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# Effect of cation substitutions in an ionomer glass composition on the setting reaction and properties of the resulting glass ionomer cements

A. M. P. Kashani, Mitra (2013)
Ph.D. thesis, University of Birmingham.

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## Abstract

This study investigated the effect of Ba$$^2$$$$^+$$ and Sr$$^2$$$$^+$$ substitutions for Ca$$^2$$$$^+$$ in an ionomer glass composition 4.5SiO$$_2$$-3Al$$_2$$O$$_3$$-1.5P$$_2$$O$$_5$$-3CaO-2CaF$$_2$$ on the setting reaction and properties of the resulting glass ionomer cements (GICs). Experimental GICs (Ca-GIC, Ca-Sr-GIC and Ca-Ba-GIC) were characterized via various techniques: Diametral tensile strength, compressive strength, flexural strength, Vickers hardness and nano-indentation measurements were conducted at different time points during setting. Real time Fourier transform infrared (FTIR) spectroscopy was used to study the effect of the glass composition on cement setting reactions. A resistance to penetration method evaluated the cement setting time. Additionally, the wear resistance of the experimental GIC was measured by a ball-on-flat wear test. Furthermore, fluoride (F$$^-$$) release and the antimicrobial behaviour of cements were investigated. The compressive, diametral and flexural strength of the cements in which Ca$$^2$$$$^+$$ was substituted by Sr$$^2$$$$^+$$ and Ba$$^2$$$$^+$$ were both statistically significantly higher than the unsubstituted control at 1 hour after setting (P < 0.001). FTIR results confirmed that enhanced metal salt crosslinking occurred in the ion substituted materials, especially from 1 to 60 minutes. Therefore, it can be concluded that replacing Ca$$^2$$$$^+$$ with larger cations (Sr$$^2$$$$^+$$ and Ba$$^2$$$$^+$$) affects the setting reaction and resulting mechanical properties in the short term. All three experimental GICs inhibited growth of Streptococcus mutans over a period of 48 hours. The F$$^-$$release analysis showed that there was less F$$^-$$ release in artificial saliva (AS) than in deionized water over 40 days.

Type of Work: Ph.D. thesis. Stamboulis, Artemis Colleges (2008 onwards) > College of Engineering & Physical Sciences School of Metallurgy and Materials RK Dentistry University of Birmingham 4548
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