Knowledge and Skills Remain Key
New technologies offer strength and efficiency that could soon be standard
Oscar Galvis, CDT, MDT, MS
At the hands of a skilled technician, a number of digital technologies can help make denture production more efficient now than ever. Scanning existing dentures helps eliminate the traditional custom tray and occlusal rim appointments, whether for a copy denture or simply to capture the intaglio surface and vertical dimension of occlusion. Milling can produce a strong, esthetic denture and is especially beneficial for a laboratory that already owns milling machines and does not produce a high volume of dentures. For those laboratories producing at a higher volume, 3D printing has always offered efficiency benefits, and that technology now can also produce strength and esthetics.
What is the impact of the accuracy/precision factor?
The process of creating an analog denture should be a very precise one, but it requires significant attention to detail. From setting teeth to processing an analog denture, there are numerous occasions where errors can be made. Even after following proper protocol, dentures should be returned to the articulator in order to correct processing errors and perform selective grinding. With digital denture assembly, assuming the denture design was accurate and the digital files were manufactured correctly, the only possible processing errors occur if the denture teeth are not luted correctly into the base. Digital processes result in more accurate occlusion, shorter fabrication and finishing times, and an overall less labor-intensive set of protocols. Fewer checkpoints are required; you simply fabricate, fine-tune esthetics, assemble the parts, and finish in a fraction of the time in comparison to analog techniques. That is one of the critical ways in which digital dentures are so efficient. Milling and 3D printing dentures are becoming common practice, although milling seems to still have an esthetic advantage. 3D printing offers the upper hand when fabricating more difficult geometries such as intaglio surfaces with deep undercuts.
How much of the artistry of printed dentures lies in the digital design vs post-processing?
Our laboratory mills esthetic multilayered PMMA for denture teeth and 3D prints the denture bases, which has proven to provide superior retention/fit in comparison to milled bases. In my opinion, two things make a case look natural: the individualization of teeth, and gingival margins. For the teeth, the artistry is definitely in post-processing; even with a C-clamp and 90° milling, I still want to refine the esthetics by hand at the bench. For the gingival margins, I want to mimic nature as closely as possible, which means beginning with a good gingival margin design that translates to the denture base as printed. I want the teeth to emerge from the sockets so that it looks as if they are growing from natural tissue. Beyond those factors, some dentists want to see fibers on the denture base because most 3D printed denture bases look a bit flat without them. For those dentists, I will use colors, paints, and composites to make the gingiva come to life. The key is to not spend so much time that you are negating the efficiency advantages of the technology.
Where are printed dentures now in terms of strength?
Prioritizing the flexural properties of the resins, rather than tensile strength or hardness, is paramount. The flexural properties allow 3D printed resins to shine in the arena of fracture resistance. Currently, there are 3D denture base/teeth resins that are already validated as high impact. Not only do these resins perform similarly to traditional high-impact acrylics, but some even amplify their material properties when in the intraoral environment. This means that these resins are proving to be even stronger than many traditional analog materials when in use. As a result, not only are 3D printed dentures a more viable option than they were in previous years, but they will soon be the standard that dentists and patients will expect. With the ability to increase production and quality, while reducing labor and overhead, printing will be the way of the future for removables. Remaining competitive in the future with even more advancements in 3D printing will prove difficult for anyone not adopting this technology in their laboratory.
Key Takeaway
If you are doing it correctly, implementing digital denture processes will be a journey. You still need to understand the fundamentals, and from an esthetic perspective, I definitely believe skilled hands at the bench are a requirement to produce high-end work.
About the Author
Oscar Galvis, CDT, MDT, MS, is owner of NuCrown Dental Laboratory in Cedar Grove, New Jersey, and an Adjunct Lecturer at New York City College of Technology.
