Digital scanners that create intraoral impressions are taking a bite out of the conventional dental impression market. Users say that the resulting oral appliances are more patient friendly and effective and that a digital protocol may eventually become the new standard of care.
A dentist taking an intraoral impression is faced with an array of responses from patients, none of which are typically positive. Patients may gag when the goopy material is placed in their mouths, feel claustrophobic or panicky mid-impression, or even refuse to be fitted. While many sleep dentists provide only conventional manual impressions, some have begun offering their sleep apnea patients impressions via a digital scanner instead. And a new case study shows that, in addition to patient-friendliness, these intraoral scanners may actually produce superior appliances.
“The fabrication of oral sleep appliances without dental impressions is as effective and more patient-friendly than traditional methods and may become the new standard of care,” says Gregory K. Ross, DDS, a dentist in private practice in Stillwater, Minn. His poster, “Fabrication of an Oral Sleep Appliance Without Dental Impressions,” presented at the American Academy of Dental Sleep Medicine (AADSM) 23rd Annual Meeting, used digital scans of a patient’s dental arches and therapeutic bite, which were then electronically submitted to a dental lab for fabrication. The sleep appliance’s effectiveness was evaluated with a home sleep test.
Dentists’ Impression of Digital Impressions
In Ross’s case study, both the after apnea-hypopnea index (AHI) and oxygen desaturation index (ODI) were reduced into the normal range with the computer-aided design and computer-aided manufactured (CAD/CAM) oral appliance. The after respiratory disturbance index (RDI), although not in the normal range, was also lower. “Although this study had only one subject, this practitioner’s experience with digital scans for fabrication of orthodontic appliances has been very successful, and this study indicates it will also be true for impression-less fabrication of dental sleep appliances,” the poster states.
Appliances made from digital impressions are touted as more accurate than those made from conventional dental impressions by both manufacturers and dentists who employ a digital workflow. “It’s very, very accurate,” says Elliott Alpher, DDS, DBCP-DSM, founder and director of The Alpher Center for Sleep Disorders & Jaw Pain PC in Washington, DC and an AADSM member. He has been beta testing a digital scanner by CAD Blu, which provides CAD/CAM solutions for industries such as jewelry making. “These scanners have been used to make blades for jet engine turbines because they are so accurate.”
Speed is another advantage, Alpher says. “A digital impression can be completed in as quickly as 3 minutes,” he says, versus about 15 minutes using the conventional method.
And, similar to other scenarios in which digital alternatives have emerged, there is a space savings. It eliminates the need to store impression material or models. The impression is saved and transmitted digitally and can be duplicated numerous times with no quality loss.
Alpher’s motivation for trying digital sleep dentistry is to be able to provide convenient oral appliance solutions for truckers with sleep apnea. “The idea is if we can scan truckers in Florida and email the model to the laboratory, then by the time the trucker reaches Maine, we could have an appliance waiting for him,” Alpher says. “We want to develop a network of people to make sleep apnea therapy nonintrusive in their lives.”
He adds that digital scanners will offer an advantage in situations in which a large number of people need to be scanned in a short period of time. “The use will be tremendous in that you can go to a meeting and scan a bunch of people right then and there. You’d email it all in, and in a week they can all have their appliances.”
Then, Now, and the Future
Paul Feuerstein, DMD, in private practice general dentistry in North Billerica, Mass, has been dabbling in digital dentistry for decades. While he does not practice sleep dentistry, he is a pioneer in digital dentistry as a field, using it for items such as crowns. He tests products such as intraoral scanners for a wide variety of manufacturers.
“This is the 30th anniversary of CEREC, which was the first truly commercial CAD/CAM product that could take a digital impression and create a restoration in the office,” Feuerstein says. He notes that, in the past few years, manufacturer competition in the digital dentistry sphere has increased exponentially. The space jostling, he says, has sparked technological improvements. “They keep getting faster, more accurate, and easier to use,” Feuerstein says.
Dental lab Great Lakes Orthodontics Ltd has been designing and fabricating splints and night guard appliances using scan data for nearly a decade and began accepting intraoral scans in 2012. “We invested in a digital system for splints because the accuracy of the system created a superior product. The acceptance of doctors’ scans was driven by the marketplace,” says Great Lakes president and CEO Jim Kunkemoeller. Great Lakes accepts files from a wide array of intraoral scanners and uses a Stratasys 3-D printer to help bring them to life.
