title: Three-dimensional accuracy of CAD/CAM titanium and ceramic superstructures for implant abutments using spiral scan microtomography.
abstract: OBJECTIVE
  To introduce a new three-dimensional (3D) method of evaluating the fit of implant superstructures made using computer-aided design/computer-assisted manufacture (CAD/CAM) technology and conventional casting and to determine which biomaterial would produce optimal fit for the long-term clinical longevity of dental implant restorations.
  
  
  METHODS
  Five groups of materials were used to make 50 copings (n = 10) using CAD/CAM technology for titanium, partially sintered zirconia, fully sintered zirconia, and leucite-reinforced glass-ceramic materials and a conventional casting technique for the nickel-chromium group. The vertical marginal gap was measured at 16 equidistant points using a traveling microscope and compared with the 3D spatial gap values obtained by using spiral scan microtomography. Multivariate analysis of variance and Tukey post hoc tests were used for statistical analysis.
  
  
  RESULTS
  The vertical marginal gap width ranged from 13.21 to 75.26 μm for the CAD/CAM groups and 64.89 to 115.27 μm for the conventionally casted group. The spatial gap ranged from 0.22 to 0.67 mm3 for CAD/CAM groups and 0.75 to 0.89 mm3 for the conventionally casted group. The highest accuracy of fit was observed in the titanium group, followed by the leucite-reinforced glass-ceramic, partially sintered zirconia, fully sintered zirconia, and nickel-chromium groups.
  
  
  CONCLUSIONS
  When used in combination with the CAD/CAM technique, titanium produces the most accurate implant superstructure. Spiral scan microtomography can be used to measure the accuracy of fit of dental implant superstructures and restorations as it provides a 3D measurement with less chance of errors compared with conventional methods of measurement.
authors.forename: Rahul
authors.initials: R
authors.lastname: Prasad
authors.forename: Abdulaziz Abdullah
authors.initials: AA
authors.lastname: Al-Kheraif
mesh_terms: D002516:Ceramics; D002858:Chromium Alloys; D017076:Computer-Aided Design; D000044:Dental Abutments; D003735:Dental Casting Technique; D015921:Dental Implants; D003776:Dental Porcelain / Q000737:chemistry; D017267:Dental Prosthesis Design; D061827:Dimensional Measurement Accuracy; D021621:Imaging, Three-Dimensional; D015999:Multivariate Analysis; D014025:Titanium; D036542:Tomography, Spiral Computed; D055114:X-Ray Microtomography; D015019:Yttrium; D015040:Zirconium
chemical_list: D002858:Chromium Alloys; D015921:Dental Implants; C499362:yttria stabilized tetragonal zirconia; D003776:Dental Porcelain; D015019:Yttrium; C023506:Glass ceramics; D015040:Zirconium; D014025:Titanium