title: Comparison of two test designs for evaluating the shear bond strength of resin composite cements.
abstract: OBJECTIVE
  To compare a shear bond strength test for resin composite cements developed in order to better consider the shrinkage stress (here termed "Swiss shear test") with the shear test design according to ISO 29022.
  
  
  METHODS
  Four restorative materials (VITA Enamic (VE), VITA Suprinity (VS), Vitablocs Mark II (VM) and VITA YZ T (YZ)) served as substrate. VE, VS and VM were polished or etched. YZ was polished, sandblasted or etched. Specimens were either bonded according to the Swiss or the ISO shear test. RelyX Unicem 2 Automix, Maxcem Elite and PermaFlo DC were used as cements. Shear bond strength (SBS) was measured. Failure modes (adhesive, cohesive or mixed) were evaluated by means of SEM.
  
  
  RESULTS
  Mean SBS values obtained with the Swiss shear test were significantly lower than those obtained with the ISO shear test. VE and VM exhibited similar SBS, values of VS were significantly higher. On etched surfaces VM and VE exhibited primarily cohesive failures, VS primarily adhesive failures. On polished substrates significantly lower bond strength values and exclusively adhesive failures were observed. YZ exhibited solely adhesive failures. Compared to polished YZ, SBS significantly increased after sandblasting and even more after etching. Only for adhesively failed specimens mean SBS values of Swiss and ISO shear test were strongly correlated.
  
  
  CONCLUSIONS
  Both test designs showed the same ranking of test results. When adhesive failure occurred test results were strongly correlated. When cohesive failure was involved, both test designs did not provide reliable results.
authors.affiliation: Department of Materials Science and Engineering, University Hospital for Dental Medicine, University of Basel, Basel, Switzerland.
authors.forename: M
authors.initials: M
authors.lastname: Hu
authors.affiliation: Clinic for Periodontology, Endodontology and Cariology, University Hospital of Dental Medicine, University of Basel, Basel, Switzerland.
authors.forename: R
authors.initials: R
authors.lastname: Weiger
authors.affiliation: Department of Materials Science and Engineering, University Hospital for Dental Medicine, University of Basel, Basel, Switzerland; VITA Zahnfabrik, Bad Säckingen, Germany. Electronic address: jens.fischer@unibas.ch.
authors.forename: J
authors.initials: J
authors.lastname: Fischer
mesh_terms: D002516:Ceramics / Q000737:chemistry*; D003188:Composite Resins / Q000737:chemistry*; D003764:Dental Materials / Q000737:chemistry*; D003776:Dental Porcelain / Q000737:chemistry*; D008422:Materials Testing / Q000379:methods*; D008855:Microscopy, Electron, Scanning; D019279:Resin Cements / Q000737:chemistry; D033081:Shear Strength; D013499:Surface Properties
chemical_list: D003188:Composite Resins; D003764:Dental Materials; C515955:Maxcem; C423507:PermaFlow; C483701:Rely X Unicem; D019279:Resin Cements; C000621297:VITA Enamic; C000621298:VITA Suprinity; C000621299:VITA YZ T; C096477:Vitabloc MK1; D003776:Dental Porcelain
keywords: Adhesion; Ceramic; Resin composite cement; Shear bond strength; Test methods