title: Retentive strengths of cast gold crowns using glass ionomer, compomer, or resin cement.
abstract: OBJECTIVE
  The retention forces of a newly developed compomer cement (Dyract Cem), a glass ionomer cement (Ketac Cem Aplicap), and a resin cement (F21) were examined.
  
  
  METHODS
  Cemented cast gold crowns were removed along the path of insertion with a Zwick universal testing device. The impact of both a cured and a noncured additional bonding layer that were applied to the inner surface of the crowns was examined across the Dyract Cem group.
  
  
  RESULTS
  The mean adhesive strength was measured at 2.36 +/- 0.69 N/mm2 in the Ketac Cem group, at 0.60 +/- 0.28 N/mm2 in the F21 group, and at 1.85 +/- 0.94 N/mm2 in the Dyract Cem group, respectively. The application of an additional bonding layer to the inner surface of the crowns did not significantly improve the retentive strength of Dyract Cem; the respective mean strengths were observed at 1.46 +/-0.33 N/mm2 for the uncured and at 1.70 +/- 0.76 N/mm2 for the cured bonding layers.
  
  
  CONCLUSIONS
  Dyract Cem and Ketac Cem showed significantly higher retentive strengths than F21 (p < 0.001, Wilcoxon test, 5% level). No significant difference was found in bond strength between Ketac Cem and Dyract Cem.
authors.affiliation: Department of Restorative Dentistry, Johannes Gutenberg-University, Mainz, Germany.
authors.forename: C P
authors.initials: CP
authors.lastname: Ernst
authors.forename: N
authors.initials: N
authors.lastname: Wenzl
authors.forename: E
authors.initials: E
authors.lastname: Stender
authors.forename: B
authors.initials: B
authors.lastname: Willershausen
mesh_terms: D000268:Adhesiveness; D002484:Cementation; D020770:Compomers; D003188:Composite Resins / Q000737:chemistry; D003442:Crowns; D001840:Dental Bonding / Q000379:methods; D003738:Dental Cements / Q000737:chemistry; D017268:Dental Prosthesis Retention; D003799:Dental Stress Analysis / Q000295:instrumentation; D003804:Dentin / Q000648:ultrastructure; D005899:Glass Ionomer Cements / Q000737:chemistry; D006047:Gold Alloys / Q000737:chemistry; D006801:Humans; D008277:Magnesium Oxide / Q000737:chemistry; D008689:Methacrylates / Q000737:chemistry; D011076:Polycarboxylate Cement / Q000737:chemistry; D011091:Polyesters / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry; D017640:Silicates / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D015034:Zinc Oxide / Q000737:chemistry
chemical_list: D020770:Compomers; D003188:Composite Resins; D003738:Dental Cements; C088486:Dyract; C087762:F21; D005899:Glass Ionomer Cements; D006047:Gold Alloys; D008689:Methacrylates; D011076:Polycarboxylate Cement; D011091:Polyesters; D019279:Resin Cements; D017640:Silicates; D008277:Magnesium Oxide; C040235:Ketac-cem; D015034:Zinc Oxide