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The future of impressions

June 1, 2007
Tens of millions of impressions are taken each year for the production of crowns, bridges, and partial dentures.

by Jeffrey B. Dalin, DDS, FACD, FAGD, FICD

Tens of millions of impressions are taken each year for the production of crowns, bridges, and partial dentures. Dentists seem to be taking a number of these time-consuming, “patient-hating” procedures daily. New systems are now available that create digital impressions of a patient’s teeth, both prepared and unprepared. These systems provide a way to dispense of trays and impression materials. These methods should lead to increased patient satisfaction and their accuracy should create better-fitting crowns and bridges. This month, I will talk with two key players from companies in this cutting edge field of dental technology: Mike Girard from 3M ESPE and Tim Mack from Cadent.

Dr. Dalin: Gentlemen, let’s start by having each of you give a short summary of your respective company’s products.

Girard: The 3M ESPE Intraoral Scanning System is a combination of unique hardware and software with a design based on the research of Professor Doug Hart and Dr. Janos Rohaly, originally at MIT, as well as development during the last three years by Brontes Technologies. Research and development has led to a sophisticated method for capturing images called “Active Wavefront Sampling.” This method enables “3-D Video in Motion” - a breakthrough in image capturing technology in which the system efficiently captures broad anatomy from the mouth. We are excited about the impact this technology will have on many facets of dentistry.

Mack: The Cadent iTero system comprises an intraoral scanner, a CAD workstation at the dental lab, and central production support by Cadent. There are no special techniques required since the dentist preps the teeth being restored and attends to normal clinical matters, such as tissue and moisture management. The case proceeds with the dentist or dental assistant completing the digital Rx. iTero then instantly develops a customized scanning sequence for that specific case. Guided by visual and audible prompts, the dentist - or more often the assistant - proceeds through the scanning sequence. During this time, the system stitches together the scans of the target area, the adjacent teeth, and the bite into a real-time digital model. This magnified digital model is presented on a flat panel display along with real-time analytical tools, which bring attention to areas that may need adjustment - for example, occlusal clearance. All of this occurs in just three to four minutes. Adjustments may be made and additional scans taken after which the digital file is transmitted to a participating dental lab. The lab completes the computer-aided design (CAD) and uploads that design to Cadent. The models, removable dies, and copings - if requested - then are produced at Cadent’s production center in New Jersey and delivered to the dental lab for completion of the restoration.

Dr. Dalin: Most dentists are familiar with CAD/CAM systems like CEREC and the newly released E4D. I know each of these takes a digital image of a prepared tooth and then sends this information to a milling device to create a final restoration. How do your systems differ from what is used in these two existing systems?

Girard: From the onset, Brontes Technologies had a clear vision that the system would offer dentists and laboratories a technology that would enable a range of restorations that a user could prescribe, both conventional and CAD/CAM. The unique technology used in the 3M ESPE imaging device allows the user to move freely throughout the mouth capturing data of all surfaces of the dentition and tissue. This eliminates the potential inaccuracies caused by the extrapolation of data.

Mack: Unlike the two systems you mentioned, iTero does not feature an in-practice milling system. So the capital expense with iTero is modest without any limitations on either restorative materials or clinical indications. As such, iTero can serve as a digital front end to any type of restorative system - conventional or CAD/CAM. This includes the current standard of care, porcelain fused to metal. Cadent is positioning iTero as open architecture. This means the digital file also can be sent to in-lab CAM systems, too.

Dr. Dalin: When it comes to investigating new technologies, there is nothing better than to educate dentists in advance. With these technologies, dentists will encounter terms like confocal, triangulation, reflective coatings, stereolithographics, and active wavefront sampling. Can each of you help our readers by providing some simple definitions of terms that dentists soon will be seeing?

Girard: Jeff, in answering your question, I would like to focus on the imaging technology used in the 3M ESPE Intraoral Scanning System. By understanding this digital impressioning, we can bring great value to your readers. Active Wavefront Sampling (AWS) is a new technique for capturing three-dimensional data that enables a 3-D video in motion approach to scanning. This technology was born from research done at MIT. Unlike triangulation and laser methodologies, AWS does not rely on the warping of a laser or light pattern on an object to determine 3-D data. These more traditional 3-D methods suffer from distortion, optical illusion, and are comparatively slow. AWS allows a user to capture 3-D data in a video sequence and model this data in real time. It is highly accurate and extremely fast.

