Benchtop Scanners Becoming Increasingly Valuable Tools
Accuracy, architecture, software options, and more continue to evolve
By Michael Dominguez, CDT, TE
On a typical morning, the author walks into his laboratory in the Capitol Hill neighborhood of Seattle, Washington and is greeted by UPS packages ready to be unpacked. These are not new cases, or cases coming back from try-in. They are packages filled with milled copings, full-contour zirconia crowns, gold crowns, lithium disilicate crowns, implant abutments, bridge frameworks, or waxups sent from select automated production centers ready to move on to the next step. Each of these cases had been scanned and designed in-house, given a unique identification number, and exported to a production center. Cases that arrived the previous day have already been fitted, cut back, crystallized, or scanned, ready for the next steps in the digital workflow process. Although the author’s laboratory is a small two-technician operation, his two benchtop scanners offer the ability to produce a wide array of high-quality restorations in a highly efficient production process.
The scanning technology we take for granted today was not always as sophisticated, flexible, accurate, or user-friendly. The aim of this article is to provide a snapshot of the current state of benchtop scanners in the dental laboratory industry. It will start with a historical perspective and summarize the incremental improvements over the years as well as address what can be accomplished with benchtop scanners as accuracy and flexibility continue to improve. Finally, the article will explore how these tools have begun to mature in our industry by taking a general look at the different types of scanners on the market and the standards that accompany them and their software.
A Quick Scan of the Past
The benchtop scanner has become a common tool in today’s dental laboratory. In a recent survey, among laboratories offering digitally fabricated restorations, 68% of 1- to - 10-person laboratories said they had at least one scanner, and 100% with 11 or more people had at least one.1 Of those smaller laboratories, 47% have more than one scanner. Given the prevalence of digital scanning technology in the industry today, it may be a surprise to learn that the early developments in CAD/CAM technologies were first applied to clinical applications rather than indirect laboratory processes.
The CAD/CAM revolution began in 1971, with the pioneering spirit and vision of François Duret, DDS, DSO, PhD, MS, MD-PhD. His early efforts eventually resulted in the development of the Sopha® clinical CAD/CAM system, which directly impacted the 1985 introduction of the CEREC chairside scanning and milling system developed by Werner H. Mörmann, DMD, DDS, PhD. In the interim Matts Andersson, DDS, PhD, developed the first laboratory-centered CAD scan, design, and production process — the Procera® system.2,3 Andersson was also credited with developing the spark erosion process for CAD/CAM fabrication of titanium copings to offset the high cost of gold-based restorations. These pioneers quickly realized that CAD/CAM processes, although initially rudimentary, would improve the accuracy and versatility of restorative production outcomes in the dental laboratories and dental practices of tomorrow.4 As with most technological developments,5 when we look back, we can see the slow, incremental advancements over a long period of time (1971-2000) that have led to today’s modern scanning technology and the exponential growth curve from 2001-16 that most often results in the disruption of an industry.
Restorations, Implants, and Planning: An Array of Accuracy
The efficiency and accuracy of today’s CAD scanning technology make it a powerful tool that can be used for producing highly accurate and naturally esthetic restorations.6 Benchtop scanners tout an accuracy that ranges from 5-30 µm, using as many as five cameras to capture the topography of the model or impression. When provided with an accurate impression, today’s technicians can scan the impression or poured model or work directly with digital impression scan data to efficiently produce highly accurate margins, natural tooth morphology and anatomy, as well as anatomical substructures and abutments.7,8,9,10 These technological developments paralleled advancements in increased accuracy of implant restorations and abutments.
Although a purely passive fit remains elusive using either traditionally cast or CAD/CAM produced implant-supported bridges,11 the reality is that accurate impressions, verified models, and accurate scans achieve a better fit today than in the analog past. Accurate CAD/CAM produced bridges are more stable than traditionally manufactured bridge frameworks because the use of technology reduces the occurrence of vertical gaps in fit, which can introduce stress to the restoration and implants.12,13 In addition, an accurate digital workflow process saves the technician time and materials by eliminating the porosity evident in traditionally cast frameworks and the inherent weakness of solder joints that make the structure susceptible to strain or distortion during subsequent steps in fabrication.14 Today, using CAD/CAM processes we can even mill or laser sinter titanium substructures, layer them with modern titanium porcelains, and fire the restoration without impacting the accuracy or precision of the framework or fear of fracture or failure.15
Advancements in scanning and CAD technologies have pushed the capabilities of today’s scanners into more complex applications. Some benchtop scanners now have the ability to incorporate diagnostic waxups or digitally design implant-supported restorations using DICOM files produced from a CT scan to treatment plan implant surgery. Using digital implant planning software, along with a high-resolution CT scan, and a benchtop scanner, highly accurate implant placement and the final restorative outcome can be planned prior to surgery with input from both the technician and the clinical team. A surgical guide can then be milled or 3D printed to ensure the predictability and efficiency of the implant surgery along with the fabrication of accompanying components such as custom healing abutments, screw-retained temporaries, implant abutments, and the final restorations.16,17
The benchtop scanner offers the skilled and knowledgeable technician the ability to fabricate accurate and complex cases that still exhibit the highly esthetic and delicate dental art of traditionally produced restorations in a more efficient manner and one that also serves to digitally document each case and the materials used. The benchtop scanner remains just a tool, and it requires a knowledgeable technician with a strong foundation in prosthodontic fundamentals.18 Just as intraoral scanners in a clinician’s office will only be as good as the operator,19,20 benchtop scanners will only be as good as the technicians who use them. As the old proverb goes: “A bad carpenter blames his tools.”
