title: Improving performance of dental resins by adding titanium dioxide nanoparticles.
abstract: OBJECTIVE
  The objective of this study is to improve the performance of dental resins by adding a small amount of titanium dioxide nanoparticles (TiO₂ NPs), which have outstanding mechanical properties and unique photoactivities.
  
  
  METHODS
  Acrylic acid modified TiO₂ NPs (AP25) were prepared and added to a mixture of bis-phenol-A-dimethacrylate and triethylene glycol dimethacrylate (mass ratio 1:1) at seven mass fractions. Disks made of these resins were subjected to FTIR microspectroscopy, nanoindentation, microindentation, and 3-point bending to determine the degree of vinyl conversion (DC) modulus and hardness. The shear bond strengths (SBS) of dentin adhesives containing various amount of AP25 were also examined.
  
  
  RESULTS
  The DC increased as a function of mass fraction of AP25 and reached a plateau at 0.1%. The DC of the resin mixture was improved by ≈7% up to 91.7 ± 0.8%. The elastic modulus and hardness of the composites increased initially as more AP25 were added, and decreased after reached the maximum value at approximately 0.06% mass fraction of AP25. The maximum elastic modulus was ≈48% higher than that of the NP-free resin, and the maximum hardness was more than twice higher than that of the NP-free resin. Using these resin composites as dental adhesives, the mean SBS using resins with 0.1% mass fraction of AP25 was ≈30% higher than those using NP-free resin.
  
  
  CONCLUSIONS
  By adding a small amount of AP25 to the resin, the DC and the mechanical properties of resins were improved dramatically. These findings could lead to better performing dental adhesives.
authors.affiliation: American Dental Association Foundation, Paffenbarger Research Center, Gaithersburg, MD 20899-8546, USA. jsun@nist.gov
authors.forename: Jirun
authors.initials: J
authors.lastname: Sun
authors.forename: Aaron M
authors.initials: AM
authors.lastname: Forster
authors.forename: Peter M
authors.initials: PM
authors.lastname: Johnson
authors.forename: Naomi
authors.initials: N
authors.lastname: Eidelman
authors.forename: George
authors.initials: G
authors.lastname: Quinn
authors.forename: Gary
authors.initials: G
authors.lastname: Schumacher
authors.forename: Xinran
authors.initials: X
authors.lastname: Zhang
authors.forename: Wen-Li
authors.initials: WL
authors.lastname: Wu
mesh_terms: D000179:Acrylates / Q000737:chemistry; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D003799:Dental Stress Analysis; D055119:Elastic Modulus; D006244:Hardness; D055115:Light-Curing of Dental Adhesives; D008422:Materials Testing; D053758:Nanoparticles; D018583:Pliability; D011092:Polyethylene Glycols / Q000737:chemistry; D011109:Polymethacrylic Acids / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry*; D033081:Shear Strength; D017550:Spectroscopy, Fourier Transform Infrared; D014025:Titanium
chemical_list: D000179:Acrylates; D011109:Polymethacrylic Acids; D019279:Resin Cements; C020946:triethylene glycol dimethacrylate; C009495:titanium dioxide; D011092:Polyethylene Glycols; D017438:Bisphenol A-Glycidyl Methacrylate; D014025:Titanium; C036658:acrylic acid