ABSTRACT
Although the incorporation of bioactive glasses into glass ionomer cements (GICs) has led to promising results, using a bioactive glass as the only solid component of GICs has never been investigated. In this study, we developed an Al-free GIC with standard compressive strength using various combinations of 45S5 Bioglass® and its glass-ceramic as the solid component. The glass-ceramic particles with 74% crystallinity were used for this purpose as they can best act as both remineralizing and reinforcing agents. Strengthening mechanisms including crack deflection and crack-tip shielding were activated for the GICs containing 50-50 wt% bioglass and bioglass-ceramic as the optimum ratio. The progression of the GIC setting reaction at its early stages was also monitored and verified. We also discussed that our bimodal particle size distribution containing both micron- and nanosized particles may enhance the packing density and integrity of the structure of the cements after setting. In such GICs produced in this study, the toxic effects of Al are avoided while chemical bonds are expected to form between the cement and the surrounding hard tissue(s) through interfacial biomineralization and adhesion.
Subject(s)
Aluminum/chemistry , Ceramics/chemistry , Glass Ionomer Cements/chemistry , Bone Cements , Compressive Strength , Glass/chemistry , Hardness , In Vitro Techniques , Materials Testing , Nanoparticles/chemistry , Particle Size , Powders , Spectroscopy, Fourier Transform Infrared , Stress, Mechanical , Surface Properties , Tensile Strength , X-Ray DiffractionABSTRACT
The clinical applications of glass ionomer cements (GICs) are limited by their relatively poor mechanical properties and insufficient remineralizing capacity. In this study, we developed hybrid GICs with improved mechanical and remineralizing properties via incorporation of an optimum amount (5â¯wt%) of 45S5 bioglass-ceramic particles. Also, we found that bioglass-ceramic particles with 74% crystallinity best act as both remineralizing and reinforcing agents. The degree of crystallinity of the additives, is overlooked in this context in other research. At around 74% crystallinity, there is sufficient amount of combeite and an amorphous phosphorous-rich phase in the 45S5 bioglass-ceramic particles to respectively promote their reinforcing role and allow them to effectively partake in the setting process creating an excellent interfacial bond with the GIC matrix. As a result, several strengthening mechanisms such as crack deflection and crack-tip shielding are activated within the hybrid GIC containing 5â¯wt% bioglass-ceramic with 74% crystallinity, contributing to its improved mechanical properties. The enhanced remineralizing and mechanical properties of such hybrid GICs can potentially improve their in vivo performance and broaden their clinical applications.
