Hollow glass fibers in reinforcing glass ionomer cements

This study investigated the reinforcing effect of hollow and solid discontinuous glass fiber fillers with two different loading fractions on select mechanical properties of conventional and resin modified glass ionomer cements (GICs).

Experimental fiber reinforced GIC was prepared by adding discontinuous glass fiber (hollow/solid) of 0.5mm in length to the powder of commercial GICs (GC Fuji IX and II LC) with two different weight ratios (5 and 10wt%) using a high speed mixing machine. Fracture toughness, work of fracture, flexural strength, flexural modulus, compressive strength and diametral tensile strength were determined for each experimental and control material. The specimens (n=7) were wet stored (37°C for one day) before testing. Scanning electron microscopy was used to evaluate the microstructure of the experimental fiber reinforced GICs. Fiber length analysis was carried out to investigate the fiber length distribution of experimental GICs. The results were analyzed statistically using ANOVA followed by Tukey's post hoc test. Level of significance was set at 0.05.

An increase in fracture toughness (280 and 200%) and flexural strength (170 and 140%) of hollow discontinuous glass fiber reinforced (10wt%) conventional and resin modified GICs respectively, were achieved compared to unreinforced materials (p<0.05). Compressive strength did not show any significant differences (p>0.05) between the fiber reinforced and unreinforced GICs.

The use of hollow discontinuous glass fiber fillers with conventional and resin modified GIC matrix is a novel reinforcement. It yielded superior toughening and flexural performance compared to the particulate GICs used.