Biocompatibility and nanotoxicology of titanium dioxide in the oral cavity: Systematic review.

The aim of the present review article was to analyze the biological impact and toxicology of titanium dioxide nanoparticles (TiO2 NPs) to determine their cytotoxicity, reactive oxygen species production as well as induction of oxidative stress through a systematic review of the literature published so far about the biocompatibility of TiO2 NPs in contact with oral cells. Available data on nanoparticles (NPs) were collected from the PubMed and Science Direct electronic databases, and other sources according to PRISMA recommendations for systematic reviews. In the qualitative analysis of published data on cytotoxicity in oral cells, a slight increase in the number of metabolically active cells has been observed when the TiO2 NPs are in contact with oral cells; however, at certain doses cellular viability decreases significantly. One of the negative effects of NPs is the induction of prostaglandin E-2 production in a previous pro-inflammatory state, which could increase the existing inflammatory effect. Therefore, the biological application of these nanoparticles must be performed both in vivo and metabolomic studies, since it is possible that the results of the in vitro experiments cannot be extrapolated to an in vivo system, since it been observed that the particles tend to aggregated among them, in the culture medium, used for such as tests. Therefore, although it can be considered a material with light or even biocompatible cytotoxicity, it must not be considered completely harmless.