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The primary cutting-edge technology that Girard-Sebestyen feels “will most certainly drive the transition to digital,” will be the latest intraoral scanning systems, which allow the clinician to send a digital impression to the lab. Digital impression systems, such as Cadent’s iTero and the 3M C.O.S. Chairside Oral System, incorporate a maneuverable wand-like intraoral scanner employed by the clinician to capture data of the prepped tooth site along with adjacent and opposing dentition. The lab receives the digital impression data electronically, and the system software generates a 3D virtual model for CAD work.

Dentists using Sirona’s CEREC chairside intraoral scanner for in-office designing and milling of all-ceramic inlays/onlays and crowns now have the option of sending the scan data to an inLab-equipped dental laboratory through the CEREC Connect Web portal. Ragle, who has been working with the new software system, said the dentist can send intraoral scans to the laboratory for the design and milling of single units followed by custom staining and glazing by the experienced technician as well as for the fabrication of bridges that can not be milled by the chairside unit.

Digital intraoral impression systems offer many benefits to the dentist, chairside staff, and

Digital by Design

The clean, modern approach to the traditional concept of the dental laboratory as conceived by Quantum Technologies includes the incorporation of high-tech digital impression-taking, CAD/CAM, and 3D waxing systems to replace many technician-based tasks.

patient as well as the laboratory technician. Gone would be the mess, gagging, time, and expense involved with taking physical impressions of the patient in the chair. Also eliminated would be the multitude of material problems—shrinkage, expansion, and distortion of the impression material; pouring and set-up of the stone model; infection control concerns; shipping and handling of the trays; and the chipping of models—that could cause problems with the manufacture of the restoration and eventually lead to costly and embarrassing remakes.

“Not taking an impression is a really big incentive for a dentist to convert to digital impressions,” Stroh said.

However, Dr. Michael DiTolla, Director of Clinical Research and Education at Glidewell Laboratories, cautioned, “I’m not sure digital impressions, at least in the state that they’re in now... are a product for the masses.” He added that digital impression-taking requires even more meticulous preparation of the margins than traditional impressions; there can be no blood present on the tissue in the area of the scan. If doctors already take mediocre, undefined traditional impressions, then “they’re going to take worse impressions with the digital technology.”

After the tooth has been properly prepared, and the digital impression has been captured, the electronic data is sent directly to the laboratory, where it is incorporated into some form of CAD/CAM process.

For working with physical tray-based impressions, technologies like the Optimet scanner being tested by Glidewell work as a middle ground, digitizing the impression into a virtual model that can be used in similar fashion as the data from a digital intraoral impression. This process would allow the dentist to take a traditional impression, then scan the physical form, and send the digital data file to the laboratory, saving shipping expenses and time, and eliminating many of the problems associated with asepsis of mailed tray impressions.

The iTero digital impression paradigm allows the laboratory technician to use the virtual model to design a substructure to be milled, laser-sintered, or 3D-printed on a CAM component, even while Cadent mills then ships the resin model. By the time this physical model gets to the lab, the crown could be fabricated from the data already received and used in CAD/CAM processes.

For 3M ESPE, the answer to the need for a physical model created from an intraoral scan taken by the C.O.S. digital impression system resides in 3D printing. 3M has partnered with 3D Systems for model production via the company’s Viper Pro SLA rapid manufacturing platform using 3D Systems’ proprietary Acura SL material.

As virtual design and fabrication move forward, the lack of a working model, however, could be a sticking point for some technicians who prefer the tactile sensation of holding a model while they create the restoration and check the fit of the work. But, Girard-Sebestyen said, “The models may not even be necessary as we find ways to do reverse engineer virtual quality control.”