February 2018
Volume 14, Issue 2

Digital Dentures Are Here

Proponents say digitizing a traditionally challenging process is no longer a novelty

Jason Mazda

Removable dentures have been called the last frontier for digital dentistry. For years, the knock has been that digital dentures were lacking in terms of esthetics, comfort, and various other factors. The US denture market has been projected to exceed $3.6 billion by next year,1 but only 8% of National Association of Dental Laboratories (NADL) members fabricate even one-fifth of their dentures digitally,2 and manufacturers estimate that digital dentures only account for approximately 1% of all removables produced nationwide. For the small handful of clinicians and laboratory technicians who do offer digital dentures, however, this technology is not a novelty; it is their standard of care.

“My practice has been comfortable with digital dentures for several years,” says Thomas J. Balshi, DDS, PhD, FACP, clinical professor of implant prosthodontics at Nova Southeastern University in Fort Lauderdale, Florida, and founder/past president of Pi Dental Center in Fort Washington, Pennsylvania. “It is routine, and it will be the standard of care across the profession soon. These dentures fit the patient's anatomy, they have suction, they do not have sore spots, and patients love them. When it is possible to create a superior product in dentistry, or any type of medicine, we are obligated to provide that level of care.”

The  Current  State

Although CAD/CAM has been used for crown-and-bridge applications since before 2000 and is now the dominant fabrication method in that realm, legitimate digital options for removables were not available until approximately a decade ago. Some users were early adopters of technology; others were drawn to digital dentures primarily because of a distaste for various aspects of the analog processes.

“I really avoided removable dentures for many years,” Balshi says. “The process was time-consuming, and still, I could never completely satisfy myself or the patient—the fit being the predominant problem.”

That sentiment is echoed by Valerie Cooper, DDS, MS, a prosthodontist in Dayton, Ohio, who says she disregarded digital dentures for years because she believed they would fail to meet her high standards. She finally tried the technology in 2015 after a “disaster case” in which a patient's teeth fell off of a hybrid denture, and the patient experienced a burning sensation.

“I knew I needed a better solution,” Cooper says. “I researched digital dentures and tried them, and I have never looked back.”

Various solutions have been developed to digitize different parts of the denture process. Dental teams have options such as incorporating digital scanning, utilizing 3D-printed try-ins, milling dentures in-house, or sending records to an outsourcing center for production.

“We have different protocols for each one,” says BJ Kowalski, president of ROE Dental Laboratory, headquartered in Independence, Ohio. “We tend to use an outsourced milling solution for retreads of hybrid implant-supported dentures and a different outsourced option for simple single dentures. When we fabricate a digital denture based on a more complicated case, such as one involving a surgical guide with an immediate-load prosthetic, we use our own in-house protocol.”

The common threads among these options include increased levels of efficiency and precision. Virtually all digital denture solutions also result in a permanent record, which saves significant amounts of time if a replacement or backup is needed. Several of the solutions utilize digital scanning and/or 3D printing to consolidate the record-taking process into fewer visits, which benefits both the clinician and the patient with time savings and cost savings.

“The traditional method requires a minimum of five visits because of the need to take preliminary records and casts, forecast, make custom trays, create a wax rim, record the vertical dimension of occlusion, measure the midline and the contours of the lips, and then obtain at least one wax try-in,” Balshi says. “With a digital system, it can be done in two visits. All of the records can be taken during the first visit, and if they are accurate, the clinician can review a digital version and then deliver the final prosthesis at the next visit. The fabrication time is also faster because it is no longer necessary to spend all of that time making a prosthesis by hand, including positioning the teeth in wax, which is especially important because there are fewer highly skilled and trained denture technicians available today.”

As an added advantage, the fit that results from digitizing part or all of the process leads to such strong denture retention that clinicians often need to provide patients with tips for removing them. In addition to the precision of digital technology, the efficiency of the process also minimizes polymerization shrinkage—or eliminates it, as in the case of monolithic fully milled dentures.

“Being chairside and seeing patients struggle to remove their dentures is great,” says Andre Theberge, RDT, CDT, laboratory manager for Drake Precision Dental Laboratory in Charlotte, North Carolina.

