Fabrication and evaluation of light-curing nanocomposite resins filled with surface-modified TiO₂ nanoparticles for dental application

A kind of light-curing nanocomposite resin, which consisted of reactive monomers, surface-modified TiO₂ nanoparticles and a photoinitiation system, has been developed for the application of dental restoration. It may be noted that the conjugation of glycidyl methylmethacrylate (GMA) onto the surface of TiO₂ nanoparticles (nano-TiO₂) contributed to improvement in miscibility between nano-filler and matrix, because the reactive C=C group of GMA participated in curing of the matrix, and hence resulted in the enhancement of mechanical properties. When the content of GMA-modified nano-TiO₂ was 2 wt%, the flexural strength and modulus of the nanocomposite resin reached 147.8 and 2918.3 MPa, respectively, which increased by 21.7 and 30.8 % in contrast to the resin without adding nano-filler. Furthermore, the polymerization shrinkage decreased after incorporating the nano-filler while the degree of monomer conversion and the water sorption for the nanocomposite resins was comparable with those of the resin without nano-filler. In conclusion, this study presented a new method, namely introduction of functional groups onto the nano-filler surface to participate in the reaction of resin monomer, to improve the interfacial adhesion and the resultant miscibility between nano-filler and resin matrix in light-curing dental nanocomposites by chemical linkage mediated with surface-modified specie. Moreover, the enhanced mechanical properties and decreased polymerization shrinkage of nanocomposite resins, which are considered the key to the effects of dental restoration, contributed a great potential as a dental material utilized for caries treatment and prevention.