“We see better accuracy and consistency in the digital impressions we receive,” Kunkemoeller says. “When we are able to use digital systems for appliance fabrication, we also see improved accuracy and consistency.”
Kunkemoeller says these increases in accuracy and consistency will be positive for all stakeholders and expects that digital sleep dentistry will continue to grow. “Once a greater variety of FDA-approved 3-D printing materials are developed, the type and variety of appliances that can be fabricated using these technologies will increase dramatically.”
Anja Engblad, global media and event manager for Denmark-based digital scanning company 3Shape A/S, agrees digital dentistry will grow in the coming years. “Once integrated digital workflows, from digital impressions in the chair all the way to CAD/CAM manufacturing, are offered by most labs and manufacturers, analog processes will fade away—much like they have on the dental restoration market since the emergence of CAD/CAM systems,” Engblad says. “Sleep dentists have not been an initial target segment for our solutions, but we see more interest from this segment.”
Engblad adds, “Sleep appliance design and manufacturing are typically more complex than for other types of orthodontic appliances and have to take into account critical clinical parameters. For this reason, the adoption of integrated CAD/CAM tools such as [the company’s] TRIOS and Appliance Designer is on the rise, since they offer better fitting appliances and streamlined manufacturing workflows.”
Barriers to Entry
Alpher also says digital dentistry is the wave of the future, but he notes several barriers to entry for sleep dentists.
“Right now, there is a huge learning curve,” Alpher says. “Scanners are user sensitive; you have to learn what’s acceptable and what isn’t and how to get around certain areas.” He adds that not every scanner is built for every patient’s mouth. “Certain anatomic structures can’t be scanned accurately because you can’t fit the handpiece in the proper position.” He says increased simplicity of use will motivate more dentists to enter the digital realm.
Price, he says, both for dentists and for dental labs, is a barrier. Dentists have to invest in the digital scanner and may determine the increased accuracy and speed aren’t worth the large initial financial outlay. And since few dental labs currently have the ability to accept the scans (a 3-D printer can cost hundreds of thousands of dollars), dentists who offer digital impressions are limited as to what labs can process them.
Making the Model
Processing at the lab can take several forms. While this article won’t cover them in depth, in short, milling, 3-D printing, and laser sintering are common ways CAD/CAM models are made. Some of these can be done on-site at dentists’ and orthodontists’ offices if they are willing to pay for the additional equipment. “Many dentists want to just take impressions and not deal with design and manufacturing in the office,” Feuerstein says.
Great Lakes primarily employs 3-D printing for the scans it receives. It uses one of Stratasys’ seven dental 3-D printer options. In general, print time ranges from approximately 5 minutes to 20 minutes per dental model, depending on a printer’s specifications.
Stratasys is motivated to see more dental labs incorporate 3-D printing and is playing a part to remove dental labs’ barriers to entry. “We offer 100% leasing. Usually, if a lab goes with the lowest cost solution, it’s about $800/month,” says Avi Cohen, director of global dental for Stratasys. It also keeps its dental materials’ price (ie, the equivalent of printer “ink”) in line with what labs can afford, Cohen says.
Cohen says the most important attributes to consider when purchasing a 3-D printer are accuracy, productivity, reliability, cost for the printing material, and commitment to the dental market.
And as more labs accept digital scans, more sleep dentists may be willing to offer them to their patients—which could change patient apprehension toward dental impressions into excitement at being able to conveniently treat their sleep apnea.
Sree Roy is editor of Sleep Review. Send comments and questions to [email protected]
This video by Stratasys explains digital orthodontists in layman’s terms.
Considerations for Dentists Choosing Between Digital Impression Systems
- Accuracy. To how many microns is it accurate?
- Handpiece size. Does it fit comfortably in your hands?
- Teeth spray requirement? Some scanners require spraying the patients’ teeth with powder so shine doesn’t distort the lens.
- Speed. The time it takes to accurately scan a full arch varies system by system.
- Ease of use. How steep is the learning curve?
- Method of acquisition. Some scanners shoot video; others use a fast-shooting still camera.
- Quality and reliability of tech support.
- Price. Include monthly fees and service contracts.
- Commitment to the dental market.
- Lab acceptance. Check that the lab you use/want to use accepts digital scans.