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Second Opinion

Digital Evolution or Revolution?

by Dennis J. Fasbinder
DDS, MAGD, ABGD



Second opinions are common in health care; whether a doctor is sorting out a difficult case or a patient is not sure what to do next. In the context of our magazine, the first opinion will always belong to the reader. This feature will allow fellow dentists to share their opinions on various topics, providing you with a "Second Opinion." Perhaps some of these dentists' observations will change your mind; while others will solidify your position. In the end, our goal is to create discussion and debate to enrich our profession.

— Thomas Giacobbi, DDS, FAGD
Dentaltown Editorial Director
 Dentistry is a continuous process of discovery, education, practice, and evaluation in order to implement new ideas for patient treatment. Consider the materials and techniques used today; to what degree have they changed from 10 or even five years ago? A technique that is as commonplace as bonding to tooth structure has changed drastically in the materials and techniques since its introduction 50 years ago. Consider how rapidly implants have moved from being introduced for the retention of complete dentures to the preferred treatment for the replacement of single teeth.

Evolution can be defined as a process of continuous change or progressive development. This generally describes the development and implementation of new treatment techniques in a modern dental practice. When new materials or equipment are discovered, their implementation relies on exploring the possibilities these new techniques offer. Through utilization and evaluation, efficacy is established, which leads to widespread acceptance as it pertains to patient treatment.

Change is not always considered a welcome addition to a well-managed dental practice as it challenges the existing, comfortable ways of doing things. A well-managed, modern dental practice employs protocols for patient treatment that have been refined to maximize productivity and the predictability of the patient's treatment outcome. A common way to evaluate new technology is to consider how it can be integrated into existing practice protocols. Protocols are important to be sure, but often overlooked is the most obvious benefit of new technology – the potential to significantly improve the patient's experience and treatment outcomes.

"Revolution" can be defined as a sudden or radical change in the way of thinking or acting about something. Revolutions are often marked by drastic events that initiate dramatic changes. The effectiveness of revolutionary change is often viewed retrospectively, as the ability to predict the significance of a new idea depends on the clarity of one's crystal ball.

Significant new technology has been introduced that can acquire optical images of the dentition that is described as a digital impression system. Is this an evolutionary change or a revolutionary one? Conventional treatment protocols follow the tooth preparation-final impression-laboratory fabrication-delivery sequence for both cast and ceramic restorations. The Itero (Cadent) or Lava COS (3M ESPE) in-office units are designed to record digital impressions of the patient's dentition. On the surface, these systems appear to be an evolution of the final impression phase of the conventional treatment sequence. In considering implementation of digital impressions, several questions come to mind. How accurate are these systems compared to the conventional analogue impression techniques? How time consuming is a digital impression compared to conventional impression techniques? What is the cost/benefit ratio of a digital impression compared to a conventional analogue impression? Although valid questions, they illustrate a limited consideration of the potential application of digital impressions.

Digital impression technology for restorative dentistry has been evolving for more than 20 years. The CEREC system (Sirona) relies on the ability to capture individual intraoral images with a CCD camera to record the cavity preparation to a computer software program for design of the restoration. A series of individual images can be stitched together by the computer to create a quadrant size model in the software program. The ability to digitally record the cavity preparation provides the opportunity to design, mill, and deliver ceramic restorations in a single appointment. This has been a significant development for restorative dentistry.
"If we indulge in a little futuristic thinking, there are a number of additional potential uses for the digital impression data." The Lava Chairside Oral Scanner (COS) records a digital video of the quadrant or arch. This can be done in a single pass of the camera wand over the dentition or with a series of smaller scans that can be combined into a single scan. Digital scans are recorded of opposing arches or quadrants. The centric position of the arches is scanned from the facial to fix the relationship of the opposing arch or quadrant scans in the digital file.

