CAD/CAM and Digital Impressions

Currently, two genres of CAD/CAM systems exist. One is used only in-office, while the other genre is a combination of in-office scanning and image transmission and milling of restorations or pouring of models in the laboratory. All systems start with scanning of the preparation, the method depending on the specific system. CAD/CAM systems have developed considerably, offering accuracy and more options than previously. It can be envisioned that CAD/CAM technology developments will continue to offer dentistry more options for its use, including further CAD/CAM integration of procedures and imaging enhancements. Introduction There are two current genres of in-office CAD systems. One genre is a complete system where the practitioner can scan preparations, design restorations and manufacture a finished product in the office, in one visit. The other system concentrates on the scanning/digital impression and the practitioner then exports that information to a traditional dental lab or to a designated CAD/CAM laboratory for restoration or substructure fabrication. Both genres offer benefits compared to traditional methods and a number of systems are available for the practitioner to choose from, each using different technology to achieve the end results.1,2 Image Acquisition Each system uses a different method to acquire the images. The first system introduced was the CEREC 1 in 1986. The CEREC 1, 2 (1994) and 3 (2000) systems (Sirona Dental) have all used a still camera to take multiple pictures that are stitched together with software. The E4D (D4D TECH) takes several images, using a red light laser to reflect off of the tooth structure and only requires the use of powder in some limited circumstances. The application of powder to the tooth is quick and simple, taking only seconds, and the powder is easily removed afterwards with air and water. The iTero system uses a camera that takes several views (stills), and uses a strobe effect as well as a small probe that touches the tooth to give an optimal focal length; this system does not require the use of powder. The LAVA Chairside Oral Scanner (LAVA COS, 3M ESPE) takes a completely different approach using a continuous video stream of the teeth. CEREC and LAVA currently require the use of powder for the cameras to register the topography. Other scanner systems are also available. Figure 1. CAD/CAM systems Each system uses a system-specific handheld device to scan the site (Figure 2). Figure 2. CEREC (upper image) and LAVA COS (lower image) An Overview of CAD/CAM and Digital Impressions by Paul Feuerstein, DMD