One of the most popular systems is AvaDent Digital Dental Solutions. AvaDent began milling denture bases nearly a decade ago and has continuously improved its offering since then. The company has opened its system to various different types of clinical record-taking, including the traditional measurements used for conventional dentures (ie, preliminary impression, final impression, bite rim), so dentists have the option to use their existing in-office workflow without changes. In addition, AvaDent now offers various solutions for implants such as overdentures, hybrid prosthetics, AccelerSet final prostheses (titanium/ceramic/PMMA), and surgical guides.

“We have expanded the product portfolio to go beyond just flat dentures for edentulous patients,” says Jan Slor, AvaDent's executive vice president and general manager.

AvaDent also has improved its flagship offering by developing a monolithic denture milled from a custom puck that incorporates both gingival and tooth colors. Because no bonding of individual denture teeth is necessary, Slor says the denture is 8 to 10 times stronger than conventional ones. Balshi notes that at his practice, in 300 cases of immediate loading, only one patient had a small chip on one edge of a cusp tip, and otherwise, there were no fractures, failures, or instances of the teeth popping off of the conversion prosthesis or final metal hybrid prosthesis—a well-known complication. The lack of porosity also helps keep bacteria out and avoid denture odors.

“Before this monolithic material was available, digital dentures were just conventional denture teeth bonded into a milled denture base. To me, that was only halfway there,” says Guillermo J. Molina, DDS, a prosthodontist in Ridgewood, New Jersey. “We had all the benefits of a milled base—strength, fit, retention, and comfort—but the weak link was always the bonded teeth. Now, the weak link has been removed. During the past year and a half, none of my digital dentures have fractured.”

A partnership with Dentsply Sirona has further improved that offering, as AvaDent's monolithic denture now includes the same material used for Dentsply Sirona's Portrait IPN Denture Teeth.

“They're now able to make high-quality monolithic dentures with teeth that look the same as high-quality denture teeth,” says Charles Goodacre, DDS, MSD, a distinguished professor at Loma Linda University's School of Dentistry whose desire to create a high-quality denture more efficiently motivated him to work closely with AvaDent in the early years. “Dentists and laboratories can save a significant amount of money by not stocking denture teeth.”

Another popular system is Kulzer's Pala Digital Dentures, which utilizes custom trays, digital design, and 3D-printed try-ins to decrease chair time and increase accuracy. For the final denture, Kulzer offers its proprietary injection process as an outsourcing option, or a laboratory can handle the fabrication.

“This is a digital denture that will accommodate your process, your workflow, and your technicians, within your business model, however you see fit,” says Lesley Melvin, Kulzer's director of marketing and product management.

Mark Williamson, CDT, senior technical manager, removable and implants, for Ottawa Dental Laboratory in Illinois, says that for one case, he fabricated a traditional wax denture setup along with a digitally designed, 3D-printed try-in, and the patient chose the latter.

“I pride myself on the skills I have acquired during my 36 years as a denture technician, but the digital denture blew everything away,” Williamson says.

Over the past few years, Kulzer has increased the options it offers for tooth setups, processing, try-ins, and more. A new patent pending tooth cutting mechanism will accurately aid laboratory technicians in correct tooth reduction, allowing the teeth to fit any denture base desired, including a wax try-in or an injected, printed, poured, or milled base. This is something unique that our digital denture solution will provide, Melvin says.

Newer players in the digital dentures market include Amann Girrbach (Ceramill Full Denture System), Merz Dental (Baltic Denture System), and Ivoclar Vivadent, among others. The Ivoclar Digital Denture System is a completely laboratory-controlled solution, says George W. Tysowsky, DDS, MPH, the company's senior vice president of technology.

“You still need good clinical information to ensure good esthetics, fit, and function,” Tysowsky says. “These start with a good impression, jaw relation, correct occlusal plane, and esthetic guidelines, to name a few. The Ivoclar Digital Denture System includes some innovative clinical tools that can be utilized in the digital workflow to help ensure quality results.”

