title: Precision of fit of implant-supported screw-retained 10-unit computer-aided-designed and computer-aided-manufactured frameworks made from zirconium dioxide and titanium: an in vitro study.
abstract: OBJECTIVE
  To analyze the precision of fit of implant-supported screw-retained computer-aided-designed and computer-aided-manufactured (CAD/CAM) zirconium dioxide (ZrO) frameworks.
  
  
  METHODS
  Computer-aided-designed and computer-aided-manufactured ZrO frameworks (NobelProcera) for a screw-retained 10-unit implant-supported reconstruction on six implants (FDI positions 15, 13, 11, 21, 23, 25) were fabricated using a laser (ZrO-L, N = 6) and a mechanical scanner (ZrO-M, N = 5) for digitizing the implant platform and the cuspid-supporting framework resin pattern. Laser-scanned CAD/CAM titanium (TIT-L, N = 6) and cast CoCrW-alloy frameworks (Cast, N = 5) fabricated on the same model and designed similar to the ZrO frameworks were the control. The one-screw test (implant 25 screw-retained) was applied to assess the vertical microgap between implant and framework platform with a scanning electron microscope. The mean microgap was calculated from approximal and buccal values. Statistical comparison was performed with non-parametric tests.
  
  
  RESULTS
  No statistically significant pairwise difference was observed between the relative effects of vertical microgap between ZrO-L (median 14 μm; 95% CI 10-26 μm), ZrO-M (18 μm; 12-27 μm) and TIT-L (15 μm; 6-18 μm), whereas the values of Cast (236 μm; 181-301 μm) were significantly higher (P < 0.001) than the three CAD/CAM groups. A monotonous trend of increasing values from implant 23 to 15 was observed in all groups (ZrO-L, ZrO-M and Cast P < 0.001, TIT-L P = 0.044).
  
  
  CONCLUSIONS
  Optical and tactile scanners with CAD/CAM technology allow for the fabrication of highly accurate long-span screw-retained ZrO implant-reconstructions. Titanium frameworks showed the most consistent precision. Fit of the cast alloy frameworks was clinically inacceptable.
authors.affiliation: Department of Prosthodontics, School of Dental Medicine, University of Bern, Bern, Switzerland; Department of Preventive and Restorative Sciences, School of Dental Medicine, Robert Schattner Center, University of Pennsylvania, Philadelphia, PA, USA.
authors.forename: Joannis
authors.initials: J
authors.lastname: Katsoulis
authors.forename: Regina
authors.initials: R
authors.lastname: Mericske-Stern
authors.forename: Lolita
authors.initials: L
authors.lastname: Rotkina
authors.forename: Christoph
authors.initials: C
authors.lastname: Zbären
authors.forename: Norbert
authors.initials: N
authors.lastname: Enkling
authors.forename: Markus B
authors.initials: MB
authors.lastname: Blatz
mesh_terms: D001696:Biomechanical Phenomena; D001863:Bone Screws; D017076:Computer-Aided Design; D017267:Dental Prosthesis Design; D019094:Dental Prosthesis, Implant-Supported; D006801:Humans; D066298:In Vitro Techniques; D007834:Lasers; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D017755:Prosthesis Fitting / Q000295:instrumentation*; D014025:Titanium; D015040:Zirconium
chemical_list: D015040:Zirconium; D014025:Titanium; C028541:zirconium oxide