The Lava COS system has two treatment protocols for fabricating restorations. Once the digital impression has been completed, the data is uploaded to a Web site where it can be downloaded by a laboratory design center and the data processed for the fabrication of a resin model using stereolithography (SLA model). This consists of a laser micro-curing process that creates opposing arch models and allows them to be mounted according the scanned data. The SLA model is then available for the fabrication of dental restorations using the gamut of traditional laboratory fabrication processes. A second option is for the laboratory design center to directly input the digital impression data directly into the Lava CAD/CAM software program and fabricate zirconium-based restorations. The SLA model is then used to complete the veneering process of the zirconium substructure. Digital impressions offer a significantly better treatment experience for many patients by avoiding the unpleasantness of a conventional analogue impression. In the simplest form, digital impressions can substitute for the analogue impression technique of recording impressions of opposing arches and a bite registration. However, this is still a limited view of the potential application for digital impression data.
If we indulge in a little futuristic thinking, there are a number of additional potential uses for the digital impression data. The digital data might be of significant use for diagnostic procedures. Computer software might be able to quantitatively compare digital scans between two time periods. This could measure changes in such items as tooth position, the degree of soft tissue recession, restoration damage or tooth wear. This would provide quantitative information that could influence treatment decisions for early intervention to prevent further undesirable change or damage. The ability to quantify change over time would also be of significant value in dental research as new restorative materials are introduced. The potential ability to use private practice digital impressions to evaluate changes in the dentition could be a significant new source of information. The digital data might have potential diagnostic applications for orthodontic treatment. Computer modeling of treatment alternatives might provide a means to visualize changes, consider alternatives, and monitor possible alterations in treatment outcome. If patients were to have complete dentition digital impressions as part of the new patient examination, it might be possible to use archived digital impressions of patients to create new restorations replicating the patient's dentition as new disease or problems dictate.

Another consideration is the potential to move the dental laboratory and dental clinic closer together in collaboration on patient treatment. The digital impression data would be simultaneously available to both the laboratory technician and the dentist. This would enhance communication for both diagnostic and treatment discussions of cases. Storage of digital impressions would be significantly improved over current techniques of storing stone models. They would also be available to transmit around the world as patients moved between treatment providers. Another element to consider is to what degree does a digital impression improve the patient experience? Digital impressions might be considered a more comfortable alternative to analogue impressions from the patient's point of view.

A potentially overlooked benefit of the digital impression is the significant improvement in visualization of the recorded data. The computer monitor displays the scanned tooth preparation at least 15-times greater than life-size. It provides immediate feedback on the preparation in progress. The preparation can easily be evaluated for appropriateness in design, degree of clearance from opposing teeth, and its relationship to other teeth in the arch. This might prove to be an invaluable benefit for dental education. Rather than relying on the artistic ability of the instructor to communicate with students by drawing changes desired in student preparations, students would have the ability to immediately scan and evaluate their preparations. It might also be possible for the digital data to be evaluated by a software program for the degree of taper, clearance from opposing and adjacent teeth, and other preparation features as to the appropriateness of the preparation design for the desired planned restoration.

Some might question the ability to perform excellent restorative dentistry without the benefit of stone models. This will be a function of the willingness to embrace the digital realm rather than try to fit it into existing treatment protocols. As stated earlier, integration is important but the redefinition of the patient experience with technologies that produce results equivalent to that produced today in an analog fashion should be our objective.

So, evolution or revolution? On the surface, digital impressions might be considered the continual evolution of the conventional impression process. However, it would seem that this is a limited view of the technology. Digital impressions are a redefinition of what we currently do today through the total elimination of materials and techniques that few dentists find appealing, yet find comforting. Digital impressions are a revolution in the making, and comfort aside, the futuristic view would be to embrace the revolution. The reason is clear; digital technology will improve the patient experience while sacrificing features that the dentist and the patient really do not like anyway. Not comfortable for us probably, but whose comfort is your practice all about?
Authors' Bio
Dr. Fasbinder is a clinical professor in the Department of Cariology, Restorative Sciences and Endodontics, at the University of Michigan School of Dentistry and is the Director of the Advanced Education in General Dentistry Program. He is board certified in general dentistry by the American Board of General Dentistry. He also maintains a part-time private practice in Ann Arbor, Michigan. He is a founding member of 21st Century Practice Solutions comprised of some of the top experts in CAD/CAM and technological applications for dentistry. He directs the Computerized Dentistry Unit at the University of Michigan School of Dentistry that is dedicated to research and education on CAD CAM dentistry. Dr. Fasbinder has been doing laboratory and applied, clinical research with CAD/CAM ceramic systems since 1993. To contact Dr. Fasbinder, please call 734-647-4450 or email djfas@umich.edu.
Dentaltown Magazine
September 2025
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