Is a Digital Scanner About Accuracy, Versatility, or Application?
Robert Ritter, DMD | Paresh Shah, DMD | John Weston, DDS
Robert Ritter, DMD: Intraoral scanning has changed the way indirect dentistry is provided to patients and how information is sent to dental laboratories. Dentists can also use an in-house mill to fabricate restorations while patients wait. The proliferation of intraoral scanners during the last 7 years has given the profession benefits it has never seen before. Technology and economies of scale have taken advanced digital machinery and placed it in the hands and offices of dentists, both general and specialists. The wide-ranging applications include scanning teeth for restorations and clear aligner orthodontics, as well as scan bodies for implant abutments based on the underlying implants; these are remarkable advancements because of the accuracy and precision of the algorithms.
The accuracy of chairside scanning is also important for laboratory design software and the ability of laboratories to mill zirconia and lithium disilicate within predetermined variances. The materials themselves benefit from the complete control involved in turning the analog teeth, both prepared and not prepared, into digital data (1s and 0s). The overall consistency of the process leads to less seating adjustments, a large decrease in remakes, and a reproducibility that increases the profitability of the dental office.
Ultimately, as chairside digital scanners become more affordable and the uses of the technology expand to diagnosis, collecting data, and marking changes to the dentition with time, the scanners will become as standard as handpieces and curing lights.
Paresh Shah, DMD: In my opinion, the question of whether digital scanners are accurate has been overblown for some time. Digital impression scanning has been around for more than 32 years, and according to plenty of evidenced-based information, the accuracy of the current generation of scanners is not an issue for routine restorative treatment. As far as application is concerned, for far too long manufacturers and distributors have been focused on selling scanners based on a return-on-investment (ROI) model. The ROI model is based on replacing impression materials and keeping the laboratory work in-house, but that is not the correct way to look at this technology. In my opinion, the key is versatility. The uses for scanners have evolved beyond simply replacing impression materials for crowns and bridges. A digital workflow has been shown to improve efficiency, reduce costs, and save time. The percentage of model-free restorations has increased, leading to lower costs for patients. Statistics show a reduction of remakes, adjustments, and chair time as well.
More workflows are available with digital scanners, including implants, orthodontics, and chairside milling. Many of the scanners can send cases directly to manufacturers without pouring impressions. Scan bodies can be used to take impressions that allow digital design and milling of abutments and crowns over implants. Scanners can even make an image of the emergence profile around an implant to help produce a restoration that seats in a similar fashion.
Through digital workflows, we can develop digital smile designs and mill natural-looking restorations that fit well without having to make conventional impressions. With digital scanners, we can add to a patient’s health record by using a 3-dimensional scan for accuracy, which can be used for patient education, comparison of changes over time, and treatment planning of restorative cases. The versatility of a scanner now allows a practice to move forward into the world of digital dentistry in ways that are less cumbersome, costly, and time-consuming.
John Weston, DDS: When it comes to accuracy, most clinicians want a digital impression system that captures preparations equal to or better than their current analog tray material. Accuracy is my No. 1 criterion. Studies show that most of the current systems on the market allow for the production of crowns that fit as well or better than those produced using conventional impression systems. However, even with this data, there is still a resistance from doctors to jump into the digital impression world. Why? Are there other factors that matter?
Versatility is a factor that may have a different meaning for each clinician. Most of the systems are cart-based units, which take up limited real estate that is already at a premium in dental operatories. Some recent systems are laptop-based, which have a smaller footprint, and there is also a new tablet-based mobile system. This type of portability can be a deciding factor for some larger offices with multiple chairs and doctors.
A system that has more than one application is also important. For example, orthodontists need a system that is compatible with aligner technology and digital model storage, while oral surgeons want the ability to work with implants, and general practices use scanners mostly for crown-and-bridge work. If you perform chairside milling, you would want a scanner that pairs well with one of the quality milling units on the market. Many general practitioners now want a system that can do nearly everything—fixed, removable, cosmetic, milling, implants, implant guides, and aligner workflows. They want it to be fast, easy, predictable, and portable. The problem is not every scanner can do everything, and open or closed architecture could be important when trying to use a scanner for multiple applications.
Robert Ritter, DMD, is a partner in a private practice, Ritter & Ramsey General and Cosmetic Dentistry, in Jupiter, Florida.
Paresh Shah, DMD, maintains a private practice in Winnipeg, Manitoba, Canada.
John Weston, DDS, is owner and director of Scripps Center for Dental Care, La Jolla, California.