Characterization of glass ionomer cements stored in various solutions

Abstract

© 2019 Materials and technology. The aim of this work was to evaluate the nano-mechanical properties of glass ionomer materials, the ion concentrations at the surfaces in relation to the storage media and the pH environments using a scanning electron microscope with an energy-dispersive spectrometer (SEM/EDX). The glass-ionomer-based materials, Fuji Triage (FT), Fuji VIII (FVIII), Fuji IX GP (FIX), were analyzed. The sample comprised 45 cured cement disks. Five specimens of each tested material were placed in 3 storage solutions (saline, acidic solution with pH of 5.5, NaF solution with 0.05 % of fluoride). Nano-indentations were performed with a force up to 30 mN, penetration depths of 2500-2700 nm for 1 d and 21 d after setting. The EDX evaluation was carried out for each experimental disk, identifying the ions: O, Al, Sr, Si, F, Na, P, Ca. The level of significance was placed at p < 0.05.The highest fluoride proportion at the specimen surface was recorded in the FT material. FT also exhibited the lowest fluoride ions content when stored in low-pH environments compared with the other tested materials (p < 0.05). The surface hardness of the tested materials decreased from 1.377 GPa (in saline) to 0.03 GPa (in acid). The Young's modulus varied from 14.35 GPa to 0.112 GPa, depending on the material type (Fuji VIII > Fuji IX > FT) (p < 0.001) and the storage media (p < 0.001). Both the mechanical and cariostatic surface properties of commercially available glass ionomer materials are affected by the storage media.