Mack: Providing simple definitions for these concepts is a great idea. Unfortunately, it is not easy to reduce their complexities to a few words but I will attempt to do so. Let me start with the underlying imaging challenges:

• Triangulation: The majority of optical scanning systems are based on some form of triangulation. There are three common elements to all such systems: (1) a light source that (2) illuminates the object, which is positioned at an angle to (3) a detector. This triangulation of light leads to compromised accuracy when scanning two types of surfaces:

curved surfaces because the angle of reflection reduces the viewing area

surfaces that do not reflect light evenly, such as natural dentition vs. amalgam

To cope with this second problem, systems based upon triangulation require dental surfaces to be coated with an opaque, reflective coating. An uneven coating, or environmental changes during scanning - such as saliva, contact with scanner probe or the tongue - might further compromise the accuracy of these systems.

  • Parallel confocal: Confocal is a principle by which light is filtered by passing it through a small pinhole. Only the light reflected from the object at the proper focal distance will pass through the pinhole. Therefore, only those rays that are in focus will return through the filtering device. The iTero system expands upon this concept by simultaneously projecting 100,000 beams of parallel red light rays with each individual scan.

  • Telecentric: We should also add telecentricity to this survey of important imaging concepts. A telecentric system maintains the same field of view, the area being scanned, regardless of distance from the object that is being imaged. As a result, there is no need to compensate for different levels of magnification and no need for the user to hover above the object. To my knowledge, iTero is the only system - on the market or under development - that is not based on triangulation while also being telecentric. As a result, no reflective coating is required. The probe can be placed directly on the surface. This promotes ease of use and patient comfort. The parallel confocal design also promotes exceptional accuracy.
  • Steriolithography: The digital files from these systems are transmitted into CAD systems, then to various CAM production systems. Steriolithography is just one of many additive CAM approaches that build up materials. On the other hand, milling-based CAM systems are subtractive in nature. Digital impressions from iTero can interface with all types of CAD and CAM systems.

Dr. Dalin: How will blood and saliva, or any other clinical conditions, affect images taken by each of your companies’ products?

Girard: Proper tissue management is required to capture an effective impression. For example, the pooling of blood or saliva that could block out critical anatomical features of dentition or tissue needs to be suctioned. What the camera can’t see, it can’t capture.

Mack: As I noted previously, these and other environmental factors can impact the accuracy of triangulation-based systems. Since iTero is based on the parallel confocal method, there is no impact of these conditions during the digital capture process. In fact, the real-time display of digital models calls attention to such issues. This allows the dentist to dry the field as often as needed, and to take additional scans that will enhance the visibility of the prep line and the surrounding tissue.

Dr. Dalin: Think about some of the big advances that have occurred during the history of dentistry: air turbine handpieces, fiber-optic lighting in handpieces, magnification loupes, digital radiography.... These have changed how the practice of dentistry takes place. I think the new technologies of your companies should be placed with some of the biggest and most significant changes that our profession has seeen. What about future possibilities? I can imagine taking a digital impression of my prepared tooth and sending it via e-mail to a milling center, where a zirconium core can be made from the data I provide. In turn, the core is sent on a mounted model to my ceramist on which the final porcelain can be added. We are talking speed, simplicity, and accuracy. Am I expecting too much?

Girard: Your excitement is well founded. While conventional impression materials have certainly improved, the process involved is often difficult for a dentist and laboratory. For a patient, the process has not improved much through the years. The comfort factor for the patient having a digital impression with the 3M ESPE Intraoral Scanning System is significant. Thus far in our field tests, we have experienced an overwhelmingly positive response from patients. Digital dentistry is impacting our lives in a positive manner. It’s not just about convenience, high tech, or the “cool factor.” Digital impressions are expected to improve productivity, reduce chair time by eliminating costly reworks and adjustments, and improve communications between the dentist and patient as well as between the dentist and lab. Digital dentistry also will enable the adoption of new technologies at the laboratory that will improve its productivity, too.

Mack: Since the launch of iTero in June 2006, we have received countless testimonials from dentists and their staffs, dental labs, and - most importantly - patients. In fact, it is quite common for iTero users to report that they have experienced little or no adjustment during seating and also have reduced seating appointment times by 25 to 33 percent because the results are so predictable.

