Nanotechnology

Nanotechnology uses nanosized particles and surface features with very high ratios of surface area to volume that are usually different in their bioactivity, solubility, and antimicrobial effects compared with larger particles of the same composition. Thus changes in properties cannot be extrapolated by an inverse linear analysis of particle size but must be determined through in vitro and in vivo testing of the nanomaterials. In dentistry, nanotechnology had been focused on the development of nanoparticle fillers to improve dental composite esthetics. The use of nanotechnology today is more diverse.

In biomimetics, nanotechnology is being used to develop materials that promote hard tissue remineralization. Biomimetic materials and processes mimic those that occur in nature, particularly self-assembly of components to form, replace, or repair oral tissues. These concepts are discussed further later in this chapter.

For dental implants and related devices, nanoparticles are used to modify dental implant surfaces to influence the host response at the cellular and tissue levels. Electrophoretic sol-gel fabrication, pulsed laser deposition, sputter coating, and ion-beamassisted deposition are among the approaches used to develop nanotextured, thin-film, biocompatible coatings for implant surfaces. These technologies reduce the thickness of the coating layer and increase the specific surface area and reactivity to improve the interaction with the surrounding apical tissue.

Important nanoparticles include metals, such as silver, and ceramic powders, such as silica and titanium dioxide. In situgenerated silver nanoparticles have been reported to be highly effective in restorative resins, bonding resins, and prosthetic resins for inhibiting a variety of biofilm-forming bacteria while not interfering with manipulation, curing, mechanical properties, or other performance properties. Silica nanoparticles already have wide use in dentistry, from toothpastes to composites. Titania nanoparticles are widely used for pigments in dental materials but lack the stronger antimicrobial effects of Ag.

Another recently introduced nanotechnology kills bacteria on contact on restoration surfaces. Infinix flowable composite (Nobio Ltd., Israel), which contains quaternary ammonium bound to silica (also known asQASi) was reported to significantly reduceEnterococcus faecalis on the surface of the material without affecting composite flexural strength, radiopacity, depth of cure, water sorption, or water solubility. After 6 and 12 months of use in vivo, there was a 50% reduction of live bacteria on Nobio QASi composites compared with control composites. An added advantage of the QASi-containing surfaces is that no recharging is needed, unlike the fluoride in glass ionomers that confers microbial resistance. Prevention of bacterial biofilm protects the integrity of the dental product restorations.

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Nanotechnology - an overview | ScienceDirect Topics