title: Shear bond strength of techniques for bonding esthetic veneers to metal.
abstract: BACKGROUND
  New composites with improved qualities have been introduced to the dental profession as alternatives to porcelain. There is concern about the strength and reliability of new metal-resin bonding systems when these composites are used as esthetic veneers over metal frameworks.
  
  
  OBJECTIVE
  This in vitro study compared the shear bond strength of 2 metal-resin bonding techniques with the bond strength of conventional porcelain fused-to-metal (PFM). Effects of water storage and thermocycling were also evaluated.
  
  
  METHODS
  Ninety disks, cast in a medium gold, high noble PFM alloy, were divided equally into 6 groups, and received 3 treatments for veneering: conventional feldspathic porcelain on 1 group, and a composite (Artglass) bonded to the metal, using 2 metal-resin bonding techniques. Specimens were tested in shear, half of them after a 24-hour dry storage at room temperature and the rest after 10-day storage in normal saline solution at 37 degrees C and thermocycling. Fractured specimens were evaluated under x10 magnification to determine the nature of failure. Statistical analysis was performed with 2-factor analysis of variance (ANOVA).
  
  
  RESULTS
  Mean shear bond strength values before and after wet storage and thermocycling were 29.66 and 22.91 MPa for the PFM group; 21.43 and 17.92 MPa for the Siloc group; and 19.34 and 15.64 for the etched group, respectively. The PFM group exhibited significantly higher bond strength values compared with the other 2 groups (P<.001). All groups showed a significant decrease in bond strength values after wet storage and thermocycling (P<.001).
  
  
  CONCLUSIONS
  Wet storage and thermocycling caused a significant decrease in shear bond strength of all specimens. Shear bond strength of conventional feldspathic PFM was significantly higher than that of the 2 metal-resin bonding techniques tested. The 2 latter techniques did not reveal any statistically significant differences.
authors.affiliation: Dental School, Aristotle University, Thessaloniki, Greece. lpetridis@the.forthnet.gr
authors.forename: H
authors.initials: H
authors.lastname: Petridis
authors.forename: H
authors.initials: H
authors.lastname: Hirayama
authors.forename: G
authors.initials: G
authors.lastname: Kugel
authors.forename: C
authors.initials: C
authors.lastname: Habib
authors.forename: P
authors.initials: P
authors.lastname: Garefis
mesh_terms: D000704:Analysis of Variance; D003188:Composite Resins / Q000737:chemistry; D003722:Dental Alloys / Q000737:chemistry*; D001840:Dental Bonding / Q000379:methods* / Q000706:statistics & numerical data; D003801:Dental Veneers / Q000706:statistics & numerical data; D004955:Esthetics, Dental; D006358:Hot Temperature; D006801:Humans; D008422:Materials Testing / Q000379:methods / Q000706:statistics & numerical data; D013718:Tensile Strength
chemical_list: D003188:Composite Resins; D003722:Dental Alloys