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Digital workflow

Aug. 1, 2008
What is it, why should you get involved, and how is it transforming the industry?

What is it, why should you get involved, and how is it transforming the industry?

by Dan McMaster, 3M ESPE, Bob Cohen, CDT, Advanced Dental Technologies, Inc., and Steven D. Spitz, DMD, Smileboston Cosmetic and Implant Dentistry

For more on this topic, go to www.dentaleconomics.com and search using the following key words: digital workflow, indirect restorations, dentist/lab communication.

Dan McMaster: For many years, the way that dentists and labs communicate to create indirect restorations has remained largely the same. The dentist takes an impression, ships his or her prescription to the lab, and waits two weeks for a finished restoration to be returned — which may need minor or major adjustments despite the best efforts of the dentist and lab tech.

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While the communication has remained the same, we've watched as restorative materials and production processes have significantly evolved. The popularity of ceramic restorations such as zirconia is increasing rapidly, along with the CAD/CAM processes used to produce them, while the percentage of PFMs being placed is decreasing. At the same time, a shortage of dentists and dental lab technicians is creating an increased need for improved productivity. So while patients are demanding more sophisticated restorations and better esthetics, dental offices and laboratories are looking for ways to meet that demand efficiently and without compromising quality.

It's a tall order, but it's one that we at 3M ESPE have been studying for some time. With recent breakthroughs in technology, we have developed a process that will help dentists and labs meet these challenges. It's a digital workflow process, and some of our customers are already experiencing the dramatic changes the system can bring about. Because the process is so different from the current method of production, it may seem complicated at first glance, but ultimately digital workflow drastically streamlines procedures for both the dentist and lab.

Entry points to digital workflow

Many labs have already been working with an important tool in the transition to digital workflow. The Lava™ Scan ST Design System allows labs to create digital models from traditional impressions and then design restorations electronically. This is accomplished by scanning the impressions in the Lava Scan ST Scanner, and then creating the design with the accompanying Lava™ Design Software 4.1. To allow labs further flexibility and options within the digital workflow, 3M ESPE selectively opens the Lava Design System to make it compatible as the front-end to other production systems. This enables it to be used for multiple materials and indications, including wax/resin patterns, laser-sintered metal, and custom implant abutments. This system offers labs both large and small a versatile and cost-effective entry point into digital workflow. As the technology evolves, the Lava design system will continue to serve as the digital hub of the modern laboratory.

Now, digital workflow is becoming available to dental offices, as well. 3M ESPE, the worldwide leader in impression solutions, has recently introduced a digital impression system, the 3M™ ESPE™ Lava™ Chairside Oral Scanner C.O.S. The Lava C.O.S. provides an exciting and highly accurate digital alternative to one of the most challenging and historically manual dental procedures. With traditional impressioning methods, any number of factors can create the potential for laboratory restorations that don't seat properly, have poor contacts, or may require occlusal adjustments. However, with the Lava C.O.S., the dentist uses a wand slightly larger than an electric toothbrush in the patient's mouth to capture continuous 3-D video images. Other current digital impression technology requires users to take pictures, and each picture captures one 3-D data set. The Lava C.O.S. captures 20 3-D data sets per second, or about 2,400 3-D data sets per arch, creating precise measurements with which a lab can design the best-fitting restoration. The system uses high-speed image processing algorithms and real-time modeling software to create the digital impression. Another exciting and unique feature allows the dentist to see the data modeled simultaneously on the accompanying touch-screen monitor, and receive instantaneous feedback to ensure that all essential data is captured while the patient is still in the chair.

Once the scan is complete, the dentist has the ability to review the scan through 2-D enhancement, video review, or 3-D stereographic review. This allows the dentist to scrutinize and address his or her work in ways that were never possible with a traditional impression. Once the impression meets the dentist's approval, he or she fills out an electronic prescription. The Lava C.O.S. software is not limited to producing only Lava restorations; it can be used for traditional PFMs as well, and 3M ESPE plans to make the Lava C.O.S. compatible with selected CAD/CAM systems in the future. Thus, dentists will be allowed to prescribe according to their preference and their patients' wishes.

