Esthetics, Function, and Efficiency
From zirconia to polymers to nanoceramics, new materials improve capabilities
Alexander Wünsche, CDT
Maximizing efficiency while maintaining quality is critical for dental laboratories today, and many of the latest millable materials on the market help accomplish that. Workflows can become more efficient as materials allow technicians to minimize processing steps. For example, we are approaching a time when we can fabricate esthetic cases with minimal to no layering. I rarely use nonshaded zirconia anymore because preshaded, multilayered zirconia allows me to eliminate an entire step; we do not even need to shade or pre-sinter a zirconia hybrid with pink anymore because such powerful porcelains are available for staining and glazing. As materials continue to evolve, we will gain the ability to achieve even better esthetics more efficiently.
How can new zirconias be optimized?
Laboratories need to be familiar with the personality of each material. With every advantage comes the need to learn how to deal with new factors. For example, higher translucency multilayer zirconia usually has a different strength factor, so we need to learn when we can use it. Design parameters also may be different. As more materials become available, learning the indications and counter-indications becomes more challenging, but it is essential.
Additionally, most of these new materials are very difficult to repair. A metal frame can be cut and soldered, but if a zirconia bridge breaks or does not fit, or a polymer bar breaks, it must be remade. This requires different approaches to cases, with the final result in mind and an awareness of exactly what you will be facing throughout the case. Communication and a team approach becomes even more essential then, as well.
What can the new high-performance or techno-polymers help you do?
Polymers can help achieve better restorations for specific patients. They do not replace current materials, but they are a fantastic add-on. Having PEKK or PEEK does not mean metal is no longer necessary; metal is still a very good material. For a patient who has enough vertical space, however, a polymer frame can provide more comfort, and it can be milled more easily in-house. Patients who have had other restorative work in the past comment that polymers are more comfortable. Regarding longevity, in approximately 7 years of polymer cases, I have not seen any failures.
Polymers also can be used in combination with other materials. For example, I can bond lithium disilicate crowns to the frame and finish with composite if I consider the exact recommended procedures.
What other impactful developments are you seeing?
The new PMMAs for digital dentures are exciting. We are getting 13-layer gradients of translucency and chroma in each blank, and they are denser and less porous, so they are really strong. I am fabricating full-arch temporaries without a reinforcement, and they are holding up. I am milling dentures with both bridges connected to the base, which is really esthetic. One thing to be careful of, however, is that the consistent gradient of these blanks does not necessarily mimic nature; the materials are getting better, but they are not there yet.
Nanoceramics are very interesting also. They can have very specific roles. I sometimes replace denture teeth with nanoceramic crowns or teeth. I like to utilize them on certain implant cases because they are more forgiving than full zirconia crowns. I also use them for younger patients who need braces still because I can bond braces on; also, the crown is easier to remove because it is softer.
A broad knowledge of current materials is crucial for laboratories to even survive now. Young dentists want to use these new materials, and they want their laboratories to know all about them.
About the Author
Alexander Wünsche, CDT, is the President of Zahntechnique in Miami, Florida.