title: Marginal discrepancy of monolithic and veneered all-ceramic crowns on titanium and zirconia implant abutments before and after adhesive cementation: a scanning electron microscopy analysis.
abstract: OBJECTIVE
  To evaluate the marginal discrepancy of monolithic and veneered all-ceramic crown systems cemented on titanium (Ti) and zirconia implant abutments.
  
  
  METHODS
  Sixty customized implant abutments for a maxillary right central incisor were fabricated of Ti and zirconia (n = 30 of each) for an internal-connection implant system. All-ceramic crowns were fabricated using the following systems (n = 10 per group): monolithic with computer-aided design/computer-assisted manufacture (CAD/CAM) lithium disilicate (MLD), pressed lithium disilicate (PLD), or CAD yttrium-stabilized tetragonal zirconia polycrystal (Y-TZP). The frameworks of the PLD and Y-TZP systems were manually veneered with a fluorapatite-based ceramic. The crowns were cemented to their implant abutments, and the absolute marginal discrepancy of the gap was measured before and after cementation. Data were analyzed statistically.
  
  
  RESULTS
  Marginal discrepancies were significantly influenced by the crown system and by cementation, but the material did not significantly affect the results. Interaction terms were not significant. Y-TZP crowns on both Ti and zirconia abutments presented the smallest mean marginal discrepancies before (52.1 ± 17 μm and 56.2 ± 11 μm, respectively) and after cementation (98.7 ± 17 μm and 101.8 ± 16 μm, respectively). Before cementation, MLD crowns showed significantly larger mean marginal openings than PLD crowns on both Ti and zirconia abutments (75.2 ± 12 and 77.5 ± 13 μm for MLD, 52.1 ± 17 μm and 69.7 ± 8 μm for PLD, respectively). After cementation, both Ti and zirconia abutments with MLD crowns (113.5 ± 12 μm and 118.3 ± 14 μm, respectively) showed significantly larger values than with PLD crowns (98.7 ± 17 μm and 109.4 ± 9 μm, respectively).
  
  
  CONCLUSIONS
  Manually veneered Y-TZP crowns demonstrated more favorable marginal fit on both Ti and zirconia implant abutments before and after cementation compared to those of MLD and PLD.
authors.affiliation: University of Zurich, Dental Materials Unit, Center for Center for Dental and Oral Medicine, Clinic for Fixed and Removable Prosthodontics and Dental Materials Science, Plattenstrasse, Zurich, Switzerland.
authors.forename: Francisco
authors.initials: F
authors.lastname: Martinez-Rus
authors.forename: Alberto
authors.initials: A
authors.lastname: Ferreiroa
authors.forename: Mutlu
authors.initials: M
authors.lastname: Ozcan
authors.forename: Guillermo
authors.initials: G
authors.lastname: Pradies
mesh_terms: D002484:Cementation / Q000379:methods*; D002516:Ceramics; D017076:Computer-Aided Design; D003442:Crowns; D003738:Dental Cements; D059605:Dental Implant-Abutment Design; D003776:Dental Porcelain; D017267:Dental Prosthesis Design; D017268:Dental Prosthesis Retention / Q000379:methods; D003801:Dental Veneers; D007180:Incisor; D008437:Maxilla; D008855:Microscopy, Electron, Scanning; D014025:Titanium; D015019:Yttrium; D015040:Zirconium
chemical_list: D003738:Dental Cements; C493120:lithia disilicate; D003776:Dental Porcelain; D015019:Yttrium; D015040:Zirconium; D014025:Titanium; C028541:zirconium oxide