The Current State of Digital Impression Systems in Dentistry
An overview of digital systems for general practitioners
Chad C. Duplantis, DDS
Successful indirect dentistry depends upon multiple factors. Clinicians often concentrate on preparation design, impression materials, restorative materials, luting selections, and, of course, the cost associated with all of these steps. Each of these factors plays a role in the success or failure of the final restoration and the patient’s overall dental experience. Of all of these factors, the one that patients seem to remember—and complain about—the most is the impression, including everything from the material to the technique and their overall experience of it. What if a clinician could improve that technique to such a degree that it was not only incredibly accurate, but it would also substantially improve the patient’s experience? What if a final restoration or other oral device could be produced that is every bit as accurate as a dental impression?
A Brief History of CAD/CAM Dentistry
CAD/CAM dentistry has been in use in dental practice for almost 30 years. Duret began the digital revolution in 1971.1 However, Mörmann was the first to bring the concept into clinical practice with the CEREC 1 in 1987.2 The original system, which was not very user-friendly, was limited to inlays and onlays. Sirona (www.sironausa.com) developed CEREC and had the market cornered for many years, and was a true pioneer in the industry. CEREC had no competition until several years later, when E4D Technologies’ (www.e4d.com) chairside CAD/CAM system was introduced in 2007.3 Over the past several years, the landscape has become more diverse as other dental manufacturers have introduced their digital products. The choices are so numerous that it can be overwhelming for the dentist when entering this facet of dentistry.
CAD/CAM dentistry has evolved a great deal since the first CEREC was introduced, and it is the changes in the more recent years that have influenced the profession in powerful ways. The concept of CAD/CAM dentistry used to be marketed as scanning, designing, and milling of restorations all in one visit. This concept limited the materials available for the final restoration, and it also virtually eliminated the dental laboratory from the equation. Over the past several years, the mills have become more of an option, and the scanner as the driving force of CAD/CAM dentistry has been re-established. With laboratories becoming more involved again, the material choices available have expanded, as have the dental indications. The systems that are available today are not only capable of producing inlays, onlays, and crowns, they are now capable of producing digital impressions that can be used to fabricate almost any restoration or product that a traditional dental impression can. One of the experts in the field, Dr. Daniel Wismeijer, sums up the new age of digital dentistry with the following profound statement: “Digital dentistryis developing to a world where patients and in mouth products are analog, but everything in between becomes digital.”4
Accuracy of the Current Digital Techniques
The scanners of today demonstrate an incredible level of accuracy. The stereolithography (.STL) models produced from the scans have proven to be an accurate replacement to the traditional plaster models with minimal distortive potential.6 These models are made of a hard resin that are polymerized by ultraviolet light. It is an additive technique that creates an incredibly accurate model based upon the .STL file generated by the scanner used.7 These models do not chip or abrade. They provide the dentist with a model that can be used repeatedly with no distortion.
With regard to the restorations produced,the process has also proven to be incredibly accurate. The anatomy in the restorations was once an issue, but this has improved greatly over the past 30 years. The initial concept required the anatomy to be ground in by a handpiece.1 Occlusal anatomy is no longer an issue, nor is the marginal or internal fit. Recent studies have concluded that the marginal of digitally manufactured crowns is superior to that of conventionally made crowns. The internal fit of digitally produced restorations has been proven to be as good, if not better, than crowns fabricated using conventional techniques.8-10
It is of importance to note the speed at which the digital impression process takes place. In considering the total amount of time to acquire a scanned impression versus a conventional impression, digital impressioning is considerably faster. For certain impressions, digital techniques have been proven to be up to 23 minutes faster.11
Open vs. Closed Architecture
Digital impression systems operate under distinct categories, open and closed architecture.These two basic terms are used to define the manner in which the impressioning device communicates with mills and laboratories.
