Pamela G. Doray, DMD, MSED, FAGD, AAACD
By now,everyone has heard about the advantages of scanning dental impressions digitally. Digital “impressions” are more comfortable for patients, faster for the dental team, and are able to produce highly accurate images that contribute to restorations that seat easily and quickly. I personally have used a digital scanner for six years, and have been able to see how each successive generation of the technology has improved on the last. Today, scanners have reached a point where they are more flexible, accurate, and productive than ever before.
My current scanner is the 3M True Definition Scanner, which has greatly streamlined the workflow in my office, and not just for crown and bridge work. Very often the discussions surrounding scanners pertain just to crown and bridge applications, which is logical given how much of the average dentist’s day is devoted to these procedures. But digital scanners have capabilities far beyond crowns and bridges, which can make them even more valuable tools. It’s important for practitioners to consider not only what they might be comfortable doing with a digital scanner now, but also what additional workflows they might one day want to incorporate into their daily practices.
Understanding a scanner’s “architecture”
When considering various scanning systems, dentists should carefully examine the way they integrate with other technologies. This integration, or lack thereof, will dictate the workflows that the dentist can access. For example, the 3M system has two different categories of connections that give the dentist the opportunity to perform many other applications. These include orthodontic treatment, implant dentistry, and CAD/CAM milling of restorations.
First, there are “Trusted Connections,” which means that a workflow has been technically and clinically tested, and that dentists can expect a high level of integration and smooth communication between technologies. Currently, the 3M scanner has Trusted Connections with various technologies for chairside mills, implants, and orthodontic appliances.
In addition to Trusted Connections, the 3M scanner also produces “open” STL files, which means that the scans can be exported to any system that accepts STL files. This is in contrast to many scanner systems that are “closed,” producing files only compatible with a limited selection of workflows. With an “open” system, dentists have the flexibility to use the scanner for whatever options they would like in terms of design, materials, and production, as long as the system can accept STL files. For example, many dentists are currently taking advantage of these open connections to produce night guards or other appliances.
Reviewing a few sample workflows will help illustrate how my 3M True Definition scanner gives me flexible options for a wide variety of restorations and treatments:
Biomet 3i Implants
With this workflow, we use the scanner to take a digital impression of the Biomet 3i BellaTek Encode Healing Abutment that is in place. This healing abutment has codes on the occlusal surface that eliminate the need for an impression coping. After reviewing the scan for completeness and accuracy, we send it electronically to the BellaTek Production Center. There, a patient-specific abutment is designed and sent to my designated lab for review, after which the custom abutment is milled by the Production Center. The abutment and an SLA model of the abutment, working model, and counter model are then sent to my lab, where the final restoration is designed and finished. The lab then delivers the model, abutment, and restoration to me. For my office, this entire workflow simply involves the initial scan and electronic submission of the files, making this workflow faster, easier, and more efficient than conventional implant impression techniques. I was actually a pilot user of this workflow with the earlier generation 3M ESPE Lava Chairside Oral Scanner C.O.S. Now it works even more smoothly with the Trusted Connection to the 3M True Definition Scanner.
To create Invisalign clear aligners, we scan the full arch and review the 3-D model on the touch screen to ensure the scan has been captured accurately. We then send the scans electronically via the Trusted Connection to Invisalign. While the guidelines say to allow 90 minutes for the information to be transmitted, in my experience this sometimes takes as little as 10 minutes. On the Invisalign Doctor Site, we simply enter the patient’s information and attach his or her scan to the online prescription. Once I have approved the ClinCheck created by Invisalign, the aligners are manufactured and shipped back to me. We absolutely love this workflow and patients do too. Once again, it is faster, easier, and more efficient.
Control, versatility, and accuracy
This flexible system of both open and Trusted Connections gives me greater control of the workflows used in my practice and with our selected labs. Today, I find that nearly every lab I work with is totally on board to handle the scans or collaborate in the digital workflow with SLA models. Lab technicians tell me they appreciate that the SLA models are more durable than stone, so they won’t chip or break. The models also have very crisp, sharp detail and a better surface finish than prior generations of digitally produced models. These models and the open STL files give me the freedom to be innovative and apply my scans in different applications. The 3M system expands my ability to use the digital data and does not limit how I can apply it.
In any of the workflows discussed here, accuracy is of course paramount. I have found that digital scanning provides a level of accuracy that we cannot achieve with conventional impression-taking materials, simply due to the nature of the materials and the process. Any conventional material has to be mixed, introducing the risk of bubbles, voids, or uneven setting of the material. In addition, every material on the market has some degree of shrinkage, and every model that is poured will have some degree of setting expansion. Furthermore, conventional impressions must be disinfected, which often occurs once at the dental office and again at the lab. Each of these factors can introduce a small amount of distortion into the process with conventional techniques, regardless of the dentist’s or lab technician’s expertise.
In contrast, a digital scan gives the dentist the ability to immediately see the “impression” on the chairside screen and to magnify it to examine every aspect in detail. In addition to being much faster than a conventional impression, this process virtually guarantees that the dentist will send the lab a complete and accurate “impression.” If something doesn’t look right, it can be rescanned in a matter of seconds. It’s no longer necessary to send an impression off to the lab and hope it pours up OK.
As illustrated by the sample workflows discussed here, digital scanners have evolved far beyond typical crown and bridge applications. Today, a scanner can serve as the entry point to a long list of workflows, and dentists and labs have additional freedom to think of their own applications for STL files. As more Trusted Connections are added, dentists will gain access to even more efficient workflows.
The ongoing expansion of capabilities for these systems is great for patients, dentists, and labs. Patients get a more comfortable and consistent experience in the chair, and dentists and labs gain a tool that helps them work more quickly, efficiently, and accurately.