Radiopaque dental adhesives: Dispersion of flame-made Ta₂O₅/SiO₂ nanoparticles in methacrylic matrices

Abstract 

Objectives

Radiopaque dental adhesive (DA) of low viscosity were made by forming stable suspensions of weakly agglomerated Ta₂O₅/SiO₂ nanoparticles with primary particle size of about 10nm.

Methods

The particles were prepared by one-step flame-spray pyrolysis. Particles were functionalized with γ-methacryloxypropyltrimethoxysilane (MPS) and dispersed in a methacrylic monomer matrix by centrifugal mixing and ultrasonication. Particle size distributions were analyzed by X-ray disc centrifugation of suspensions and TEM analysis of cured sample composites, while average primary particle size was obtained by N₂ adsorption and X-ray diffraction.

Results

The dispersion method affected the aggregate size distribution of both untreated and surface functionalized particles in these suspensions. The influence of particle content on suspension viscosity, aggregate size distribution and that of Ta₂O₅ content on radiopacity was investigated. The shear bond strength of such radiopaque particle-containing adhesives on enamel and dentin was comparable to that of the particle-free reference adhesive.

Conclusions

Flame-made Ta₂O₅/SiO₂ nanoparticles can be introduced readily into dental adhesives as they form quite stable suspensions. Viscosity stayed low even after adding radiopaque particles up to 20wt.%. The resulting composites had radiopacity comparable to that of enamel facilitating their distinction from marginal gaps. Bond strength was not significantly influenced by the presence of particles in the adhesive.

Keywords: Resin, Nanocomposite, Tantalum oxide, Silica, Surface functionalization