title: Nanofiller loading level: Influence on selected properties of an adhesive resin.
abstract: OBJECTIVE
  To evaluate the effect of the filler content in the cohesive strength (sigma), Weibull modulus (m) and degree of conversion (DC) of an experimental adhesive system.
  
  
  METHODS
  A HEMA/Bis-GMA/TEGDMA-based adhesive was formulated and filled with silica nanofillers in the following weight percentages (wt%): R0=0%; R1=1%; R3=3%; R5=5% and R10=10%. The adhesive of Adper Scotchbond Multi-Purpose (SBMP) system was used as a commercial reference. Twenty dumbbell-shaped specimens with cross-sectional area of 0.5mm(2) were made per group and tensile tested with a crosshead speed of 0.5mm/min until fracture. The cohesive strength was calculated in MPa. DC was obtained through FTIR after light curing for 25s. Data were submitted to one-way ANOVA and Tukey's test (alpha=0.05) and to Weibull analysis.
  
  
  RESULTS
  Mean sigma results were: R0=65.4+/-8.4; R1=73.2+/-8.8; R3=72.0+/-8.4; R5=73.1+/-9.7; R10=85.5+/-13.1 and SBMP=79.0+/-11.0MPa. R10 presented the highest sigma, while R0 showed the lowest. R5 and SBMP did not differ significantly (p<0.05). Weibull analysis revealed no significant difference in structural reliability between groups. The experimental adhesives presented similar results of DC, which, in turn, were significantly higher than the SBMP.
  
  
  CONCLUSIONS
  The addition of 10% filler in weight improves the cohesive strength of the adhesive, not interfering in the structural reliability or the degree of conversion.
authors.affiliation: Biomaterials Development and Control Center, Federal University of Pelotas, RS, Brazil.
authors.forename: M C M
authors.initials: MC
authors.lastname: Conde
authors.forename: C H
authors.initials: CH
authors.lastname: Zanchi
authors.forename: S A
authors.initials: SA
authors.lastname: Rodrigues-Junior
authors.forename: N L V
authors.initials: NL
authors.lastname: Carreño
authors.forename: F A
authors.initials: FA
authors.lastname: Ogliari
authors.forename: E
authors.initials: E
authors.lastname: Piva
mesh_terms: D000268:Adhesiveness; D017438:Bisphenol A-Glycidyl Methacrylate; D003799:Dental Stress Analysis; D006244:Hardness; D055115:Light-Curing of Dental Adhesives; D008422:Materials Testing; D008689:Methacrylates; D053761:Nanocomposites; D010316:Particle Size; D044367:Phase Transition; D011092:Polyethylene Glycols; D011109:Polymethacrylic Acids; D019279:Resin Cements / Q000737:chemistry; D012822:Silicon Dioxide; D017550:Spectroscopy, Fourier Transform Infrared; D016019:Survival Analysis
chemical_list: D008689:Methacrylates; D011109:Polymethacrylic Acids; D019279:Resin Cements; C020946:triethylene glycol dimethacrylate; D011092:Polyethylene Glycols; D017438:Bisphenol A-Glycidyl Methacrylate; C005044:hydroxyethyl methacrylate; D012822:Silicon Dioxide