Like most materials used in health care, denture materials have evolved profoundly over the past 300 years or so. For centuries now, people wishing to replace all their teeth have searched widely—often in vain—for biocompatible, comfortable, aesthetically appealing, and long-lasting materials. Early dentures were more often than not embarrassing, unattractive and poorly functional replacements for natural teeth.
In the pre-industrial world, before 1800, dentures were predictably primitive. Removable oral prostheses were often covered with genuine human teeth, sometimes recovered from cadavers. Otherwise, false teeth were usually made from natural materials such as wood or animal bone. Some historical dentures were carved entirely from ivorybut they required a highly skilled and time-consuming process accessible only to the wealthy.1 While these devices could be relatively convincing, they were crudely (i.e. painfully and unreliable) held in place by springs and weights and prone to staining and wear.2
Access to dentures was finally democratized in the mid-nineteenth century when Charles Goodyear developed vulcanite, which quickly became the preferred material for dentures and held its place until the first third of the 1900s. Of course, polymethyl methacrylate (PMMA) has been the industry standard for denture base manufacturing since its introduction in the late 1930s.3 In the decades since then, while manufacturing processes have been perfected and new innovations have come and gone, PMMA has remained the most widely used denture material.
With the benefit of historical perspective, we can now look back on early devices and understand them as simple, unsanitary, and otherwise limited. In a few years, I argue that we should similarly assess the removable prosthesis from the beginning of this century.
The analog to digital evolution
In 1994, the first study of digital dentures appeared in the International Journal of Prosthodontics.4 The paper introduced a new process where the authors used a laser scanner to take denture impressions and 3D printed a tooth and a base outline, which allowed a denture to be fabricated using light-curing resin. While the ideas in the study were groundbreaking, 3D printing at the time frankly wasn’t mature enough for clinical use, so the emerging digital denture industry focused instead on CAD/CAM milling. A proof of concept detailing a technique for milling a double wax denture was published in Journal of Oral Rehabilitation in 1997.5
The first commercial digital denture was only made in 2011 — well over a decade later. Global Dental Science designed and manufactured the device, which it marketed as AvaDent digital dentures. AvaDent remains an authority on the current digital denture system market, alongside options from competitors such as Ivoclar, Dentsply Sirona, SprintRay, VITA Zahnfabrik (Vita Vionic) and Merz Dental (Baltic Denture System).6
Milled denture manufacturers developed and standardized PMMA sponges for placement in CNC mills. The first milled dentures still involved considerable technical, hands-on work, as manufacturers could only grind the base of the denture. they attached carded denture teeth to the base one by one. Over time, dental laboratories developed improved systems that allowed a complete set of teeth to be milled as a single piece. This piece would then be welded to a separately milled base and returned to the mill for finalization (Ivoclar oversize milling process). Today, the best milled denture systems make monolithic dentures. 3D printing is now playing a larger role in denture manufacturing due to its already low cost and impressive scalability. In recent years, the development of new photopolymers and sophisticated manufacturing techniques have significantly reduced the cost of entry into this exciting technology, so that it has become a viable option for job shops. Today, properly equipped laboratories can print a denture base in pink material that is then bonded to carded denture teeth or to a monolithic or segmented printed dental arch. Such systems include the Lucitone Digital Printing Denture System (Dentsply Sirona) and the SprintRay High Impact Denture Solution.
The development of proprietary digital denture design software was another ground-breaking innovation. In some cases, commercially available software systems were proprietary suites specifically designed for digital denture fabrication (eg, AvaDent Connect). Elsewhere in the industry, leading companies such as Ivoclar are using specialized 3Shape modules to extend the capabilities of pre-existing dental design software.
The various benefits of digital dentures
The tech industry favors the word “disruption” to describe paradigm-shifting changes in methodologies—and I’m guilty of using it myself. Lately, I’ve found it more productive to shift my focus away from how digital dentures are disrupting old ways of working and instead to foreground how digital dentures are actively benefiting clinicians, patients, and labs.
Many leading clinicians are already taking advantage of digital technology, which makes design and prostheses infinitely reproducible. In basic terms, modern digital dentures replace error-prone plaster casts with accurate electronic data sets, allowing adequately trained dental professionals to scan a patient’s mouth or physical impressions or casts, convert them into electronic 3D renderings, and begin an accurate CAM process with the push. of a button—all of which improve the aesthetic dimensions and fit of the denture, if the patient so desires.
Digital methods simplify many potential friction points in the reference denture workflow. The analog reference denture workflow is popular in part because it condenses clinical steps and allows clinicians to use past experience as indicators of complexity, measurably improving predictability.7 However, clinicians using conventional laboratory techniques have often been unable to accurately reproduce complex existing dentures.8 Importantly, for inexperienced clinicians, digital workflows alleviate the intimidation factor that can accompany full denture treatment in general. With traditional methodologies, a single mistake can send the clinician back to square one. This reality creates a significant fear factor. Because digital workflows perfectly preserve patient records, clinicians gain peace of mind, allowing them to do better work without trepidation.
In almost all cases, digital denture workflows require fewer and shorter appointments — including post-op visits.9, 10 While the benefits of reduced office hours should be obvious to clinicians, the potentially profound benefits of patient access should not be overlooked. Statistically, patients requiring removable full dentures are disproportionately likely to have complex medical profiles and/or difficult socioeconomic circumstances. Specifically, they are less likely to have private transportation, more likely to experience mobility issues, and less likely to live near a dental office. As a general rule, we should not take these patients’ ability to come to the office for granted.
Patients also benefit from the greater degree of precision (which means a better fit) and superior functional quality of digital dentures. According to Dr Brian J. Goodacre and Charles J. Goodacre of Loma Linda University in California, USA, more rigorous comparisons of conventional denture base materials and milled bases commonly used in digital workflows have concluded that milling produces higher bending strength and higher accuracy and truth,11–15 Allowing milled bases to respond more positively to random damage.
Overall outcomes are likely to improve further as future generations of dentists and technicians enter the workforce familiar with these new workflows. According to Wendy Auclair Clark, clinical assistant professor of prosthodontics at the University of North Carolina at Chapel Hill in the US, digital dentures are now an integral part of the full dental curriculum at top dental schools.
The digital reference denture technique
I’ve written and taught extensively elsewhere about the reference denture technique, also called the “denture duplication workflow.” In the right hands, I believe this seamless and technically and clinically complete workflow offers the highest possible standard of predictable care and precision craftsmanship.
The increasingly popular technique is ideal for edentulous patients who are generally satisfied with their existing dentures at the end of their normal lifespan. In appropriate cases, the digital reference denture workflow provides technicians with a sophisticated digital record of a patient’s existing information, allowing clinicians to restore the patient with greater confidence, predictability and accuracy than would otherwise be possible.
Using traditional methods and materials, reproducing an existing hand-crafted denture within acceptable limits – never mind perfectly – is painstaking. As I’m sure you know, the final quality of an analog denture is largely determined by the hand-eye coordination and motor dexterity of the person making it. The risks of human error are significant and unavoidable.8
