The aim of this study was to synthesis of glass ionomer-silk fiber composite and to evaluate the effect of adding natural degummed silk fiber on the mechanical properties of glass ionomer cement (GIC). For this purpose, natural degummed silk fibers with 1 mm in length and 13-16 µm in diameter were added to the ceramic component of a commercial glass ionomer cement in 1, 3 and 5 wt. %. Compressive strength (CS), three-point flexural strength (FS) and diametral tensile strength (DTS) of the prepared glass ionomer-silk fiber were measured. Analysis of variance (ANOVA) was used to compare the obtained results. Moreover, SEM technique was used for investigation of the surface morphology of as-prepared composite and fractured area. The results showed that the highest compressive strength, flexural strength and diametral tensile strength were obtained using 3, 3 and 5 wt. % of silk fiber, respectively. However, at 3 wt. % silk fiber, all three measures of strength exhibited a significant increase compared to the commercial GIC. Therefore, it can be suggested that the addition of 3 wt. % silk fiber to the ceramic component of GIC is desired for dental restorations and orthopedic implant applications, where the maximum strength in all three modes of loading would be beneficial.
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