Diametral tensile strength of two Brazilian resin-modified glass ionomers cements: influence of the powder/liquid ratio

The aim of this study was to evaluate the influence of powder/liquid ratio in the diametral tensile strength of two resin-modified glass ionomers cements (RMGIC). Two Brazilian brands of RMGIC: Resiglass R (RG: Biodinâmica) and Vitro Fil LC (VF: DFL) were used. Each product was mixed in two different powder/liquid ratios, (1:1) 1 scoop of powder to one drop of liquid or (1:2) 1 scoop of powder to 2 drops of liquid. The control was considered the powder/ liquid ratio recommended by each manufacturer (RG 1:1 and VF 1:2 P/L). Four groups (n=5) with sample dimensions of 2.5 and 5.0 mm (thickness and diameter respectively) were tested. Diametral Tensile Test was performed in a mechanical testing machine (EMIC DL 500). Data obtained were submitted to One-way ANOVA and Tukey’s multiple comparisons test (α=5%). For both national RMGICs, the experimental variations in the powder/liquid ratio led to an increase in diametral tensile strength when compared to the ratios advocated by the manufacturers. Group VL manipulated with experimental ratio 1:1 showed statistically the highest (25.54±2.38 MPa) DTS mean among the tested groups whereas Resinglass R manipulated with 1:1 ratio, as advocated by manufacturer, showed statistically the lowest DTS mean (9.27±1.37 MPa). A review and further adjustments in the ratios recommended by the manufacturers of both resin-modified glass ionomers cements investigated is necessary.