An open system generates a .STL file. This is a file format mainly understood in the CAD industry. The files generated are easily shared once they are produced. The format is easily received by most laboratories, and can be integrated into multiple software systems for design and milling. The .STL files are also able to communicate with many available mills for in-office use. The use of an open system creates numerous opportunities for restoration design and fabrication, including orthodontics.
A closed system also generates a .STL file but it can only be viewed or read by the specific closed software. The file transfer workflow in closed systems is usually proprietary in nature. Although there are many restorative and orthodontic options in a closed system, the communication options are not as numerous as they are in an open system. CEREC is an example of a closed-architecture system. CEREC scanners communicate with CEREC mills and laboratories that have CEREC in the lab.12
The Systems
The marketplace is becoming inundated withdigital technology. Improvements to bothhardware and software are under constantdevelopment, resulting in better placement inthe dental office. It can be a daunting task to compare the systems that are available today.This article will only look at the top selling systems that are available today.13
3M™ True Definition Scanner
In 2007, 3M (www.3m.com) introduced the Lava™ Chairside Oral Scanner C.O.S., following acquisition of the technology from Brontes Technologies. The system had many advantages but also had some disadvantages. Although the product had its merits, 3M went back to the drawing board to make some much-needed improvements, and the resulting 3M™ True Definition Scanner launched in late 2012. The new and improved system is extremely economical, and has several features that make this a great product to consider. The system uses 3D-in-motion video technology to acquire the image; in other words, the data is captured and modeled in real time. The system is entirely open, meaning that it can transfer standard .STL files to a device used to manufacture a restoration or model that is set up to receive these files. Being an open system, it can be used as an impressioning device for a multitude of restorations, such as crowns, bridges, inlays, onlays, partial dentures, full dentures, models, and orthodontic appliances. The system also communicates with several mills for indirect chairside restorations. The system is all contained in a portable device that easily transfers between operatories. The drawback, as seen by many, is that the system does require powder to capture an image. This is a very light dusting (almost a mist) of powder applied to the surfaces of the intraoral structures to be captured. Studies have proven that powder increases accuracy compared to non-coated surfaces.14
PlanScan
The PlanScan, by Planmeca (http://planmecacadcam.com), is also an opensystem, and its files are also accepted by many dental laboratories. The system uses a blue laser technology to acquire a video image. The PlanScan communicates with the PlanMill 40, which is Planmeca’s proprietary option. The system does not require powder but does have available a liquid opaquing medium for highly reflective surfaces that is considered to be very accurate. The image produced by the scanner is represented in color; however, it is not representative of the dentition. The system is capable of producing many restorations. At this point in time, however, there is no associated orthodontic workflow. A nice advantage of this scanner is the ability to erase and rescan a portion of the scan. The system is available as a laptop-based system, so it is portable.
TRIOS®
Another open system with incredible accuracyis the TRIOS by 3Shape (www.3shapedental.com). Multiple restorative and implant workflows are available, as well as laboratory support. At this point in time, there is no orthodontic workflow. The image is acquired by a laser high-speed line scan, and it is displayed in true color. No powder is required. The scanner and wand are contained on a mobile device, or they can be used with laptop capability. A chairside option is available through thePlanMill 40 from Planmeca. One of the nice features of this system is the ability to color match. One of the main disadvantages of this system is the price. This is the most expensive scanner on the market.
iTero® and iTero® Element™
Developed by Align Technologies (www.itero.com), the iTero is the first generation of this open-system scanner. The iTero Element is the newest version. Multiple restorative, implant, and orthodontic workflows are available. The incredibly accurate image is acquired by a laser confocal point and stitch method, and displayed in pseudo-color. The entire system is on a mobile cart. The system will communicate with the iOs TS150 mill for a chairside option. The new Element system has a patented dual-aperture lens system, which enhances the speed and quality of the images produced. Neither the original or the Element system provides a true color. The iTero Element is not yet available for restorative dentistry, but it is available for use in orthodontics.