Scanners Maturing on Exponential Growth Curve
In the past few years, lines have blurred between the two primary types of benchtop scanner file formats, but generally there are still “open” and “closed” architecture scanners. An open architecture scanner is one that allows the laboratory to send the scan data file to any in-house open-architecture mill/printer or out to any facility that accepts files for fabrication. The laboratory may decide to use one or more facilities based on what restoration or component is being fabricated. In a closed system, the file format is proprietary and the user is limited to sending scan file data to CAD/CAM production equipment and milling facilities capable of accepting that particular encrypted file format. Those conventions are breaking down as some closed systems offer added flexibility to send a file to partner facilities or equipment, but a surcharge for doing so should be expected.
After considering accuracy, scan speed, and specific types of restorations to be designed, both closed and open scanners have advantages and disadvantages to consider.21
With an open-architecture scanner, choosing the technology and software that best meet the needs of the laboratory is equally important as choosing the company from which to purchase the scanner. Considerations include the company’s level of equipment service and reputation, its viability as a company, and its history of customer support. Partnering with the right milling facility is also crucial. A milling center that is knowledgeable about the brand of scanner you have purchased and is willing to work with you to get up and running quickly is paramount.
If you have chosen a closed system, you will traditionally have strong technical support, as the company is intimately knowledgeable on all aspects of your scanner hardware and CAD software. Typically, there are also fewer fluctuations in initial accuracy outcomes from compatible milling centers because every CAD and CAM variable has been examined and tested by the manufacturer. In closed systems, laboratories are limited to the materials the company produces and are affected if they stop carrying a particular product. In either case, look closely at the fine print before inking a deal and never be rushed to close.
A laboratory that buys a second or third scanner has different purchasing considerations than the laboratory buying its first scanner. Should an additional scanner complement the existing one and not be redundant, or it will it replace an aging scanner that is facing obsolescence? This is most applicable to small laboratories, as capital may be more limited. In the author’s two-technician laboratory, the two scanners complement one another and each has a specific production role.
Owners purchasing their first scanner should make some deep evaluations. Integrating scanning technology into the production process will be a fairly large paradigm shift and can be a very successful strategy if executed for the right reasons.
If your business decision is being driven by sentiments such as, “Because so many laboratories have them and I hear my dentists talk about CAD/CAM all the time,” or, “They are everywhere and I feel I am being left behind,” then you are reacting to the pressures of the market. However, reacting solely to market pressure may not be the best decision. The author bought his first scanner in 2009 to produce titanium copings and design implant abutments. His decision was product-driven, but soon he realized the benefits of production efficiencies that reduced or eliminated manual tasks, such as waxing, and allowed him to concentrate on restorative aspects that brought value to the products being fabricated, such as the CAD design, artistry, and even the business sides of the production processes.
Conclusion
The benchtop scanner has become a contemporary tool for fabricating an array of restorations and components. The market for scanning technology has increased as the advancement of production and material technologies has expanded. It has helped to level the playing field for small businesses and allowed the industry to concentrate on production efficiencies as well as the esthetics of the end product. As the technology continues to mature and becomes mainstream in our fabrication processes, market growth of this and other emerging technologies in our industry will become standard production protocol. These are engaging times in the dental technology industry, but don’t become complacent. If the past is prologue, new innovations are on the near horizon. So stay tuned; it will get even more interesting very quickly.
Michael Dominguez, CDT, TE, is the owner of Kymata Dental Arts in Seattle, Washington.
Implant Abutments and 510(k)
Benchtop scanners for dental laboratories can assist in the design and production of many components, including implant abutments. Pre-loaded implant design software that comes with the scanner or implant CAD design add-on modules offer a variety of implant design capabilities. It is important to know that implant abutments are considered medical devices and fall under FDA regulations. As medical devices, they need to be 510(k) cleared. This is one of the primary points of confusion when dealing with CAD/CAM abutment manufacturing or design.22
The simplest way to ensure you receive components that are 510(k) cleared is to ask the manufacturer of the implant component, scanner, or software, as well as the production center milling your designs if what they sell and produce are 510(k) cleared. Eric Thorn, Esquire, counsel for the NADL, echoes this sentiment and adds, “A milling center that has obtained 510(k) clearance to market an abutment has documented their compliance with the quality systems regulations in 21 CFR 820 and validated the abutment’s design pursuant to the applicable ISO standards.” Other resources for 510(k) clearance are available in the reference section.23,24,25,26
References:
1. Fishman, J. Dental Technology Survey. LMT. 2015.
2. Miyazaki, T et al. A Review of Dental CAD/CAM: Current Status and Future Perspectives from 20 Years of Experience. Dent. Mater. J. 2009; 28.1 44-56.
