Abstract
The aim of the study was to evaluate the effects of incorporation of Al2O3, ZrO2 and TiO2 nanoparticles into glass–ionomer cements (GICs). Two different GICs were used in the study. Four groups were prepared for each material: the control group (without nanoparticles) and three groups modified by the incorporation of nanoparticles at 2, 5 or 10 wt %, respectively. Cements were mixed and placed in moulds (4 mm × 6 mm); after setting, the samples were stored in saline (one day and one week). Compressive strengths were measured and the morphology of the fractured surfaces was analyzed by scanning electron microscopy. The elements released into the storage solutions were determined by Inductively coupled plasma-optical emission spectrometry (ICP-OES). Addition of nanoparticles was found to alter the appearance of cements as examined by scanning electron microscopy. Compressive strength increased with the addition of ZrO2 and especially TiO2 nanoparticles, whereas the addition of Al2O3 nanoparticles generally weakened the cements. The ion release profile of the modified cements was the same in all cases. The addition of Al2O3, ZrO2 and TiO2 nanoparticles into GICs is beneficial, since it leads to reduction of the microscopic voids in the set cement. Of these, the use of ZrO2 and TiO2 nanoparticles also led to increased compressive strength. Nanoparticles did not release detectable levels of ions (Al, Zr or Ti), which makes them suitable for clinical use.
Highlights
Glass ionomer cements (GICs) are widely used dental restorative materials, especially in paediatric dentistry
Compressive strength values varied according to the particular brand of glass–ionomer cement, the chemical composition of the nanoparticles, the loading of nanoparticles and the storage time (Figure 1)
Similar results were obtained with ChemFil® Rock, but the results shown in the microphotographs (Figure 4A,B, and Figure 5A,B) demonstrate that the greatest reduction in porosity occurred following addition of 5% of Al2 O3, ZrO2, TiO2
Summary
Glass ionomer (polyalkenoate) cements (GICs) are widely used dental restorative materials, especially in paediatric dentistry. Glass–ionomer cements consist of calcium or strontium alumino-fluoro-silicate glass powder (base) that is combined with a water-soluble acidic polymer. When these components are mixed together, they undergo an acid–base (neutralisation) setting reaction to form a hardened material [1]. Materials 2020, 13, 276 any loss of physical properties of the hardened cement, significant amounts of fluoride ions are released from this material, a property which is crucial for their anticariogenicity, which is one of the advantages of these materials Another major advantage of GIC is its ability to chemically bond to dentin and enamel and to form an acid resistant interface with these substrates [6]. Glass–ionomers have been described as bioactive materials due to the exchange of ions with the tooth surface [7]
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