title: Effect of Jig Design and Assessment of Stress Distribution in Testing Metal-Ceramic Adhesion.
abstract: OBJECTIVE
  In testing adhesion using shear bond test, a combination of shear and tensile forces occur at the interface, resulting in complex stresses. The jig designs used for this kind of test show variations in published studies, complicating direct comparison between studies. This study evaluated the effect of different jig designs on metal-ceramic bond strength and assessed the stress distribution at the interface using finite element analysis (FEA).
  
  
  METHODS
  Metal-ceramic (Metal: Ni-Cr, Wiron 99, Bego; Ceramic: Vita Omega 900, Vita) specimens (N = 36) (diameter: 4 mm, veneer thickness: 4 mm; base diameter: 5 mm, thickness: 1 mm) were fabricated and randomly divided into three groups (n = 12 per group) to be tested using one of the following jig designs: (a) chisel (CH) (ISO 11405), (b) steel strip (SS), (c) piston (PI). Metal-ceramic interfaces were loaded under shear until debonding in a universal testing machine (0.5 mm/min). Failure types were evaluated using scanning electron microscopy (SEM). FEA was used to study the stress distribution using different jigs. Metal-ceramic bond strength data (MPa) were analyzed using ANOVA and Tukey's tests (α = 0.05).
  
  
  RESULTS
  The jig type significantly affected the bond results (p = 0.0001). PI type of jig presented the highest results (MPa) (p < 0.05) (58.2 ± 14.8), followed by CH (38.7 ± 7.6) and SS jig type (23.3 ± 4.2) (p < 0.05). Failure types were exclusively a combination of cohesive failure in the opaque ceramic and adhesive interface failure. FEA analysis indicated that the SS jig presented slightly more stress formation than with the CH jig. The PI jig presented small stress concentration with more homogeneous force distribution compared to the CH jig where the stress concentrated in the area where the force was applied.
  
  
  CONCLUSIONS
  Metal-ceramic bond strength was affected by the jig design. Accordingly, the results of in vitro studies on metal-ceramic adhesion should be evaluated with caution.
  
  
  CONCLUSIONS
  When adhesion of ceramic materials to metals is evaluated in in vitro studies, it should be noted that the loading jig type affects the results. Clinical observations should report on the location and type of ceramic fractures in metal-ceramic reconstructions so that the most relevant test method can be identified.
authors.affiliation: University of Zurich, Dental Materials Unit, Center for Dental and Oral Medicine, Clinic for Fixed and Removable Prosthodontics and Dental Materials Science, Zurich, Switzerland.
authors.forename: Mutlu
authors.initials: M
authors.lastname: Özcan
authors.affiliation: Department of Dental Materials and Prosthodontics, São Paulo State University at São Jose dos Campos, São Paulo, Brazil.
authors.forename: Alberto Noriyuki
authors.initials: AN
authors.lastname: Kojima
authors.affiliation: Department of Prosthodontics, Paulista University at São Paulo, São Paulo, Brazil.
authors.forename: Renato Sussumu
authors.initials: RS
authors.lastname: Nishioka
authors.affiliation: Department of Prosthodontics, Paulista University at São Paulo, São Paulo, Brazil.
authors.forename: Alfredo Mikail Melo
authors.initials: AM
authors.lastname: Mesquita
authors.affiliation: Department of Dental Materials and Prosthodontics, São Paulo State University at São Jose dos Campos, São Paulo, Brazil.
authors.forename: Marco Antonio
authors.initials: MA
authors.lastname: Bottino
authors.affiliation: Department of Dental Materials and Prosthodontics, São Paulo State University at São Jose dos Campos, São Paulo, Brazil.
authors.forename: Gilberto Duarte
authors.initials: GD
authors.lastname: Filho
mesh_terms: D002516:Ceramics; D001840:Dental Bonding; D003776:Dental Porcelain; D003799:Dental Stress Analysis; D006801:Humans; D008422:Materials Testing; D008670:Metals; D033081:Shear Strength; D013314:Stress, Mechanical; D013499:Surface Properties
chemical_list: D008670:Metals; D003776:Dental Porcelain
keywords: adhesion; bond testing; dental porcelain; finite element analysis; shear bond test