Radiopaque dental adhesives: dispersion of flame-made Ta2O5/SiO2 nanoparticles in methacrylic matrices.
OBJECTIVE
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 gamma-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 20 wt.%. 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.
Department of Mechanical and Process Engineering, ETH Zurich, Switzerland.
Heiko
H
Schulz
Bjoern
B
Schimmoeller
Sotiris E
SE
Pratsinis
Ulrich
U
Salz
Thorsten
T
Bock
D002498:Centrifugation; D003287:Contrast Media / Q000737:chemistry*; D001840:Dental Bonding; D003743:Dental Enamel / Q000648:ultrastructure; D003804:Dentin / Q000648:ultrastructure; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D006358:Hot Temperature; D006801:Humans; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry*; D046529:Microscopy, Electron, Transmission; D053758:Nanoparticles / Q000737:chemistry*; D009584:Nitrogen; D010087:Oxides / Q000737:chemistry*; D010316:Particle Size; D019279:Resin Cements / Q000737:chemistry; D033081:Shear Strength; D012821:Silanes / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry*; D013635:Tantalum / Q000737:chemistry*; D014465:Ultrasonics; D014783:Viscosity; D014961:X-Ray Diffraction
D003287:Contrast Media; D017220:Dentin-Bonding Agents; D008689:Methacrylates; D010087:Oxides; D019279:Resin Cements; D012821:Silanes; C017492:methacryloxypropyltrimethoxysilane; D013635:Tantalum; D012822:Silicon Dioxide; D009584:Nitrogen; C078151:tantalum oxide