Carestream CS3500
The Carestream CS 3500 (www.carestreamdental.com) is a relative newcomer to the market. An open system, it uses a laser point and stitch technology for image acquisition. This system requires a point-and-click by the operator to obtain the image. The system generates a “life-like” image in pseudo-color. Once again, with this being an open system, the restorative and implant restorative options are plentiful. The system can be used for orthodontic planning, but there is no orthodontic workflow at this point in time.
CEREC Omnicam
CEREC (www.cereconline.com) has several scanners available, and is a closed system.Please note, being a closed system does not imply that there are fewer restorative choices. There are several restorative choices available; however, in order to use a laboratory, they must have CEREC inLab. There are several mills available that communicate with the CEREC Omnicam. The Omnicam has the most capabilities of the CEREC scanners. Powder is not used to acquire the image for this system. The scanner produces an image in pseudo-color. The image is acquired via a high-speed confocal point-and-stitch method. The system has multiple implant and restorative workflows. There are also a couple of orthodontic workflows available as well. The main disadvantages to this system are the fact that it is closed and that it is rather costly.
Incorporating Digital Scanners Into the Practice
The Patient
The most important factor is the effect on the patient. The patient should always be the clinician’s top concern. The ill-received perception of a clinician’s technique could have a negative impact on that clinician’s success. Recent studies have shown that a patient would choose a digital impression technique over a conventional impression technique.15
The Laboratory
The switch to digital impressioning should not be made to eliminate the lab bill. The dental laboratory is more capable of fabricating certain restorations. Although it may be impossible to eliminate the lab bill entirely, it can be greatly reduced. Many labs have offered incentives to practitioners that are using digital impressioning devices. A common misconception with regard to the dental lab is that all restorations must be CAD-produced. The impressions and models created from open systems make it possible for any type of restoration to be produced. Digital impressioning should strengthen the relationship with the laboratory. In addition to the reduced remakes, the laboratory will benefit from the lack of distortive potential in transporting the models. The aforementioned benefits should also lead to reduced time in seating the restoration.16
The Staff
Make sure that the staff is committed to change. One of the biggest failures of incorporating technology is the resistance to learn. While there is a learning curve associated with each of these scanners and it is not an exact science, all staff members should be fully competent after completing 20 scans.
The Cost
Another factor to consider is the cost of the system. When one looks at costs, one needs to look beyond the initial costs, to other factors such as monthly usage fees, software upgrades, and warranties. The least expensive and the most expensive systems each have different capabilities, and therefore will also have different fees for usage and upgrades. Cost should be weighed, but is certainly not the only factor to consider.
Same-Day Dentistry
A great feature of any of these systems is the ability to integrate them into clinical practice with minimal up front investment. Although initially a dentist may not want to mill, it is recommended that he or she buy a scanner with milling capability. This will eliminate the need to purchase a new scanner later on if milling ever becomes desired.
The Capabilities
Any practitioner who is considering going digital will want to consider the capabilities and contraindications of the various systems that are available. None of the systems on the market can accurately scan through or around blood, tissue, or saliva. In other words, retraction and proper preparation isolation is a must.17 The impressioning technique is still very similar to that of a traditional impressioning technique; the principles are the same either way. The clinician must play with the available scanners and get the feel for what will work best in his or her practice.
Conclusion
With all of the factors that need to be considered before making the leap into digital dentistry, a clinician must ask, “Why make a change?” What is it that is intriguing enough to look into digital dentistry? Any clinician that is having success with his or her current techniques may not need to look further into digital impressioning.
The digital landscape of dentistry is changing on a daily basis. The “middle man” in dentistry has recently become an intangible innovation. Diagnosis and treatment planning still play the most important role in the profession of dentistry, but scanners have become a fascinating tool to produce an extremely accurate dental restoration by non-conventional means. Clinicians need to stay abreast of the changes to provide the patient with the most advanced form of treatment available.
Disclosure
Dr. Duplantis reports no conflicts of interest with the material presented herein.
References
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About the Author
Chad C. Duplantis, DDS
Private Practice
Fort Worth, Texas
