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CAD/CAM - international magazine of digital dentistry, Italian Edition, No.2, 2017

literature review _ CAD/CAM material and systems properties are: high mechanical strength, frac- ture toughness, radiopacity for marginal integ- rity evaluation, and relatively high aesthetics.13–14 Different manufacturers are using zirconia as one of their main materials such as: Ceramill Zol- id (Amann Girbach), Prettau (Zirkonzahn), Cercon (DENTSPLY), BruxZir (Glidewell Laboratories), IPS ZirCAD (Ivoclar Vivadent), Zenostar (Ivoclar Viva- dent), inCoris ZI (Sirona Dental), VITA In-Ceram YZ (Vident), among others. Companies have in- troduced materials that are in combination with zirconia to improve its properties in different clinical situations. Lava Plus, for example, is a combination of zirconia and a nano-ceramic. for a single tooth have been reported by authors using this system. Recently CEREC Omnicam was introduced offering true colour digital impres- sions without the need of a contrast medium. In a recent study by Neves et al. (2013) on the marginal fit of CAD/CAM restorations fabricat- ed with CEREC Bluecam, they compared lithium disilicate single unit restorations to heat-pressed restorations and 83.8 percent of the specimens had a vertical gap measurement with less or at least 75 microns.15 The CEREC InLab CAD software (Sirona Den- tal) was designed for dental laboratories for a wide range of dental capabilities that can be Fig. 4_Full arch implant supported prosthesis milled from a partially sintered (green state) zirconia puck. Fig. 5_STL file of an intraoral scan. Fig. 4 Fig. 5 _CAD/CAM systems A number of different manufacturers are providing CAD/CAM systems that generally con- sist of a scanner, design computer and a milling machine or 3-D printer. Laboratories are able to receive digital impression files from dentists or use a scanner to create digital models that are used for restorations designing or CAD. Dental scanners vary in speed and accuracy. Milling ma- chines vary in size, speed, axes, and also in which restorative materials can be milled; in this catego- ry milling machines could be classified as wet or dry depending if the materials require irrigation. The development of dental CAD/CAM sys- tems occurred around 1980 with the introduc- tion of the Sopha system developed by Dr Duret. A few years after that event, Dr Mormann and the electrical engineer Marco Brandestini devel- oped the CEREC-1 system in 1983, the first full digital dental system created to allow dentists to design and fabricate in-office restorations. Since then, the continuous evolution of systems ded- icated to this field has continued and has expo- nentially increased in the last decade.14 CEREC systems has evolved into CEREC Blue- cam scanner; accuracies as close as 17 microns combined with third party systems. With this software, the dental technician is able to scan their own models using Sirona inEos X5 (Sirona Dental) scanner and design the restoration; once this process is completed, the file can be sent to a remote milling machine or a milling centre for fabrication in a wide range of materials. The Procera system, introduced in 1994, was the first system to provide fabrication of a resto- ration using a network connection. According to research data the average ranges of marginal fit of this restorations are from 54 to 64 microns.20 A computer integrated crown reconstruction system (CICERO) introduced by Denison et al. in 1999 included a rapid custom fabrication of high-strength alumina coping and semi- finished crowns to be delivered to dental laboratories for porcelain layering and finishing.15 Another system that was developed years ago was the Celay system, which fabricated feldpathic restorations through a copy-milling process. The system duplicated an acrylic resin pattern replica of a restoration. Zirkonzahn de- veloped a similar system called the Zirkograph in 2003, which was able to copy-mill zirconia pros- thesis and restorations out of a replica of the restoration. Some years after, the Cercon system 2_2017 19