Comparison of flexural strength among six available restorative glass ionomer cements in Iran

There are several glass-ionomer cements available in the Iranian market. However, no sufficient information is available on mechanical properties of these materials. Therefor, this study was designed in order to investigate the flexural strength of conventional glass-ionomer cements; the Fuji II (Fu II), Kavitan plus (Kp), Securafil (SF) as well as two Resin modified glass–Ionomer cements: The Fuji II Lc (Fu II Lc), Kavitan Lc (K Lc) and two newly developed glass poly phosphonate cements: Diamond carve & 90 (DC & 90) were evaluated. The method used in this investigation was based on the standards of Iso 4049 (1988) and BS 5199 (1989) for resin–based filling materials. The test specimens of 25mm (length) X 2mm (width), and 2mm thickness were prepared. About fifteen minutes after the setting time, the specimens were removed from the mould and then immersed in water and stored at 37°C, until the testing time started. Three points flexural strength were determined with universal testing machine (0.02N, 1mm/s) at 1 day, 1 week and 1 month after the start of the mixing time. The tow-way analysis of variance was conducted in order to determine the effect of two variants of time and substance type on flexural strength. Group differences were analyzed using one way ANOVA and Tukey HSD tests. Fu II Lc showed significantly higher flexural strength at all three testing intervals compared to other materials. After 1 day, DC & 90 became stronger than Fu II, but weaker than Fu II Lc. The strength of these cements was comparable to other conventional cements after 1 week and 1 month. There was no significant difference between the flexural strength of the three conventional cements at three testing periods. The flexural strength of KLc at 1 day and 1 month was lower than Fu II Lc and it was comparable to conventional cements at 1 month. The conventional cements in this study showed similar strengths. Flexural strength of DC & 90 was comparable to conventional cements.