title: Dislodgement Resistance of Zirconia Copings Cemented onto Zirconia and Titanium Abutments.
abstract: OBJECTIVE
  To determine the effect of the cement type and abutment material on the tensile strength required to dislodge zirconia copings.
  
  
  METHODS
  Two experimental groups of abutments were prepared: (1) titanium abutments (n = 30) and (2) zirconia abutments (n = 30). Sixty zirconia copings (custom designed) were fabricated using 3-dimensional computer-assisted design to have a 6-mm projection above the abutment to accommodate a hole, through which a wire was inserted to attach the zirconia coping to a universal testing machine. Each abutment was placed onto an implant analog embedded in acrylic resin blocks to fit onto the universal testing machine. The zirconia copings were cemented onto the abutments with a provisional luting agent, zinc phosphate (ZP) cement, and adhesive resin cement, and after 5500 thermocycles, a tensile force was applied at a crosshead speed of 0.5 mm/min. The removal force was recorded for each specimen. Two-way analysis of variance (ANOVA) and 1-way ANOVA were used for the statistical analysis (P < 0.05).
  
  
  RESULTS
  The mean forces necessary to remove the zirconia copings from titanium abutments were 6.52, 83.09, and 251.18 N for temporary cement, ZP cement, and resin cement, respectively. For zirconia abutments, the required forces were 17.82, 116.41, and 248.72 N.
  
  
  CONCLUSIONS
  The abutment material had no effect on retention, but the cement type affected the retention of the zirconia copings.
authors.affiliation: *Department of Prosthodontics, Faculty of Dentistry, Hacettepe University, Sihhiye Ankara, Turkey (deceased). †Dentram Dental Clinics, Istanbul, Turkey. ‡Department of Biotechnology, UnP-Laureate University, Natal, Brazil. §Department of Prosthodontics, Faculty of Dentistry, State University of Paraiba, Campina Grande, Brazil. ¶Dental Materials Unit, Clinic for Fixed and Removable Prosthodontics and Dental Materials Science, Center for Dental and Oral Medicine, University of Zürich, Zürich, Switzerland.
authors.forename: Umut
authors.initials: U
authors.lastname: Güler
authors.forename: Yasemin
authors.initials: Y
authors.lastname: Budak
authors.forename: José Renato Cavalcanti
authors.initials: JRC
authors.lastname: Queiroz
authors.forename: Mutlu
authors.initials: M
authors.lastname: Özcan
mesh_terms: D017076:Computer-Aided Design; D000044:Dental Abutments; D003764:Dental Materials / Q000737:chemistry*; D017267:Dental Prosthesis Design; D017268:Dental Prosthesis Retention; D003799:Dental Stress Analysis; D008422:Materials Testing; D019279:Resin Cements / Q000737:chemistry*; D013718:Tensile Strength; D014025:Titanium / Q000737:chemistry*; D015036:Zinc Phosphate Cement / Q000737:chemistry*; D015040:Zirconium / Q000737:chemistry*
chemical_list: D003764:Dental Materials; D019279:Resin Cements; D015036:Zinc Phosphate Cement; D015040:Zirconium; D014025:Titanium; C028541:zirconium oxide