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Mupparapu M. Intraoral Scanning and Digital Impression Techniques in Dentistry. J Orofac Sci [serial online] 2019 [cited 2019 Aug 13];11:1-2. Available from: http://www.jofs.in/text.asp?2019/11/1/1/264189
Based on the available evidence on the introduction of intraoral scanning (IOS) techniques in the dental profession dating back to the early 1980s, it is fair to say now that the technology is more mature than ever. IOS has become integral part of many restorative, implantology, and orthodontic procedures for capturing surface details of teeth for fabrication of inlays, onlays, or crowns (both laboratory-based and chair-side) as well as applications in implantology for fabrication of custom abutments or screw-retained crowns and surgical guides for accurate placement of root form implants. In orthodontics, the intraoral scanners are being used for digital storage and on-demand model production in 3D printers, digital impressions, 3D aligner treatment plans, to name but a few. Many of these digital impression techniques are drawn into lab-based services for fabrication of restorations and hence the companies that offer these services have invested in the development of the digital impression systems via scanners as well as in the development of logistics for digital transmissions and fabrication of restorations, crowns, and surface coverages used for aligning teeth.
The technologies differ in the acquisition of images and their storage, although the end products are quite similar. For example, the CEREC system (Serona, Bensheim, Germany) is designed in 1987 with the concept of “triangulation of light.” Since surfaces with uneven light dispersion reduce the accuracy of the scans, opaque power coating of titanium dioxide is recommended for the scanning. One of the latest generations of CEREC scanners called CEREC ACBluecam uses LED blue diode as its light source.
Another system called the LAVA C.O.S. system (3M ESPE, Seefeld, Germany) was introduced to clinical dentistry in 2008 that works using the principle of active wavefront sampling based on a single-lens camera. Three sensors capture data simultaneously, creating more than 2400 data sets to increase the surface accuracy. This system has the smallest scanner tip in the market with 13.2 mm width. This system also needs opaque power coating.
The iTero system (Cadent Inc., New Jersey) came to the market in 2007. This system captures images based on laser and optical scanning using the principle of parallel confocal imaging. The iTero is an open software system in the treatment of crowns, FPDs, implants, aligners, and retainers. The system exports digital image files in .STL format that can be shared by other labs equipped with CAD/CAM systems.
The E4D system (D4D Technologies, LLC, Richardson, TX) uses the principle of optical coherence tomography and confocal microscopy. Using red laser as a light source and micromirrors to vibrate 20,000 cycles per second, it creates a digital 3D impression that is also interactive. This system is power free.
Finally, the TRIOS system (3Shape, Copenhagen, Denmark) introduced in 2011 uses the principle of ultrafast optical sectioning and confocal microscopy. Since it acquires up to 3000 images per second, movement artifacts are reduced or minimized. Like the iTero and E4D, this is also a power-free system.
In a study conducted by Syrek et al., the authors concluded that the ceramic crowns fabricated from a digital impression had a better fit than those made from conventional impressions.
Overall, optical impressions reduced patient discomfort, are time-effective, simplify clinical protocols, and allow better communication with the lab and patients. Although the literature supports the use of intraoral scanners for accurate capture of dental topography and fabrication of inlays, onlays, coping, frameworks, single crowns and fixed partial dentures, smile designing, post and core fabrication as well as removable of partial prosthesis and obturators, it does not support the use of IOS in long-span restorations with natural teeth or implants as yet. The utilization of IOS in implant dentistry is also well documented and use of IOS orthodontics for fabrication of aligners and custom-made devices is on the rise. Total elimination of traditional impression techniques is a good possibility in the near future.