title: Shear bond strength of metal-ceramic repair systems.
abstract: BACKGROUND
  When clinical fractures of the ceramic veneer on metal-ceramic prostheses can be repaired, the need for remake may be eliminated or postponed. Many different ceramic repair materials are available, and bond strength data are necessary for predicting the success of a given repair system.
  
  
  OBJECTIVE
  This study evaluated the shear bond strength of different repair systems for metal-ceramic restorations applied on metal and porcelain.
  
  
  METHODS
  Fifty cylindrical specimens (9 x 3 mm) were fabricated in a nickel-chromium alloy (Vera Bond II) and 50 in feldspathic porcelain (Noritake). Metal (M) and porcelain (P) specimens were embedded in a polyvinyl chloride (PVC) ring and received 1 of the following bonding and resin composite repair systems (n=10): Clearfil SE Bond/Clearfil AP-X (CL), Bistite II DC/Palfique (BT), CoJet Sand/Z100 (CJ), Scotchbond Multipurpose Plus/Z100 (SB) (control group), or CoJet Sand plus Scotchbond Multipurpose Plus/Z100 (CJSB). The specimens were stored in distilled water for 24 hours at 37 degrees C, thermal cycled (1000 cycles at 5 degrees C to 55 degrees C), and stored at 37 degrees C for 8 days. Shear bond tests between the metal or ceramic specimens and repair systems were performed in a mechanical testing machine with a crosshead speed of 0.5 mm/min. Mean shear bond strength values (MPa) were submitted to 1-way ANOVA and Tukey honestly significant difference tests (alpha=.05). Each specimen was examined under a stereoscopic lens with x30 magnification, and mode of failure was classified as adhesive, cohesive, or a combination.
  
  
  RESULTS
  On metal, the mean shear bond strength values for the groups were as follows: MCL, 18.40 +/- 2.88(b); MBT, 8.57 +/- 1.00(d); MCJ, 25.24 +/- 3.46(a); MSB, 16.26 +/- 3.09(bc); and MCJSB, 13.11 +/- 1.24(c). On porcelain, the mean shear bond strength values of each group were as follows: PCL, 16.91 +/- 2.22(b); PBT, 18.04 +/- 3.23(ab); PCJ, 19.54 +/- 3.77(ab); PSB, 21.05 +/- 3.22(a); and PCJSB, 16.18 +/- 1.71(b). Within each substrate, identical superscript letters denote no significant differences among groups.
  
  
  CONCLUSIONS
  The bond strength for the metal substrate was significantly higher using the CJ system. For porcelain, SB, CJ, and BT systems showed the highest shear bond strength values, and only SB was significantly different compared to CL and CJSB (P<.05).
  
  
  CONCLUSIONS
  This study suggests that when fracture involves only feldspathic porcelain, any of the evaluated systems may be used, since the fracture occurred on the porcelain substrate and not on the bond interface of porcelain-restorative material. However, for the nickel-chromium alloy tested, the CoJet Sand system showed the best results for repair.
authors.affiliation: Araraquara Dental School, Sao Paulo State University (UNESP), Sao Paulo, Brazil. julianagsbr@yahoo.com.br
authors.forename: Juliana Gomes
authors.initials: JG
authors.lastname: dos Santos
authors.forename: Renata Garcia
authors.initials: RG
authors.lastname: Fonseca
authors.forename: Gelson Luis
authors.initials: GL
authors.lastname: Adabo
authors.forename: Carlos Alberto
authors.initials: CA
authors.lastname: dos Santos Cruz
mesh_terms: D000704:Analysis of Variance; D002858:Chromium Alloys; D001840:Dental Bonding / Q000379:methods*; D003776:Dental Porcelain; D017269:Dental Prosthesis Repair; D003799:Dental Stress Analysis; D003801:Dental Veneers; D019279:Resin Cements; D033081:Shear Strength; D018709:Statistics, Nonparametric
chemical_list: D002858:Chromium Alloys; D019279:Resin Cements; D003776:Dental Porcelain