title: Effect of thermocycling with or without 1 year of water storage on retentive strengths of luting cements for zirconia crowns.
abstract: BACKGROUND
  Bond stability between zirconia crowns and luting cement and between cement and dentin is a main concern; however, only limited evidence is available as to its longevity.
  
  
  OBJECTIVE
  The purpose of this in vitro study was to measure the retentive strengths of 7 self-adhesive cements (RelyX Unicem Aplicap, RelyX Unicem Clicker, RelyX Unicem 2 Automix, iCEM, Maxcem Elite, Bifix SE, SpeedCem), 2 adhesive cements with self-etch primers (Panavia 21, SEcure), 1 glass ionomer cement (Ketac Cem), 1 resin-modified glass ionomer cement (Meron Plus), and 1 zinc phosphate cement for luting zirconia crowns (LAVA) to extracted teeth after thermocycling with or without 1 year of water storage.
  
  
  METHODS
  Two-hundred-forty extracted human molars (2 treatments; n=10 per cement) were prepared in a standardized manner. All cements were used according to the manufacturers' recommendations. The intaglios of the crowns were treated with airborne-particle abrasion. After thermocycling (×5000, 5°C/55°C) with or without 1 year of water storage, the cemented ceramic crowns were removed by using a Zwick universal testing device. Statistical analyses were done with the Wilcoxon rank sum and the 2-independent-samples Kolmogorov-Smirnov test.
  
  
  RESULTS
  Median retentive strengths [MPa] for specimens thermocycled only/thermocycled with 1 year of water storage were as follows: Panavia 21: 1.7/2.5, SEcure: 3.0/3.0, RelyX Unicem Aplicap: 3.1/3.4, RelyX Unicem Clicker: 4.1/4.2, RelyX Unicem 2 Automix: 3.8/3.1, iCEM: 2.3/2.7, Maxcem Elite: 3.0/3.2, Bifix SE: 1.7/1.7, SpeedCem: 1.3/1.6, Meron Plus: 3.1/2.7, Ketac Cem: 1.4/1.4, and zinc phosphate cement: 1.1/1.6. Statistically significant differences were found only among specimens thermocycled only or thermocycled with 1-year water storage (P<.001).
  
  
  CONCLUSIONS
  Significant differences in retentive strengths were observed among cements after thermocycling only or thermocycling with 1 year of water storage, but not for the effect of the additional 1 year of water storage.
authors: Assistant Professor, Department of Operative Dentistry, University Medical Center of the Johannes Gutenberg University of Mainz, Mainz, Germany. Electronic address: ehlersv@uni-mainz.de.
authors: Vicky
authors: V
authors: Ehlers
authors: Doctoral student, Department of Operative Dentistry, University Medical Center of the Johannes Gutenberg University of Mainz, Mainz, Germany.
authors: Gabriel
authors: G
authors: Kampf
authors: Assistant Professor, Institute for Materials Science and Technology, University Medical Center of the Johannes Gutenberg University of Mainz, Mainz, Germany.
authors: Elmar
authors: E
authors: Stender
authors: Professor and Chair, Department of Operative Dentistry, University Medical Center of the Johannes Gutenberg University of Mainz, Mainz, Germany.
authors: Brita
authors: B
authors: Willershausen
authors: Professor, Department of Operative Dentistry, University Medical Center of the Johannes Gutenberg University of Mainz, Mainz, Germany.
authors: Claus-Peter
authors: CP
authors: Ernst
mesh_terms: D002484:Cementation / Q000379:methods; D003188:Composite Resins / Q000737:chemistry; D003442:Crowns; D001840:Dental Bonding; D003738:Dental Cements / Q000737:chemistry*; D003764:Dental Materials / Q000737:chemistry*; D003775:Dental Polishing / Q000379:methods; D017268:Dental Prosthesis Retention; D005899:Glass Ionomer Cements / Q000737:chemistry; D006801:Humans; D008277:Magnesium Oxide / Q000737:chemistry; D008422:Materials Testing; D010710:Phosphates / Q000737:chemistry; D011076:Polycarboxylate Cement / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry; D013696:Temperature; D013997:Time Factors; D014867:Water / Q000737:chemistry; D015034:Zinc Oxide / Q000737:chemistry; D015036:Zinc Phosphate Cement / Q000737:chemistry; D015040:Zirconium / Q000737:chemistry*
chemical_list: C515607:Bifix composite; D003188:Composite Resins; D003738:Dental Cements; D003764:Dental Materials; D005899:Glass Ionomer Cements; C515955:Maxcem; C488845:Meron; C093719:Panavia TPN-S; D010710:Phosphates; D011076:Polycarboxylate Cement; C483701:Rely X Unicem; D019279:Resin Cements; C081645:Secure resin cement; D014867:Water; D008277:Magnesium Oxide; D015036:Zinc Phosphate Cement; C040235:Ketac-cem; D015040:Zirconium; C028541:zirconium oxide; D015034:Zinc Oxide