title: Knoop hardness and effectiveness of dual-cured luting systems and flowable resin to bond leucite-reinforced ceramic to enamel.
abstract: OBJECTIVE
  The aim of this study was to evaluate the Knoop microhardness and microshear bond strength (MSBS) of dual-cured luting systems and flowable resin bonded to leucite-reinforced ceramics and enamel.
  
  
  METHODS
  Eighty bovine incisors were randomly divided into four groups per test (microhardness and microshear; n = 10) according to the bonding procedure: Excite DSC/Variolink, Clearfil SE Bond/Panavia F, Adper Scotchbond Multi-Purpose Plus/RelyX ARC, and Adper Single Bond 2/Filtek Z350 Flow. For the KHN measurement, the cement was applied on the enamel surface and light-cured through a ceramic disk (5 mm diameter × 1.2 mm thick). Five indentations were performed in each specimen and measured at HMV-2. For the microshear test, two cylinders of a leucite-reinforced ceramic (1 mm diameter × 2 mm height) were bonded to the enamel substrate in accordance with the bonding procedures previously established. One cylinder was tested 24 hours after cementation, and the other was subjected to thermocycling (2000 cycles) and then submitted to an MSBS test. The data from the hardness and bond strength tests were subjected to one- and two-way repeated-measures analysis of variance (ANOVA), respectively, and to Tukey's test (α= 0.05).
  
  
  RESULTS
  Scotchbond/RelyX ARC presented higher values of bond strength, while Single Bond/Z350 Flow showed lower values. The thermocycling promoted a reduction in the bond strength values for all groups. Panavia F presented higher values of KHN, and the flowable resin presented the lowest. RelyX ARC and Variolink presented intermediate values on hardness evaluation.
  
  
  CONCLUSIONS
  For ceramic cementation, dual-cured resin luting systems promoted more reliable bonding and microhardness values than the flowable resin.
authors.affiliation: Department of Restorative Dentistry, Piracicaba Dental School - State University of Campinas, Piracicaba, Brazil.
authors.forename: Lúcia Trazzi
authors.initials: LT
authors.lastname: Prieto
authors.forename: Eduardo José
authors.initials: EJ
authors.lastname: Souza
authors.forename: Cíntia Tereza Pimenta
authors.initials: CT
authors.lastname: Araújo
authors.forename: Adriano Fonseca
authors.initials: AF
authors.lastname: Lima
authors.forename: Carlos Tadeu dos Santos
authors.initials: CT
authors.lastname: Dias
authors.forename: Luis Alexandre Maffei Sartini
authors.initials: LA
authors.lastname: Paulillo
mesh_terms: D000538:Aluminum Silicates; D000818:Animals; D002417:Cattle; D002484:Cementation / Q000379:methods; D001840:Dental Bonding / Q000379:methods*; D003743:Dental Enamel; D003776:Dental Porcelain / Q000737:chemistry; D003799:Dental Stress Analysis; D006244:Hardness; D008422:Materials Testing; D011897:Random Allocation; D019279:Resin Cements / Q000737:chemistry; D012212:Rheology; D055116:Self-Curing of Dental Resins; D033081:Shear Strength
chemical_list: D000538:Aluminum Silicates; D019279:Resin Cements; D003776:Dental Porcelain; C078519:leucite