3. Mörmann, WH et al. Chairside Computer-Aided Direct Ceramic Inlays. Quintessence Int. 1989; 20.5.329-39.
4. Duret F, Preston J. CAD/CAM Imaging in Dentistry. Curr Opin Dent. 1999; 1.2 150-4.
5. Diamandis P & K. Abundance: The Future Is Better Than You Think. Free Press. 2012.
6. Komine F, Blatz M, Matsumura H. Current Status of Zirconia-Based Fixed Restorations. J Oral Sci. 2004; 52.4. 531-539.
7. Miyazaki T, and Y Hotta. CAD/CAM Systems Available for The Fabrication of Crown and Bridge Restorations. Australian Dental Journal. 2009; 56. 97-106.
8. Litzenburger A, et al. Fully Automatic CAD Design of the Occlusal Morphology of Partial Crowns Compared to Dental Technicians' Design. Clin Oral Invest. 2012; 17.2. 491-496.
9. Kollmuss M, et al. Comparison of Biogenerically Reconstructed and Waxed-Up Complete Occlusal Surfaces with Respect to The Original Tooth Morphology. Clin Oral Invest. 2012; 17.3. 851-857.
10. Anadioti E, et al. Internal Fit of Pressed and Computer-Aided Design/Computer-Aided Manufacturing Ceramic Crowns Made from Digital and Conventional Impressions. The Journal of Prosthetic Dentistry. 2015; 113.4. 304-309.
11. Hecker DM, Eckert SE. Cyclic Loading of Implant-Supported Prostheses: Changes in Component Fit Over Time. The Journal of Prosthetic Dentistry. 2003; 89.4. 346-351.
12. Lyons A, J, K. Effect of Vertical Misfit On Strain Within Screw-Retained Implant Titanium and Zirconia Frameworks. Journal of Prosthodontic Research. 2012; 56.2. 102-109.
13. De Torres EM, et al. Correlation Between Vertical Misfits and Stresses Transmitted to Implants from Metal Frameworks. Journal of Biomechanics. 2011; 44.9.1735-1739.
14. Katsoulis J, et al. Precision of Fit of Implant-Supported Screw-Retained 10-Unit Computer-Aided-Designed and Computer-Aided-Manufactured Frameworks Made from Zirconium Dioxide and Titanium: An in Vitro Study. Clinical Oral Implants Research. 2012; 25.2 165-174.
15. Katsoulis J, et al. In Vitro Precision of Fit of Computer-Aided Designed and Computer-Aided Manufactured Titanium Screw-Retained Fixed Dental Prostheses Before and After Ceramic Veneering. Clinical Oral Implants Research. 2013; 26.1.44-49.
16. Spinelli D. Full Rehabilitation with Nobel Clinician and Procera Implant Bridge: Case Report. Oral & Implantology. 2013; n. pag.
17. Mandelaris GA, Vik SD. Guided Implant Surgery with Placement of a Presurgical CAD/CAM Patient-Specific Abutment and Provisional in The Esthetic Zone. Compendium Contin Educ Dent. 2014; 35.7.494-504.
18. Battersby J. CAD/CAM – The End for Dental Labs or A New Beginning?. Dentistryiq.com. 2014. Accessed December 19, 2015.
19. Tsitrou EA, Northeast SE, Van Noort R. Evaluation of the Marginal Fit of Three Margin Designs of Resin Composite Crowns Using CAD/CAM. Journal of Dentistry. 2007; 35.1.68-73.
20. Lee SJ, MacArthur RX, Gallucci GO. An Evaluation of Student and Clinician Perception of Digital and Conventional Implant Impressions. The Journal of Prosthetic Dentistry. 2013; 110.5. 420-423.
21. DR. Hollenbeck K, Dr. Allin T, Dr. Van Der Poel M. Dental Lab 3D Scanners – How They Work And What Works Best 1st Ed. 3Shape. 2012.
22. Shim C. Various Factors Affect Quality of CAD/CAM Custom Abutments. Inside Dental Technology. 2015; 6.10.
23. CFR - Code of Federal Regulations Title 21. accessdata.fda.gov. 2016. Accessed January 7, 2016.
24. Guidance for Industry and FDA Staff - Class II Special Controls Guidance Document: Root-Form Endosseous Dental Implants And Endosseous Dental Abutments. Federal Drug Administration. fda.gov. 2016. Accessed January 7, 2016.
25. Custom Device Exemption Guidance for Industry and Food and Drug Administration Staff. 1st ed. section V, subsection I, K, L. FDA, CDRH. https://www.fda.gov/downloads/medicaldevices/deviceregulationandguidance/guidancedocuments/ucm415799.pdf. 2014.
26. 510(K) Premarket Notification Accessdata. Federal Drug Administration. fda.gov. 2016. Accessed January 7, 2015.
