title: Passivity of fit of CAD/CAM and copy-milled frameworks, veneered frameworks, and anatomically contoured, zirconia ceramic, implant-supported fixed prostheses.
abstract: BACKGROUND
  There is less information on the quality of fit of zirconia frameworks with or without ceramic veneer than on anatomically contoured milled zirconia restorations.
  
  
  OBJECTIVE
  The purpose of this in vitro study was to evaluate the strain development of CAD/CAM fabricated zirconia ceramic frameworks with and without ceramic veneering, copy-milled zirconia ceramic frameworks, and copy-milled zirconia ceramic anatomic contour restorations.
  
  
  METHODS
  Four groups of 3-unit implant-supported cement-retained restorations were fabricated (n=10) to fit an in vitro model with 2 implants. Strain gauges which recorded the strain development of all restorations during cementation were attached to the model mesially and distally adjacent to the implants. Mean absolute strain values were recorded for statistical analysis (MANOVA with Pillai's trace; α=.05).
  
  
  RESULTS
  Mean absolute strain development at the different strain gauge locations ranged from 83.23 µm/m for copy-milled zirconia ceramic anatomic contour restorations to 301.20 µm/m for veneered CAD/CAM fabricated zirconia ceramic restorations. Significant effects (P<.001) of the fixed factors restoration type and veneering status, as well as of their interaction term (P=.001) were found. Ceramic veneering of CAD/CAM frameworks resulted in higher strain development, whereas the greater volume in copy-milled anatomic contour restorations did not affect accuracy.
  
  
  CONCLUSIONS
  With the systems used in this study, zirconia ceramic-based anatomic contour restorations show greater passivity of fit than ceramic veneered CAD/CAM fabricated zirconia ceramic frameworks.
authors.affiliation: Department of Prosthodontics, University of Erlangen-Nuremberg, Erlangen, Germany. Matthias.Karl@uk-erlangen.de
authors.forename: Matthias
authors.initials: M
authors.lastname: Karl
authors.forename: Friedrich
authors.initials: F
authors.lastname: Graef
authors.forename: Manfred
authors.initials: M
authors.lastname: Wichmann
authors.forename: Tim
authors.initials: T
authors.lastname: Krafft
mesh_terms: D002484:Cementation / Q000379:methods; D017076:Computer-Aided Design; D059605:Dental Implant-Abutment Design; D018772:Dental Marginal Adaptation; D003764:Dental Materials / Q000737:chemistry*; D003776:Dental Porcelain / Q000737:chemistry*; D019094:Dental Prosthesis, Implant-Supported; D003799:Dental Stress Analysis / Q000295:instrumentation; D003801:Dental Veneers; D003779:Denture Design; D003781:Denture Retention; D003830:Denture, Partial, Fixed; D005054:Eugenol / Q000737:chemistry; D006801:Humans; D008422:Materials Testing; D013314:Stress, Mechanical; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry; D015034:Zinc Oxide / Q000737:chemistry; D015035:Zinc Oxide-Eugenol Cement / Q000737:chemistry; D015040:Zirconium / Q000737:chemistry*
chemical_list: D003764:Dental Materials; D015035:Zinc Oxide-Eugenol Cement; D003776:Dental Porcelain; D005054:Eugenol; C076899:Temp-Bond; D015040:Zirconium; D014025:Titanium; C028541:zirconium oxide; D015034:Zinc Oxide