Margin marking and die-cutting

The digital workflow process continues after the lab receives a dentist's digital impression file. With this data, the technician uses software to digitally mark the margins and cut the dies on the restoration. The software allows the technician to see exactly what the dentist captured in the mouth, and mark the margins using 2-D enhancement, video review, or 3-D stereographic view. When working with a digital impression, technicians get a comprehensive picture of the dentition, and features that would have previously been ambiguous or appeared to be tooth anatomy on a plaster or 3-D model (cord in the way, for example) can be better identified. The quality of the digital impression means that communication between the dentist and lab can be improved dramatically, and discrepancies can be identified and managed much differently.

Ditching and model production

Once the margins are marked and dies cut, the data is sent to 3M ESPE where the puzzle pieces are put together. In a largely automated process, the bite scan is aligned with the operative and opposing. The models are digitally ditched and then sent to a stereolithography (SLA) facility for model production. SLA is a rapid prototyping technology in which models are created with a light-sensitive polymer resin material, eliminating the laboratory step of pouring plaster. Statistical process control is built into the SLA model process to ensure accuracy — every batch of models is calibrated and measured across 117 dimensions, and in the very rare instance that any measurement is out of tolerance, the entire batch is remade.

The model production facility assembles the cut model and opposing in an articulator and ships them, along with a separate solid "check" model, back to the lab. In the traditional PFM workflow, once the lab receives the model from the production facility, the building of the restoration can begin in much the same way it is done with stone models today.

Additional efficiencies for zirconia

The process is streamlined even further with Lava™ zirconia restorations. The initial steps are the same, with the dentist taking the digital impression; the lab then marks the margins and virtually defines the die cuts, and 3M ESPE aligns the bite registration with the operative and opposing. The difference comes at the next point in the workflow: while the virtual model created by 3M ESPE is sent to the SLA facility, it is simultaneously sent back to the lab for production using the Lava milling system. With this process, while the coping is being milled, the model is also being manufactured at a separate location. The digital data captured with the Lava C.O.S. eliminates the need for a model to mill a Lava coping — the model is only used in the final steps as the porcelain is overlaid.

The final, completed restoration reflects the best work of both the dentist and the lab, offering a better fit and proven strength in less time, and a better patient experience. 3M ESPE has studied the restoration process from start to finish, and has produced solutions at each step of the way. 3M ESPE continues to aim to create the ultimate final restoration, and the solutions that are possible through digital workflow truly demonstrate the potential for dentistry in the 21st century.

A dentist's perspective: improved patient care and higher quality restorations

Steven Spitz, DMD: I am really enjoying this era of dentistry. There are such exceptional technologies affecting all aspects of dentistry, and integrating several systems in my practice has made a significant difference. When I begin to consider a new technology, my thoughts are: "Will this help me do better dentistry? Will it increase my productivity? Will it make a significant difference for my patients?" The Lava C.O.S. has accomplished all three goals. Utilizing the wand and monitor is almost like having a microscope — since the image is blown up, I can see all margins of the prep clearly and, if I feel it is necessary, perform another scan on the spot.

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The time saved through digital workflow in my practice is considerable. A scan for a single crown (prep, opposing, and bite scan) can be completed in under five minutes, after which the prescription is completed and sent to the lab immediately with the patient still in the chair. My assistant doesn't have to wait for me to fill out the lab slip, and does not have to spend the time to disinfect the impression, box it, or ship it out. We save at least two days in travel time for the lab to receive a case, and restorations are now back in our hands in half the time. The Lava C.O.S. technology also makes communication with the lab and throughout my office much easier. In the delivery of crowns, there are virtually no adjustments, and the time it takes to seat crowns has decreased remarkably (over 50%).

