title: Effect of post-silanization heat treatments of silanized feldspathic ceramic on adhesion to resin cement.
abstract: OBJECTIVE
  To evaluate the effect of post-silanization heat treatment of a silane agent and rinsing with hot water of silanized CAD/CAM feldspathic ceramic surfaces on the microtensile bond strength between resin cement and the ceramic, before and after mechanical cycling.
  
  
  METHODS
  Blocks measuring 10 x 5.7 x 3.25 mm3 were produced from feldspathic ceramic cubes (VITA Mark II, VITA Zanhfabrik). Each ceramic block was duplicated in composite resin using a template made of polyvinylsiloxane impression material. Afterwards, ceramic and corresponding resin composite blocks were ultrasonically cleaned and randomly divided according to the 5 strategies used for conditioning the ceramic surface (n = 10): GHF: etching with hydrofluoric acid 10% + rinsing with water at room temperature + silanization at 20°C; G20: silanization; G77: silanization + oven drying at 77°C; G20r: silanization + hot water rinsing; G77r: silanization + oven drying at 77°C + hot water rinsing. The resin and ceramic blocks were cemented using a dualcuring resin cement. Every group was divided in two subgroups: aging condition (mechanical cycling, designated as a) or non-aging (designated as n). All the bonded assemblies were sectioned into microsticks for microtensile bond strength (µTBS) testing. The failure mode of the tested specimens was assessed and µTBS data were statistically analyzed in two ways: first 2-way ANOVA (GHF, G20 and G77 in non-aging/aging conditions) and 3-way ANOVA (temperature x rinsing x aging factors, excluding GHF), followed by Tukey's test (p = 0.05).
  
  
  RESULTS
  The 2-way ANOVA revealed that the µTBS was significantly affected by the surface treatment (p < 0.001) but not by aging (p = 0.68), and Tukey's test showed that G77-n/G77-a (18.0 MPa) > GHF-n/GHF-a (12.2 MPa) > G20-n/G20-a (9.1 MPa). The 3-way ANOVA revealed that the µTBS was significantly affected by the "heat treatment" and "rinsing" factors (p < 0.001), but not affected by "aging" (p = 0.36). The rinsing procedure decreased, while oven drying increased the bond strengths. Group G77, in both non-aging and aging conditions (18.6-17.4 MPa), had the highest bond values. Failure modes were mainly mixed for all groups.
  
  
  CONCLUSIONS
  Oven drying at 77°C improved the bond strength between the resin cement and feldspathic ceramic, but hot water rinsing reduced the bond strength and should not be recommended.
authors.forename: Pedro Henrique
authors.initials: PH
authors.lastname: Corazza
authors.forename: Samia Carolina
authors.initials: SC
authors.lastname: Cavalcanti
authors.forename: José Renato
authors.initials: JR
authors.lastname: Queiroz
authors.forename: Marco Antonio
authors.initials: MA
authors.lastname: Bottino
authors.forename: Luiz Felipe
authors.initials: LF
authors.lastname: Valandro
mesh_terms: D000134:Acid Etching, Dental / Q000379:methods; D000268:Adhesiveness; D000538:Aluminum Silicates / Q000737:chemistry*; D002484:Cementation / Q000379:methods; D003188:Composite Resins / Q000737:chemistry; D017076:Computer-Aided Design; D001840:Dental Bonding; D003776:Dental Porcelain / Q000737:chemistry*; D006358:Hot Temperature; D006801:Humans; D006858:Hydrofluoric Acid / Q000737:chemistry; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D017680:Potassium Compounds / Q000737:chemistry*; D019279:Resin Cements / Q000737:chemistry*; D055116:Self-Curing of Dental Resins; D012821:Silanes / Q000737:chemistry*; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D013718:Tensile Strength; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D000538:Aluminum Silicates; D003188:Composite Resins; D017680:Potassium Compounds; D019279:Resin Cements; D012821:Silanes; C082340:Vita Mark II; D014867:Water; D003776:Dental Porcelain; C016447:feldspar; C103502:Variolink; D006858:Hydrofluoric Acid