In dental medicine endodontics deals with damaged, where after removal of the pulp, the root canals need to be effectively sealed to prevent bacterial infiltration. The discovery of a mineral trioxide aggregate (MTA), a calcium silicate based sealing material (hydraulic cement), was a milestone, since exhibiting excellent sealing abilities and biocompatibility. However, MTA also has drawbacks, since it is based on Portland cement, originally developed for civil engineering, and, thus, containing heavy metal elements, has a long setting time and is difficult to handle. As a result, MTA modifications were designed to improve purity, handling properties and setting time. At the Jožef Stefan Institute, a new multi-component ceramic material called RS+ was recently invented, containing pure calcium trisilicate, zirconium oxide for radiopacity, bioactive glass to enhance biological properties, and finally, bentonite, which improves handling properties. The aim of the thesis was to study the behaviour of RS+ and to prepare a modified version mRS+ with lower amount of bentonite, and to compare their physio-chemical properties. Cements were analysed based on the ISO standard for endodontic sealers. The present work examines the rheological behaviour of the cement paste, and the effect of cement composition on compressive strength and porosity of the hardened cement. The hydration products were analysed using scanning electron microscopy and X-ray diffraction. Finally the effect of calcium chloride addition as hydration accelerator was investigated. Experiments with both tested cement mixtures showed that they have better properties as endodontic sealers compared to classic MTA material. In the comparison between RS+ and the modified version mRS+, it was found that reducing the bentonite content positively affected the desired properties of the sealer.
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