July/August 2010, Volume 6, Issue 7
Published by AEGIS Communications
The Revolution in Digital Impressioning
Nathan S. Birnbaum, DDS
In only the past few years, the revolution in digital impressioning for restorative dentistry that began in 1985 with Sirona’s CEREC has progressed exponentially, with marked advances in the number of available devices, their accuracy, indications for their application, their ease of use, synchronization with laboratory systems, and the number of dentists and laboratories worldwide utilizing the technology. Two years ago, there were four major systems available for restorative dentistry: CAD/CAM devices such as Sirona’s CEREC 3D and D4D’s E4D, and dedicated impressioning instruments, such as Cadent’s iTero and 3M ESPE’s Lava C.O.S.
Today—in addition to the CEREC AC Powered by Bluecam and inLab; the E4D Dentist, Labworks, and Studio; the iTero; and the Lava C.O.S.—newer systems have emerged, including IOS Technologies’ FastScan; Densys3D’s Solution; and Hint-ELs/Fraunhofer’s directScan.
The CEREC and E4D systems began as dental office-based CAD/CAM systems, in which the intraoral capture of data could be converted into a milled definitive restoration in a single visit. The eventual inclusion in both systems of laboratory software, hardware, and communication programs between the dental office and laboratory was a tacit acknowledgement that not all dentists are able or willing to devote the extra time and effort needed to design, mill, and characterize restorations.
The iTero and Lava C.O.S. systems were solely intended from the outset to provide data to a facility that could convert the data into highly accurate CAD/CAM milled or stereolithically printed articulated resin models which, in turn, would be sent to the laboratory of the dentist’s choice.
In addition to the CEREC and E4D laboratory systems, a number of other companies have entered this field of creating working models either from dentist-submitted scan data or digital scans made in the laboratory from dentist-submitted impressions or models poured from those impressions. These laboratory systems include, among others, Zahn’s Dental Wings, Maestro 3D’s Dental Scanner, and 3Shape’s D700 Adaptive Impression Scanner.
Digital impressions have been used successfully for a number of years in orthodontics, as well, including Cadent’s IOC/OrthoCad, DENTSPLY/GAC’s OrthoPlex, Stratos/Orametrix’s SureSmile, and EMS’ RapidForm.
Indications for the type of restorations that can be made from digital impressions from the various systems cited include inlays, onlays, crowns, fixed bridges and even mouthguards, occlusal guards, and orthodontic appliances. Research is currently underway by several companies to enable the fabrication of full and partial dentures, as well as implant restorations, from digital scans.
In a June 2009 survey conducted by Dental Products Report, more than 16% of general dentists claimed to have some type of digital impressioning device in their practices. That number has increased significantly since then. In fact, Lee Culp, CDT, had predicted in late 2007 that, “within five years, most dentists will be taking digital impressions.”1
The integration of an impressioning system into a dental practice, while it is a quantum leap forward technologically, need not be problematical. The site at which the dentist wishes to take a digital impression is prepared in much the same way as for an elastomeric impression.
Proper tooth preparation and tissue retraction are essential and identical for both modalities. Some impressioning systems require that the sites being scanned first be dusted with a coating of anti-reflective titanium dioxide, while others only require the sites to be isolated and dried. The optical scan of the operative and opposing sites, along with an occlusal registration scan, can usually be achieved in less time than it takes to obtain elastomeric impressions and a conventional bite registration.
One of the most valuable advantages of digital impressions is that they give the dentist the ability to observe a magnified image of the tooth preparation, in some systems even in 3D. Not only does this allow the dentist to hone his or her skills, but also enables correction of problem areas prior to completing the scan. With elastomeric impressions, such imperfections are only found after the impression is taken, and often retaken, which is costly in terms of materials and, especially, time.
At first glance, the learning curve may appear difficult, as digital impressions present a paradigm shift away from the dentist’s comfort zone. Fortunately, most of the systems’ manufacturers have created outstanding learning and assistance programs ranging from a few days of intensive training for dentists and team members at the company’s facility, to trainers helping dentists in hands-on sessions in the dentist’s own office; from courses conducted at many major dental meetings, to online tutorials and courses and service through telephone help lines. Companies have made facilitating the integration of digital impressioning devices into the dentist’s practice a priority.
With recent advances in the quality of digital impressioning systems for the dental office and the pervasiveness of the digital platform in the dental laboratory space, the dental impressioning to finished restoration process is becoming ever more streamlined, thereby improving dentist-technician communication. Transmitted impression data can be viewed and analyzed simultaneously in real time by both the dentist and technician while the patient is still seated in the operatory. Digital impressions have fewer problems than elastomeric impressions in terms of impression distortion, resulting in better marginal accuracy and fewer remakes. The finished restorations also have more precise interproximal and occlusal contacts, which saves time in seating restorations.
From the patient’s perspective, digital impressions eliminate gagging on foul-smelling and tasting goop. The patient also views the dentist as being more cutting-edge, a perception that is often shared with the patient’s friends and colleagues. The dentist and staff also benefit by having to spend less time in clean-up following the impression appointment (ie, no sterilization of impressions nor cleaning of impression guns and syringes). Eliminating elastomeric materials is more ecologically sound, eliminates cross-contamination zones, and saves the office the added expense of associated disposable goods.
The bottom line is important to all dental offices. Although much expense is spared in saving time and the cost of materials, the biggest obstacle to dentists has been the cost of digital impressioning systems themselves, that of submitting data, and of the production of resin models. Companies are working hard to bring down all of those costs.
One company, Clon3D, will be launching a new business model in September whereby dental laboratories lease out the company’s scanner to dentists for a monthly fee. The scanner, which can be attached to any computer with a USB cable, and the accompanying software can convert scan data into a clean, usable STL (ie, a format used by stereolithography software to generate information needed to produce 3-D models on stereolithography machines) file that can be transmitted to any laboratory to create an accurate working model.
The digital impressioning revolution has been underway for many years. It is clearly here to stay.
1. Culp L. Lecture. New England Academy of Cosmetic Dentistry. October 2007; Boston, MA.