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 11) 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. SIGNIFICANCE: 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.