Various other partial solutions exist, including software and 3D printing for specific stages of the process.

“Because dentists and laboratories have so many options regarding how much, if any, of their workflow changes, I cannot think of any reason not to utilize digital dentures,” Molina says. “The common theme is that the end product is better, and that is what our goal should always be.”

Challenges  to  Adoption

Despite the various options for integrating digitization into the denture workflow, the fact remains that the overwhelming majority of dentists and laboratories are not yet utilizing this technology. According to manufacturers and users, one of the biggest hurdles is a general lack of awareness of how advanced the technology has become.

“There is hesitation regarding the clinical precision and the esthetics of some of the materials, such as the monolithic puck, but the digital dentures that were made a few years ago look nothing like what is being made now,” Cooper says. “I would encourage dentists who have not looked closely at a digital denture recently to look again. The progress that has been made is incredible.”

Slor believes that educating patients about the benefits of digital dentures will drive more dentists to adopt and utilize the technology.

“Everything should be about the patient,” Slor says. “What do we do as an industry to inform the patient about the huge benefits of this new product? We are accustomed to doing that through the dentist or the laboratory, but as an industry, we should work directly with patients to inform them.”

Resistance to change is another issue. While some digital denture proponents detested the traditional process, opponents are reluctant to fix something they do not believe is broken.

“Adoption will require dentists who want to change the way that they have been doing things for years,” Goodacre says. “That is the single most difficult thing to do.”

Finding a laboratory to partner with for digital dentures can present another challenge. Many dental technicians have been reluctant based on concerns that the automation will make the laboratory obsolete.

“Maybe it is a scary thing,” says Williamson, who estimates from social media that 50% to 60% of his laboratory colleagues are against digital dentures. “Nevertheless, dentists will always need trained technicians who understand tooth morphology, occlusion, anatomy, etc.”

For digital dentures to become more enticing to more dentists and laboratories, some say that the cost needs to decrease a bit; however, more factors are involved than the simple cost of production.

“A dentist can make up that expense very easily on the back end because the number of adjustments needed is greatly diminished,” Molina says.

Inventory expenses do exist, however, with systems that involve in-office or in-laboratory production. Additionally, those systems require capital investment that can be cost-prohibitive.

Some systems also require the use of specific scanning techniques, which can present a learning curve for the dentist. If the design and/or fabrication takes place in the office or the laboratory, that can require an adjustment period as well.

Although some dentists say esthetics are already optimal, Kowalski says a trained technician still can discern the difference between a digital denture and one fabricated by a high-end removables technician using analog methods.

“Milled dentures are clearly superior to printed prosthetics at this point, but both materials are still are being improved in terms of esthetics,” he says.

Turnaround times are not necessarily a problem, but digital dentures generally still take longer to produce than fixed restorations, many of which can be completed in 24 hours or less.

“We can further improve the efficiency of the process as we combine printing and milling and continue to improve the technology,” Slor says.

Collaboration  Is  Key

Of course, some of the challenges involved with digital dentures are not exclusive to that segment of dentistry. Just as chairside record-taking and collaboration with the laboratory are critical in the fixed restoration arena, the same goes for digital dentures.

“The dentist still needs a good knowledge of analog skills,” Theberge says. “Some clinicians mistakenly believe that digitization eliminates the need to understand the fundamentals of dentures. While we are supplanting some conventional steps with digital steps, it is important to know why we are doing it. Why are we using templates instead of a bite block? Where are the incisal edge and the midline? Where does everything need to be positioned and how? Dentists cannot consider digital to be a panacea.”

Williamson notes that even as the software improves, outcomes will not improve unless the information being input is accurate.

“Collaboration between the dentist and laboratory is essential to get the correct information for this new technology,” Williamson says.

Education will be important. Cooper is developing courses focusing on digital dentures, and she also lectured at Inside Dental Technology's 2017 International Digital Denture Symposium (IDDS), which drew 400 attendees with a 50/50 split of dentists and technicians (See “IDDS Heads West for 2018”).

