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ePaper created 2017-02-21, 16:08:16 | version 1.38.0
literature review _ CAD/CAM material and systems Different manufacturers are using zirconia as one of their main materials such as: Ceramill Zolid (Amann Girbach), Prettau (Zirkonzahn), Cer- con (DENTSPLY), BruxZir (Glidewell Laboratories), IPS ZirCAD (Ivoclar Vivadent), Zenostar (Ivoclar Vivadent), inCoris ZI (Sirona Dental), VITA In-Ce- ram YZ (Vident), among others. Companies have introduced materials that are in combination with zirconia to improve its properties in different clin- ical situations. Lava Plus, for example, is a combi- nation of zirconia and a nano-ceramic. _CAD/CAM systems A number of different manufacturers are pro- viding CAD/CAM systems that generally consist of a scanner, design computer and a milling machine or 3-D printer. Laboratories are able to receive dig- ital impression files from dentists or use a scanner to create digital models that are used for resto- rations designing or CAD. Dental scanners vary in speed and accuracy. Milling machines vary in size, speed, axes, and also in which restorative materi- als can be milled; in this category milling machines could be classified as wet or dry depending if the materials require irrigation. The development of dental CAD/CAM systems occurred around 1980 with the introduction of the Sopha system devel- oped by Dr Duret. A few years after that event, Dr Mormann and the electrical engineer Marco Brandestini developed 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 dedicated to this field has continued and has exponentially increased in the last de- cade.14 CEREC systems has evolved into CEREC Blue- cam scanner; accuracies as close as 17 microns 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 mar- ginal fit of CAD/CAM restorations fabricated with CEREC Bluecam, they compared lithium disilicate single unit restorations to heat-pressed resto- rations 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 Dental) was designed for dental laboratories for a wide range of dental capabilities that can be combined with third party systems. With this software, the dental technician is able to scan their own mod- els using Sirona inEos X5 (Sirona Dental) scanner and design the restoration; once this process is completed, the file can be sent to a remote mill- ing machine or a milling centre for fabrication in a wide range of materials. The Procera system, introduced in 1994, was the first system to pro- vide fabrication of a restoration using a network connection. According to research data the aver- age 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 semifinished crowns to be delivered to dental lab- oratories 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 developed a similar system called the Zirkograph in 2003, which was able to copy-mill zirconia prosthesis and resto- Fig. 4_Full arch implant supported prosthesis milled from a partially sintered sintered (green state) zirconia puck. Fig. 5_STL file of an intraoral scan. Fig. 4 Fig. 5 19 dentistry1_2017cosmetic