Digital Intraoral Impression Systems

Admittedly, some of the initial results from digitally manufactured restorations were vastly inferior to other, more traditional, methods of production. Unfortunately some of these early results have led clinicians and technicians alike to write off any and all similar technologies after over 20 years of refinement. The digital intraoral impression devices of today (and tomorrow) like Glidewell’s IOS FastScan® and 3Shape’s TRIOS® (Figure 1 and Figure 2) are vastly superior to what they were decades ago. Levels of marginal accuracy that surpass anything the profession has been previously able to create with lost wax techniques on stone models have been demonstrated. But marginal accuracy and internal fit are only part of the path to clinical excellence.

With intraoral digital impression devices, collaboration between clinicians and technicians can reach previously unimagined levels. Offsite laboratories can collaborate with their doctors on cases while both viewing and modifying the same three-dimensional (3D) representation of the definitive restoration. Casts—which are now more properly described as “models” because most are milled or printed, not “cast”—will likely evolve into an optional resource for the fabrication of basic restorations. More complicated prosthetic treatments will continue to require a model upon which to finalize the function and esthetics. Innovative new restorative materials that inherently require the use of a digitized model to be fabricated have been developed—for example, zirconia frameworks and prostheses that can only be milled.

Ease of use in the demanding clinical environment previously served as a significant roadblock to the adoption of digital intraoral impressions, but many of the initial problems have been overcome. No longer is an opaquing powder required with most systems, and scanning protocols have been significantly streamlined. Current systems record the intraoral environment with a series of automatically captured images or brief videos. This has greatly reduced the time required to take the scans. The scanning wands continue to decrease in size, with each iteration allowing improved access, particularly at the second molar. Additionally, some states have amended their dental regulations and permitted some classes of auxiliaries to take the digital impression for the fabrication of the definitive restoration. As computer hardware and software continue to improve both inside and outside the dental community, vast increases in capture speed and accuracy will continually develop.

Much of the recent success and popularity of digital intraoral impression systems has come about due to the development of the stand-alone scanning device. For over 20 years, digital impression systems, which included in-office milling devices, required the dental office to handle the design, milling, finishing, and fitting of the restoration. This was, and continues to be, a fairly small segment of dental practices. Introduction of the stand-alone scanning units (without a mill) allowed many clinicians to implement digital impressions into their practice without making significant changes to their standard operating procedures and doing this at only a fraction of the cost when combined with milling units. Such systems offer high returns in patient comfort, satisfaction, and perception, but they do not offer the strong potential return on investment (ROI) possible with in-office CAD/CAM systems. Many professionals in the dental laboratory industry have feared that if dentists were able to create the definitive restoration in their practice, their business would be significantly harmed. And though this may be true for some, there does not appear to be much demand for dentists to integrate a highly functioning ceramics laboratory within their own practice. Integration of in-office CAD/CAM systems has worked wonderfully for some, but there are many in-office CAD/CAM units collecting dust or available for sale in nearly unused condition to testify to the difficulties of CAD/CAM integration. Stand-alone digital intraoral impression devices, on the other hand, strengthen the dentist-laboratory relationship and allow seamless integration into a dental practice with little changes to existing, well-developed protocols and responsibilities.

Clinicians who once looked at the question of digital impressions and in-office CAD/CAM with a skeptical eye now seem to be coming around to the idea of the technology. Significant improvements in ease of use, accuracy, and efficiency have all led to a change in the perception of the dental profession regarding digital restorative technology. Many dentists previously looked at such technologies and wondered if this were something they would purchase for their practices. That question has seemingly evolved in recent years into when?

It is difficult to speculate what the future will hold for clinical dentistry, but undoubtedly we are in the midst of a significant shift into the realm of digital dentistry. As we enter this new era, we must remain steadfast in our dedication to excellence and develop techniques and materials at the highest levels available. It would indeed be sad if, as a profession, we had reached the pinnacle of care decades ago, and we were incapable of improving upon it. We should encourage and support the development and maturation of new technologies that will one day become the new “gold standards.”

Todd R. Schoenbaum, DDS, FACD, is an assistant clinical professor at the UCLA School of Dentistry, Division of Restorative Dentistry.