serious misfits. To do this right often requires sectioning and laser welding the parts back together on the model. This is labor intensive, expensive due to metal costs, and inaccurate, therefore it is rarely done today.
What is our preference for an all on x framework?
Finally, my ideal all on x prosthesis is titanium or CrCo framework with some sort of porcelain teeth on one arch and nanocomposite teeth on the other arch. This allows the teeth to be the shock absorber instead of the framework or the implants. I have instances where I prefer the polymer frameworks such as cases with little or no cantilevers, but since the products are new I worry about long term durability. Since you have an interest in framework choices you likely have an interest in tooth selection too, therefore our all on 4 teeth selection page may be of interest.