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

Nurses' perceptions of aids and obstacles to the provision of optimal end of life care in ICU

Contains fulltext : 172380.pdf (publisher's version ) (Open Access

Verb movement in Germanic and Celtic languages: a flexible approach

This paper develops a new perspective on the question of what type of verb movement the modern Celtic languages display, V to I movement or V to C movement. Under the standard assumption that the subject remains relatively low in these languages compared to Germanic languages, this category fails to be a diagnostic, since both verb movement operations cross the subject. The analysis presented here starts from the theory of verb movement developed in Koeneman (2000), which argues that the verb does not move to prefabricated functional head positions but moves in order to project one or more of its functional features (tense and agreement). It is shown how this theory offers a better understanding of verb movement (parameters) than mainstream approaches. After developing a concrete proposal for verb movement variation in Germanic, the paper tries to extend this analysis to the Celtic languages, so that a uniform analysis of verb movement (variation) ensues. The main conclusion is that it is very unlikely that Celtic languages have a verb movement operation involving an agreement projection. They are better analyzed as having a verb movement operation that projects tense features. The result is that the nature of verb movement in Germanic and Celtic is basically the same