Dr. Dalin: Let’s discuss the economics of this new technology. Obviously, there is going to be a large investment made in hardware. I understand that we will save money on impression trays, impression materials, and tips, and that we also will have some time savings. In addition, you can add goodwill and patients’ happiness from not having to hold an impression in their mouths. What about the costs and benefits?

Girard: Our Brontes Technologies team is excited to be a part of 3M ESPE. After the acquisition, many dentists and lab owners told me that they think 3M is the most trusted company in the dental world. In part, I believe this is because of the company’s diligent, controlled, and well-executed launch of new products and its support for these products after the sale. We are proud to be a part of that tradition. Much of this diligence comes from listening to customers. Being a leader of impression material, 3M ESPE understands that, beyond the “cool factor,” the economics of a product have to work for the patient, dentist, and lab or the product will not be successful. In addition to presenting features and benefits, our team will focus on demonstrating the system’s value proposition and its economic advantages when the system is launched.

Mack: The iTero system involves an upfront investment of $15,000 plus a $3,000 service agreement. This provides a dentist with free software upgrades plus three years of remote diagnostics and “hassle-free” service on the equipment. Typically, the system is purchased with a lease costing less than $500 per month. In addition, there is a $25 per case fee for the dental practice. Most dental practices don’t realize that this essentially offsets the cost of conventional impressions per case once staff labor and retakes are considered. In the vast majority of cases, the lab fee to the dentist is unchanged.

Dr. Dalin: I know each of you has units placed in dental offices around the country. Should we expect to see any published, peer-reviewed, university-based research that will discuss clinical trials?

Girard: 3M ESPE has built a solid reputation for launching high quality and proven products. The process includes: voice of the customer research, key opinion leader feedback, and - most importantly - user validation. Currently, we are working with universities and key opinion leaders in this process. Our testing and validation will be well-documented and published.

Mack: Every week, we are expanding the satisfied user base of iTero dental practices. Prior to commercializing the system in 2006, Cadent conducted three years of clinical testing, completing approximately 1,600 cases from 15 dental practices. A controlled study also was conducted, and is the subject of a forthcoming article in a well-known peer-reviewed journal.

Dr. Dalin: I look forward to seeing more from each of your companies in the coming months. Please keep me informed about the latest on this new technology so that I can keep Dental Economics® readers informed. Before we end this discussion, is there anything else either of you would like to add?

Girard: Thank you for the opportunity to be interviewed. We are living in exciting and dynamic times. With many new technologies appearing for dentists and laboratory owners so quickly, it can create some apprehension and anxiety. As I browse through various dental publications each month, I gasp at how confusing it can be to try to differentiate between the plethora of new CAD/CAM systems, various restorations, and new technologies for dental offices and dental labs. I continue to believe the best approach is to:

  • stay informed
  • don’t make panic purchases
  • do your homework
  • partner with a good dental laboratory and work with reputable dental companies that have a history of supporting a product or technology after you invest in it.
Mack: Thank you for the opportunity to educate your readers about Cadent iTero, which has been extremely well-received in the dental community since its launch. With iTero, we are building the same reputation for reliability and excellence that Cadent OrthoCAD has earned since 2001 as a leader in digital orthodontics. I appreciate your enthusiasm for what this new era in digital impression-taking will bring. The era of digital dentistry has begun and we are pleased to be at the forefront of this new technology.

Editor’s Note: To form your own impression, visit the Cadent Web site at www.cadentitero.com, or contact Cadent Customer Support directly at (800) 577-8767, option 2.

Timothy Mack is executive vice president and general manager, iTero Unit at Cadent, and leads the company’s crown and bridge division. Prior to joining Cadent, he was the vice president and general manager of DENTSPLY Ceramco and held key managerial positions in the Medical Imaging Division at Eastman Kodak.

In July 2005, Mike Girard joined the Brontes Technologies team, which was acquired by 3M in October 2006. Brontes Technologies soon will launch a revolutionary scanning technology. Girard has more than 30 years of experience in the dental field. He attained licensure as a registered dental technologist in 1975.

Jeffrey B. Dalin, DDS, FACD, FAGD, FICD, practices general dentistry in St. Louis. He is the editor of St. Louis Dentistry magazine, and spokesman and critical-issue-response-team chairman for the Greater St. Louis Dental Society. He is a co-founder of the Give Kids A Smile program. Contact him at [email protected].

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