Developments in Intraoral Scanning

As digital dental technologies continue to gain traction, more and more dentists are adopting intraoral scanning in lieu of conventional tray impressions. While there is a place for both techniques in modern practice, scanners certainly bring advantages to the operatory — including speed, convenience, digital data capture, and, perhaps most importantly, patient acceptance. There could also be a marketing advantage in switching. Noting that many patients associate the use of technology with precision and better outcomes, Stephen J. Sterlitz, DDS, MS, ABGD, division chief in the Department of Restorative Dentistry at the University of Kentucky College of Dentistry, suggests scanning technology may give practices a leg up on the competition. 

While it’s true some cases may lend themselves to traditional impression techniques, Sterlitz’s first choice is to “use digital impressions for everything.” Patients tend to tolerate digital impressions better than analog impressions, he observes, adding that with the increased depth of field of many new scanners, deep margins are less of a concern than with the older scanning units. Regardless of the approach, he asserts the principle of taking an accurate crown impression applies to both digital and conventional methods. “If you can retract the tissue enough to see your margins, you can capture an accurate impression,” he says.

According to Sterlitz, complete dentures may be the one procedure not completely compatible with intraoral scanners. “I am still working out a technique for capturing the soft palate of an edentulous patient and the depth of the vestibule for proper flange extension,” he reports. “While a hybrid approach using analog and digital impressions to capture these areas facilitates a complete-denture workflow, I am confident we are not far away from an exclusively digital workflow for these cases.”

When asked what dentists should consider before purchasing scanning technology, Sterlitz poses this simple question to what he characterizes as a complex decision: What procedures do you want to do digitally? “If replacing analog impression material is the primary goal, that allows an office to choose from many capable and accurate intraoral scanners,” he says. “The purchase decision gets more complicated when an office is looking to add technology that supports other procedures, such as clear aligners, dental implants, or same-day all-ceramic restorations. I have seen situations in which a practice buys a scanner, but is surprised when it has to pay more to unlock permission for additional procedures. Conversely, some offices have bought expensive chairside CAD/CAM systems when they really only needed a basic scanner.” 

Addressing common mistakes in scanning technique, Sterlitz advises clinicians not to move too fast or too slow, as both methods result in avoidable errors. “Move the scanner too fast, and you could have voids in critical areas that affect the accuracy of the scan,” he says. “Move the scanner too slow, and the file size gets too large. This might also create artifacts and make the model harder to render. Besides controlling moisture and tissue, the key to a good digital impression is use of a repeatable scanning strategy.”

Noting there are multiple studies that demonstrate intraoral scanners rival the accuracy of analog full-arch impressions, he reports that only recently has this technology allowed accurate cross-arch scans that support digital workflows for printed or milled occlusal guards, as well as clear aligners. “In turn, orthodontic treatment times are reduced due to the measured and controlled movement possible with clear aligners,” he says. “Similarly, same-day restorations with chairside CAD/CAM workflows result in fewer trips to the dentist and less time away from work.” 

Pointing to advances in artificial intelligence that have flattened the learning curve, Sterlitz notes adding intraoral scanning and CAD/CAM technology is nothing compared to what it was five years ago. “The workflow has become so intuitive that providers are rapidly learning advanced techniques in a fraction of the time,” he says. “If offices have been waiting for the ‘right time’ to buy a capable and user-friendly intraoral scanner, the time is now!” 

From Decisions in Dentistry. October 2021;7(10):46.