Additionally, patient comfort and the ability to educate patients have always been priorities for me in my practice. I believe that when patients are educated, they can truly understand their treatment plan and how it will affect them in the long run. Discussing scans with patients when they can actually visualize the outcome of the procedure allows them to understand and make better decisions, and my patients' reactions to the scanner have been extremely positive. As a prosthodontist, diagnostic models are the first step in my treatment plan, and therefore, nearly every patient I treat has had experience with impression material. The obvious improvement, especially for those with a gag reflex, is having impressions taken without material. Not only are they appreciative of the technology, they are mesmerized watching their teeth appear on the screen as the scan is being done. They now know to ask for a scan instead of a traditional impression.

In dentistry, being successful means being efficient. Over the last few years, I have considered purchasing a CEREC unit. However, I ultimately decided that my time is better spent as a dentist and not a technician, and I can count on my lab to help me be successful. By collaborating with a lab through digital workflow, I can offer a better, positive patient experience with a faster turnaround and fewer adjustments. The Lava C.O.S. technology makes a significant difference in my goal to do better dentistry and be a better dentist.

A lab's perspective: increased efficiency and better communication

Bob Cohen, CDT: When my partner and I decided to expand our lab, we considered a number of milling machines. The day we learned that 3M ESPE had moved into the oral scanning business, we made the decision to purchase the Lava system. We recognized the commitment that 3M ESPE was making to the digital workflow process. A dental customer of ours had been doing beta testing for Brontes Technologies, which developed the digital impression technology, and we knew the potential and anticipated that it would change our industry.

Advanced Dental Technologies has been an Authorized Lava Milling Center for about a year, and our lab produces 50 to 60 Lava restorations per day, some of which are made possible by the digital workflow. The key is, we can efficiently manufacture different pieces of the product simultaneously, reducing the turnaround time in the manufacturing cycle. While a turnaround time of two weeks is typical with the traditional workflow, we can reduce that to one week with digital technology. When a dentist takes a digital impression, that data can be downloaded by the lab within one hour, and we can design and mill a Lava coping on the same day the impression is taken.

The improved quality of the impressions we receive from dentists eliminates some very common problems. In a recent survey, laboratories were asked to "name their number one challenge with incoming work from dentists," and 60% of respondents stated, "Making do with inadequate work sent in by the dentist." Digital impressions address this problem head-on by giving the dentist a real-time picture of the image being made. This means that when using the Lava C.O.S., our lab does not have to worry about inaccurate impressions. Inaccuracies such as pulls, bubbles, tears, and movement of the tray simply do not apply or occur with a digital impression.

The process eliminates many of the steps to which we've become so accustomed. Having the SLA models produced at an outside facility offers a number of advantages to the lab: It reduces lab inventory and labor costs, and provides a much stronger model with a neat and clean presentation. It truly takes the lab out of the "stone age."

The efficiency and quality made possible with digital workflow is difficult to overstate. In addition to reducing inventory and labor, it reduces time lost for pick-ups, eliminates chemical-based processes, and expedites delivery of restorations. Additionally, the improved quality of the initial impression results in improved quality of the overall restoration, and fewer remakes and returns. Our technicians are adapting quite well, and are taking an interest in digital workflow. They know it's the future of esthetic and restorative dentistry. I encourage other lab professionals to embrace and believe in this technology.

Dan McMaster is a marketing manager for Lava digital restorative dentistry at 3M ESPE Dental Products in the United States. McMaster holds a BS in chemical engineering from the University of Utah and an MBA from the University of Michigan Business School.

Bob Cohen, CDT, is the cofounder of Advanced Dental Technologies in Stoneham, Mass., one of New England's leading laboratories in implant-supported restorations, full-mouth reconstruction, and esthetic dentistry. Cohen has more than 20 years of experience in the lab industry.

Steven D. Spitz, DMD, is founder and principal of Smileboston™ Cosmetic and Implant Dentistry, a Boston-based dental office specializing in full-mouth dental care. Dr. Spitz is a prosthodontist and offers care utilizing dental lasers for treatment, dental implant placement, tooth restoration, and full-mouth rehabilitation.