The Influence of Mixing Methods on the Compressive Strength and Fluoride Release of Conventional and Resin-Modified Glass Ionomer Cements

Abstract

Objective. To evaluate the compressive strength and fluoride ion release of conventional and resin-modified glass ionomer cement mixing methods (hand mix and mechanical mix) compared to ready-to-use ones. Materials and Methods. Two conventional glass ionomer cements (GICs) (Fuji II and Fuji II Caps), two resin-modified GICs (Fuji II LC and Fuji II L Caps), and one ready-to-use GIC (Ionoseal, Voco) were used. For the compressive strength test, cylindrical specimens (6 mm × 4 mm) of each group were prepared. The test was performed in a universal testing machine (EMIC DL2000). For the fluoride release test, specimens were prepared in the form of discs and placed in deionized/distilled water, which were replaced daily for 15 days. The fluoride ion release readings were performed on an electrode (Orion 96-09) connected to a digital ion analyzer (Quimis 0400ISE). The compressive strength data were analyzed with one-way ANOVA, and the ion release data were submitted to repeated measures ANOVA (material vs. time) and Holm–Sidak post test (α = 5%). Results. The one-way ANOVA showed statistical difference between the tested materials (p<0.001). Ionoseal showed the highest values of compressive strength (p<0.001). Mechanical manipulation increased the compressive strength only for conventional GIC, and resin-modified GIC did not present any statistical difference. Conventional GIC (mechanical mix) showed higher fluoride release on first day than the other groups tested. Conclusion. There was influence of the mixing methods of the materials on the compressive strength and fluoride release pattern of the glass ionomer cements.