title: Precision of a CAD/CAM technique for the production of zirconium dioxide copings.
abstract: OBJECTIVE
  The precision of a computer-aided design/manufacturing (CAD/CAM) system to manufacture zirconium dioxide copings with a predetermined internal space was investigated.
  
  
  METHODS
  Two master models were produced in acrylic resin. One was directly scanned by the Decim Reader. The Decim Producer then manufactured 10 copings from prefabricated zirconium dioxide blocks. Five copings were prepared, aiming for an internal space to the master of 45 microm. The other five copings were prepared for an internal space of 90 microm. The second test model was used to try in the copings produced. The obtained internal space of the ceramic copings was evaluated by separate measurements of the master models and inner surfaces of the copings. The master models were measured at predetermined points with an optical instrument. The zirconium dioxide copings were measured with a contact instrument at the corresponding sites measured in the masters.
  
  
  RESULTS
  The first group of copings had a mean internal space to the scanned master of 41 microm and of 53 microm to the try-in master. In general, the internal space along the axial walls of the masters was smaller than that along the occlusal walls. The second group had a mean internal space of 82 microm to the scanned master and of 90 microm to the try-in master.
  
  
  CONCLUSIONS
  The aimed-for internal space of the copings was achieved by the manufacturer. The CAD/CAM technique tested provided high precision in the manufacture of zirconium dioxide copings.
authors.affiliation: Department of Prosthetic Dentistry/Dental Materials Science, Faculty of Odontology, The Sahlgrenska Academy at Göteborg University, Sweden. pierluigi.coli@odontologi.gu.se
authors.forename: Pierluigi
authors.initials: P
authors.lastname: Coli
authors.forename: Stig
authors.initials: S
authors.lastname: Karlsson
mesh_terms: D017076:Computer-Aided Design; D003442:Crowns; D000044:Dental Abutments; D003776:Dental Porcelain; D017267:Dental Prosthesis Design; D006801:Humans; D008422:Materials Testing; D016876:Metal Ceramic Alloys; D015203:Reproducibility of Results; D015040:Zirconium
chemical_list: C453860:Denzir; D016876:Metal Ceramic Alloys; D003776:Dental Porcelain; D015040:Zirconium; C028541:zirconium oxide