Understanding 3D Printing Material Options

Benefits and compromises vary by application

Andrew Pica, BA, RG

As increasing numbers of 3D printable materials become available for dentistry, perhaps the most important consideration when a laboratory is deciding what products to fabricate additively is keeping an open line of communication with its dentist-clients. Depending on the application, 3D printing can sometimes produce a superior product, but other times it can require compromises. The standards and priorities of both the dentist and the patient must be considered when deciding the best path, and improvements in the materials continue to make 3D printing increasingly useful.

What are the applications for which printing is most useful?

We make a concerted effort to utilize printing as much as possible in our daily workflow; the most frequent applications involve models, surgical guides, complete dentures, try-ins, nightguards, and all-on-X temporary prosthetics. With digital dentures, our experience has shown that printed denture bases fit better and have a higher level of predictability in comparison to a milled base, because of the limitations with milling severe undercuts. Although we heavily consider the esthetic differences between a milled and printed base, the success that we have seen drives us to prioritize printing. A few different printed base materials offer acceptable esthetics and strength. Studies show that some printed denture base materials have equal to or higher flexural strength values compared to analog dentures. It is important to note that strength tests out of the mouth do not always reflect what happens when heat and moisture are present intraorally. It is also important to consider the ability to characterize and colorize a printed base with composite to elevate the esthetics.

Where are we with other applications, such as night guards, denture teeth, and permanent crowns?

With nightguards, there are specific materials on the market that are fully functional. This depends on the client and patient that you are servicing. Some clients prefer a softness that can only be achieved through a vacuum form method. Regarding denture teeth and permanent restorations, I am a bit more critical. Our laboratory operates heavily on evidence-based practice, especially with printing. For example, with printed denture teeth and denture base material, we avoid materials that do not have a validated workflow. Although we could use carded teeth, we find that we can still deliver that upper echelon of esthetics with a high-quality milled multilayer PMMA. When trying to achieve a synergy of production and esthetics, individual bonding of carded teeth is entirely too cumbersome. With fixed prosthodontics, esthetics is at the forefront of our prosthetically driven cases. We have not seen a printed material that compares to a traditional restoration's esthetics and overall longevity. The use of printed materials for permanent crown and bridge restorations is case dependent.

How important are following the proper protocols and instructions for use when 3D printing?

It is proven that these resins are incredibly toxic in their uncured form, so they must be handled cautiously. With so many materials available, it could be tempting to create a workflow that produces an esthetic, functional outcome but compromises the safety of the material. For example, this could involve using a specific light box or light intensity that is not validated by the manufacturer. You may achieve a result that appears acceptable to the naked eye, but micro-toxins could be leaking out of that restoration from improperly curing those printed materials. Studies show printed resins will expose the patient to a whole array of potential health issues, of course unintentionally on the technician's part. Initially, the technician's intended goal was to help give them a better life, with a functioning, beautiful smile. As new materials and technology emerge, it is imperative that the technician is trained properly and takes the necessary steps and precautions to ensure that their workflow satisfies proper fit, form, and function but ultimately results in a safe prosthetic for the patient.

Key Takeaway

Digital dentistry, in general, can appear much easier than it actually is, but printing in particular is extremely nuanced. Before you enter this world, you need to do an exorbitant amount of research to educate yourself on the mountain you are attempting to climb.

About the Author

Andrew Pica, BA, RG, is the Senior CAD/CAM Technician at Nucrown Dental Laboratory in Cedar Grove, New Jersey, and an Adjunct Lecturer at New York City College of Technology.