title: Effect of intermediate adhesive resin and flowable resin application on the interfacial adhesion of resin composite to pre-impregnated unidirectional S2-glass fiber bundles.
abstract: OBJECTIVE
  This study evaluated the effect of either an intermediate application of adhesive resin or flowable resin application on the adhesion of particulate filler composite (PFC) to glass fiber-reinforced composite (FRC).
  
  
  METHODS
  Unidirectional, pre-impregnated S2-glass fiber bundles (Dentapreg) (length: 40 mm; thickness: 0.5 mm) were obtained (N = 30, n = 10 per group) and secured in translucent silicone material with the adhesion surface exposed and photopolymerized. They were randomly divided into 3 groups for the following adhesion sequence: A) FRC+PFC, B) FRC+intermediate adhesive resin+PFC, C) FRC+flowable resin+PFC. The PFC was applied in a polyethylene mold onto the FRC and photopolymerized. PFCs were debonded from the FRC surface using shear bond test in a universal testing machine (1 mm/min). After debonding, all specimens were analyzed using scanning electron microscopy to categorize the failure modes. The data were statistically analyzed using one-way ANOVA and Tukey's tests (α = 0.05).
  
  
  RESULTS
  A significant difference was observed between the groups (p < 0.05). The highest mean bond strength value was obtained with the application of an intermediate layer of adhesive resin (group B: 19.4 ± 1.1 MPa) (p < 0.05) followed by group A (14.1 ± 0.6 MPa) and group C (10.4 ± 0.8 MPa), which were also significantly different from one another (p < 0.05). Group A exclusively presented a combination of partial cohesive failure in the PFC and adhesive failure between the FRC and PFC. While group B showed large cohesive defects in the FRC, in group C, only small cohesive failures were observed in the FRC.
  
  
  CONCLUSIONS
  Based on the highest mean bond strength and the large cohesive failures within the FRC, application of an intermediate layer of adhesive resin on the S2-glass FRC surface prior to incremental build up of the PFC seems to be compulsory.
authors.forename: Petr
authors.initials: P
authors.lastname: Polacek
authors.forename: Vladimir
authors.initials: V
authors.lastname: Pavelka
authors.forename: Mutlu
authors.initials: M
authors.lastname: Özcan
mesh_terms: D000268:Adhesiveness; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry*; D001840:Dental Bonding; D003738:Dental Cements / Q000737:chemistry; D003764:Dental Materials / Q000737:chemistry*; D003799:Dental Stress Analysis / Q000295:instrumentation; D005898:Glass / Q000737:chemistry*; D006801:Humans; D055115:Light-Curing of Dental Adhesives; D008689:Methacrylates / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D058105:Polymerization; D033081:Shear Strength; D012822:Silicon Dioxide / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties
chemical_list: C554641:Adper single bond 2; D003188:Composite Resins; D003738:Dental Cements; D003764:Dental Materials; D008689:Methacrylates; C009753:fiberglass; D017438:Bisphenol A-Glycidyl Methacrylate; C005044:hydroxyethyl methacrylate; D012822:Silicon Dioxide