Print Resins Continue to Evolve
Factors to consider when purchasing and using additive materials
Christian Brenes Vega, DDS
3D printing has impacted every area of clinical dentistry since it became an affordable technology for most dental laboratories and dental practices. The changes in workflows over the course of just a few years for wax-ups, implant surgeries, orthodontic aligners, maxillofacial surgeries, dentures, occlusal guards, crown lengthening, and more have been mind-blowing. Current 3D printing applications—mainly in prosthetic, orthodontic, and implant dentistry—allow clinicians and technicians to be more efficient and more predictable. Developments continue to move quickly, and the future is very promising, not only for hardware and technologies but also for the evolution of materials.
Developments in 3D printing materials: The most impactful developments in 3D printing materials have been the new formulations of biocompatible resins that allow for the manufacturing of final prosthetic devices such as dentures, occlusal guards, and even crowns.
We still need more research and data to see how printing materials compare to milled or traditional materials in the long term, but many dental professionals are reporting short-term success, especially with temporary restorations. Furthermore, some facilities such as ours at Medical University of South Carolina have access to new technologies for printing titanium and chrome cobalt for different prosthetic applications, along with advances in the medical field with printed cell scaffolds and grafts.
What to pay close attention to when purchasing print materials: The additive technologies used most in dentistry utilize liquid resins.
The first thing to consider is resin compatibility; many available resins are not compatible with all 3D printers. Resin profiles should be part of the 3D printing CAM software; every resin has different parameters to be printed successfully and avoid failures or distortion. Another consideration is wavelength compatibility; 3D printed resins are usually cured either at 385 nm or 405 nm, and not all printers have dual-wavelength capabilities. Depending on the clinical application, factors such as flexural strength, stain resistance, modulus of elasticity, and wear might be important, but there is a lack of objective research comparing different resins to conclude which ones are working better; our team at the university is focused on generating data at this point that can help us understand material properties. Another important consideration is post-curing; following systematic processes and manufacturing recommendations is imperative to achieve the best results, as 3D printing resins are very technique-sensitive and we tend to oversimplify the 3D printing process to just creating a solid object from the printer.
How to get the most out of materials: Following manufacturers' recommendations for the entire process is crucial for achieving the best result; the main problem professionals face when using non-dental 3D printers is the infinite number of combinations and factors to consider for creating resin profiles on their own for dental resins.
Unless one understands how to calibrate resins and how to work with printing parameters, attempting to do this could lead to errors and printing issues. Dental 3D printing companies invest significant time and resources in developing the best printing workflows to facilitate the process for dental professionals and staff, so they can focus their time on what they do best: dentistry. We have recently found in a series of research projects (some of them pending publication) that the accuracy and texture of 3D printed models can be completely dependent upon the 3D printer and resin combinations; the same printer using a different resin can show very different results.
What's next: New formulations are allowing for improved material properties depending on the clinical applications. Stronger, biocompatible resins and ceramic particle infiltrations are allowing 3D printing resins to be used for final restorations for the first time. The possibility of printing zirconia for dental applications has also been discussed along with in vivo cellular printing. With more research and development, the future is bright.
About the Author
Christian Brenes Vega, DDS, is a prosthodontist and Associate Professor at the Medical University of South Carolina's College of Dental Medicine.