Biophysical characterization of functionalized titania nanoparticles and their application in dental adhesives.
It is demonstrated that carboxylic acid-functionalized titanium dioxide (TiO2) NPs produce significantly higher levels of reactive oxygen species (ROS) after visible light irradiation (400-800nm, 1600mW/cm2) in comparison to nonfunctionalized TiO2NPs. The level of ROS produced under these irradiation conditions was not capable of generating oxidatively induced DNA damage in a cell-free system for TiO2concentrations of 0.5mg/L or 5mg/L. In addition, specific incorporation of the acrylic acid-functionalized TiO2NPs into dental composites allowed us to utilize the generated ROS to enhance photopolymerization (curing and degree of vinyl conversion (DC)) of resin adhesives and create mechanically superior and biocompatible materials for dental applications. Incorporation of the TiO2NPs into selected dental composites increased the mean DC values by ≈7%. The modified TiO2materials and dental composite materials were extensively characterized using thermogravimetric analysis, electron microscopy, Fourier transform infrared spectroscopy, and electron paramagnetic resonance. Notably, dental adhesives incorporated with acrylic acid-functionalized TiO2NPs produced stronger bonds to human teeth following visible light curing in comparison to traditional dental adhesives not containing NPs with an increase in the shear bond strength of ≈29%. In addition, no leaching of the incorporated NPs was detectable from the dental adhesives after 2500 thermal cycles using inductively coupled plasma-optical emission spectroscopy, indicating that biocompatibility of the adhesives was not compromised after extensive aging. These findings suggest that NP-induced ROS may be useful to produce enhanced nanocomposite materials for selected applications in the medical device field.



Titanium dioxide nanoparticles (TiO2NPs) have unique photocatalytic, antibacterial and UV-absorbing properties that make them beneficial additives in adhesives and composites. However, there is concern that the reactive oxygen species (ROS) produced by photoactivated TiO2NPs might pose toxicological risks. We demonstrate that it is possible to incorporate acid-functionalized TiO2NPs into dental resins which can be applied as dental adhesives to human teeth. The ROS generated by these NPs through visible-light irradiation may be utilized to increase the degree of vinyl conversion of resins, leading to adhesives that have an enhanced shear-bond strength to human teeth. Investigation into the potential genotoxicity of the NPs and their potential for release from dental composites indicated a low risk of genotoxic effects.
Volpe Research Center, American Dental Association Foundation, Gaithersburg, MD 20899, USA. Electronic address: jirun.sun@nist.gov.
Jirun
J
Sun
Cell Systems Science Group, Biosystems and Biomaterials Division, Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
Elijah J
EJ
Petersen
Polymeric Materials Group, Materials and Structural Systems Division, Engineering Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
Stephanie S
SS
Watson
Cell Systems Science Group, Biosystems and Biomaterials Division, Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
Christopher M
CM
Sims
Volpe Research Center, American Dental Association Foundation, Gaithersburg, MD 20899, USA.
Alexander
A
Kassman
Volpe Research Center, American Dental Association Foundation, Gaithersburg, MD 20899, USA.
Stanislav
S
Frukhtbeyn
Volpe Research Center, American Dental Association Foundation, Gaithersburg, MD 20899, USA.
Drago
D
Skrtic
Cell Systems Science Group, Biosystems and Biomaterials Division, Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
Meryem T
MT
Ok
Polymeric Materials Group, Materials and Structural Systems Division, Engineering Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
Debbie S
DS
Jacobs
Cell Systems Science Group, Biosystems and Biomaterials Division, Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
Vytas
V
Reipa
Bioengineering Research Center, University of Kansas, Lawrence, KS 66045, USA.
Qiang
Q
Ye
Cell Systems Science Group, Biosystems and Biomaterials Division, Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA. Electronic address: bryant.nelson@nist.gov.
Bryant C
BC
Nelson
D000268:Adhesiveness; D003738:Dental Cements / Q000737:chemistry* / Q000528:radiation effects; D006244:Hardness; D008027:Light; D055115:Light-Curing of Dental Adhesives / Q000379:methods*; D008422:Materials Testing; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D017382:Reactive Oxygen Species / Q000138:chemical synthesis*; D014025:Titanium / Q000737:chemistry*; D014070:Tooth / Q000737:chemistry*
D003738:Dental Cements; D017382:Reactive Oxygen Species; C009495:titanium dioxide; D014025:Titanium
DNA damage; Dental resins; Nanoparticles; Reactive oxygen species; Titanium dioxide