Sol-Gel Synthesis and Characterization of YSZ Nanofillers for Dental Cements at Different Temperatures.

Anastasia Beketova,Antonios Anastasiou,Dimitra Kourtidou,Athanasios E Rigos,Liliana Liverani,Marcela Arango Ospina,Anna Theocharidou,Emmanouil-George C Tzanakakis,Ioannis G Tzoutzas,Ioannis Tsamesidis,Eleana Kontonasaki,Georgia K Pouroutzidou

doi:10.3390/dj9110128

Abstract

Background: Yttria-stabilized zirconia nanoparticles can be applied as fillers to improve the mechanical and antibacterial properties of luting cement. The aim of this study was to synthesize yttria-stabilized zirconia nanoparticles by the sol–gel method and to investigate their composition, structure, morphology and biological properties. Methods: Nanopowders of ZrO2 7 wt% Y2O3 (nY-ZrO) were synthesized by the sol–gel method and were sintered at three different temperatures: 800, 1000 and 1200 °C, and their composition, size and morphology were investigated. The biocompatibility was investigated with human gingival fibroblasts (hGFs), while reactive oxygen species (ROS) production was evaluated through fluorescence analysis. Results: All synthesized materials were composed of tetragonal zirconia, while nanopowders sintered at 800 °C and 1000 °C additionally contained 5 and 20 wt% of the cubic phase. By increasing the calcination temperature, the crystalline size of the nanoparticles increased from 12.1 nm for nY-ZrO800 to 47.2 nm for nY-ZrO1200. Nano-sized particles with good dispersion and low agglomeration were received. Cell culture studies with human gingival fibroblasts verified the nanopowders’ biocompatibility and their ROS scavenging activity. Conclusions: the obtained sol–gel derived nanopowders showed suitable properties to be potentially used as nanofillers for dental luting cement.

Highlights

During the final step of the degradation that occurred in the temperature range of 540–900 ◦ C, an exothermic peak appeared at ~628 ◦ C, possibly related to the removal of the element carbon from the final compound [44] and/or a crystalline–amorphous phase transition [33,45]
Dynamic Light Scattering Analysis (DLS) measurements in the present study suggest a moderate to low polydispersity in all samples, as the polydispersity index (PDI) values are below or around 0.3, but the high average nanoparticle diameter calculated may be attributed to the tendency of nanoparticles to assemble in nanoclusters or to the severe distortion of DLS measurements due to nanoparticles polyhedral morphology [66,67]
Pure tetragonal yttria-stabilized zirconia (YSZ) nanopowders with low agglomeration were successfully synthesized by the sol–gel method at different temperatures

Summary

Introduction

Various nanoparticles have been proposed for the reinforcement of different dental materials such as restorative composite materials, glass ionomer cement, dental adhesives and calcium silicate cement. In the last two decades, high purity zirconia (ZrO2 ) nanomaterials gained significant interest in dental technology, as they combine high toughness, high strength and high corrosion resistance with biocompatibility, lack of toxicity and antibacterial properties [1]. Their primary application is in the fabrication of dense polycrystalline zirconia ceramics in the form 4.0/).

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