Laboratories are expected to shoulder more of that burden in part because the majority of them already have a CAD/CAM system, whereas estimates have placed the number of dentists using CAD/CAM at below 20%. Balshi believes that digital dentures will strengthen the relationship between clinicians and the laboratory and is committed to teaching digital denture treatment procedures, both implant- supported and removable, to his prosthodontic residents.

"For digital dentures to become the standard of care across the profession, laboratories need to become educated about this technology, and they need to pass that along to clinicians,” says Brian Fritsch, senior product manager, digital denture technologies, for Dentsply Sirona. “There is a common language that the two need to learn how to speak. For digital natives, it will be fairly easy, so this adoption could move very quickly.”

The  Best  Is  Yet  to  Come

The growth of digital dentures is likely to be accelerated by further technological developments. The consensus among presenters and manufacturers at the 2017 IDDS was that 3D printing will eventually revolutionize the process.

AvaDent is also the North American distributor for NextDent and is one of multiple companies planning to introduce new printable materials this month at the Chicago Dental Society's 2018 Midwinter Meeting.

“We have new microfilled hybrid tooth materials that will be offered in seven shades, and the properties are amazing,” Slor says. “We also expect four new shades of printable denture base materials that have already been cleared by the US Food and Drug Administration and look fabulous. It is now possible to print a denture base, print teeth, and bond them together—all very efficiently and with excellent esthetics.”

The evolution of digital imaging equipment could lead to significant breakthroughs as well.

“When a manufacturer develops a way for clinicians to take a digital impression and establish the vertical dimension of occlusion and plane of occlusion without the intermediary step of an analog impression, that will blow it wide open,” Theberge says. “It will need to be a combination of cone-beam computed tomography (CBCT) technology and intraoral impression scanning. Even with clear bite blocks, as soon as you displace soft tissue with any kind of instrumentation, the fit of the denture is compromised. Someone needs to figure out how to use CBCT to get the upper and lower jaw in position for the measurements required by the design software. That is our holy grail, and it will move digital dentures like zirconia moved the fixed side.”

In addition to material and technology developments, various manufacturers are expected to continue to offer more implant and hybrid solutions as well.

“An expansion of options to cover all types of prostheses being made for patients is inevitable,” Goodacre says. “It will be possible to make a removable partial denture with a totally digital process at some point, which will change the way we think about those restorations, including the laboratory procedures and the way they are taught in schools.”

As manufacturers expand their offerings, they expect users to also take an active role in the optimization of the technology.

“Once they have full control of the design and fabrication of the digital denture, the next development may come from the laboratory,” Tysowsky says.

One result of the entire evolution of digital dentures could be the expansion of the removables market in general. Cooper, for example, speculates that Medicaid patients and underprivileged countries could be among the biggest beneficiaries of a cost-efficient digital solution.

“In areas where patients do not have access to conventionally fabricated, beautiful custom dentures, this process could become popular in a very short amount of time,” Cooper says. “That might be the market that is most primed to embrace digital dentures. The issue with the high-end denture market is that there is little incentive to change something that is currently working, but there are other denture markets in which the status quo is not working.”

Kowalski echoes that sentiment, noting that digital processes can make reasonably high-quality work more affordable.

“We provide a high-end denture service,” he says, “but most of the denture market needs that service to be more economical. Patients with more money tend to prefer full-arch implant restorations or crown and bridge. Digital processes can help us provide a very good denture at a very economical price.”

As cost, ease of use, technological limitations, and other hurdles continue to dissipate, there is no doubt among those who currently utilize digital denture technology that it will become the standard of care sooner than later. Balshi says the next generation of prosthodontic residents has already embraced digital dentures and made them their standard of care.

“They see the advantages for themselves and for the patient,” he says. “It is the future of prosthodontics. It is currently being taught in dental schools in the United States and Europe, so young dentists will not be using traditional denture techniques any longer. Digital dentures are the superior method of patient care.”

References

1. Hughes K. Moving the Denture Industry Forward. Inside Dental Technology. 2013;4(8):25-27.

2. NADL 2017 Materials & Equipment Survey. Valmont Research. 2017.

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