Review of nanomaterials in dentistry: interactions with the oral microenvironment, clinical applications, hazards, and benefits.

Interest in the use of engineered nanomaterials (ENMs) as either nanomedicines or dental materials/devices in clinical dentistry is growing. This review aims to detail the ultrafine structure, chemical composition, and reactivity of dental tissues in the context of interactions with ENMs, including the saliva, pellicle layer, and oral biofilm; then describes the applications of ENMs in dentistry in context with beneficial clinical outcomes versus potential risks. The flow rate and quality of saliva are likely to influence the behavior of ENMs in the oral cavity, but how the protein corona formed on the ENMs will alter bioavailability, or interact with the structure and proteins of the pellicle layer, as well as microbes in the biofilm, remains unclear. The tooth enamel is a dense crystalline structure that is likely to act as a barrier to ENM penetration, but underlying dentinal tubules are not. Consequently, ENMs may be used to strengthen dentine or regenerate pulp tissue. ENMs have dental applications as antibacterials for infection control, as nanofillers to improve the mechanical and bioactive properties of restoration materials, and as novel coatings on dental implants. Dentifrices and some related personal care products are already available for oral health applications. Overall, the clinical benefits generally outweigh the hazards of using ENMs in the oral cavity, and the latter should not prevent the responsible innovation of nanotechnology in dentistry. However, the clinical safety regulations for dental materials have not been specifically updated for ENMs, and some guidance on occupational health for practitioners is also needed. Knowledge gaps for future research include the formation of protein corona in the oral cavity, ENM diffusion through clinically relevant biofilms, and mechanistic investigations on how ENMs strengthen the tooth structure

Preparation of Mg-doped ZnO nanoparticles by mechanical milling and their optical properties

AbstractMg-doped ZnO nanoparticles were synthesized by planetary ball milling at a speed of 400rpm and milled for 20h. The samples were characterized by XRD, SEM and UV-Vis spectrophotometer. The crystallite size of the samples increased and the lattice strain decreased with an increase of MgO loading. The increase in crystallite size of the samples as a function of MgO loading can be explained by the effect of Ostwald ripening. The absorption edge of the samples shifted to a lower wavelength when MgO loading was increased. The energy band gap of the samples varied in a range of 2.96-3.13eV depending on the loading content

Synthèse et caractérisation de ZnO nanométrique par la méthode chimie douce

Nous avons synthétisé des matériaux nanostructurés de ZnO par différentes voies de chimie douce, c est-à-dire, par les méthodes sol-gel et pyrolsol. Cette recherche a consisté à étudier et mettre au point les paramètres expérimentaux qui influencent les propriétés structurales de ZnO tel que la nature du précurseur, du complexant ou du stabilisateur, leurs concentrations et, quand c est le cas, la concentration en dopant. Les paramètres thermiques comme la température de réaction et la température de traitement thermique ont aussi été optimisés. Les matériaux de ZnO contenant du chrome et de l aluminium ont également été étudiés. Les couches minces de ZnO non dopé préparées par le méthode dip coating sur substrat de verre ont donné dans les meilleurs cas des tailles d environ 40 nm. Pour le matériau dopé, ZnO :Al, 10at% Al, les particules atteigne des dimensions d environ 5 nm. Pour les couches minces préparées par la méthode pyrosol, la plus petite taille obtenue de ZnO non dopé est d environ 70 nm et pour ZnO :Al, 5at% Al, les tailles sont d environ 90 nm. Enfin, les nanoparticules de ZnO obtenues par précipitation des solutions présentent des taille d environ 10 nm. Des poudres de CrxZn1-xO nanométriques où x est 0.05, 0.10 et 0.15, présentent un comportement ferromagnétique faible avec la température par les méthodes de DXR, MET et MEB de couplage de ces différents méthodes physiques à permis d apporter de conclusion sur les méthode d élaboration par chimie douceWe have synthesized nanostructured ZnO materials by various ways of soft chemistry techniques, i.e. sol-gel and pyrosol methods. This research has consisted to study and develop the experiment parameters which influence the structural properties of nanostructured ZnO such as nature of precursor, complexing agent or stabilizer, precursor and dopant concentration. The thermal parameters such as reaction temperature and heat treatment temperature have been optimized as well. The ZnO materials containing of chromium and aluminium have also been studied. The undoped ZnO thin films prepared by dip coating on glass substrate give, in the best case, the approximate size 40 nm. In case of doped ZnO material, ZnO:Al, 10 at.% Al, the sizes reach approximate 5 nm. The ZnO thin films are prepared by pyrosol method giving the smallest size of undoped ZnO about 70 nm and ZnO:Al, 5 at.% Al about 90 nm. Lastly, the ZnO nanoparticles are prepared by precipitation giving the smallest size about 10 nm. The nanocrystalline CrxZn1-xO powders where x is 0.05, 0.10 and 0.15, have exhibited a weak ferromagnetic behavior with Curie temperature of 0.6, 2.6 and 7.1 K, respectivelyMONTPELLIER-BU Sciences (341722106) / SudocSudocFranceF