Repair or correction of a glass ionomer cement (G1C) restoration contour would occasionally require additions to an existing restoration using the available GIC which could be the same or a different brand. Three brands of light-cured restorative GICs were used to fabricate cylindrical specimens consisting of two equal halves each. To simulate repair of aged restorations, specimens first halves were fabricated and then aged in water at 37"C for one month. They were divided into two groups for surface treatment for 15 sec using 25% polyacrylic acid in one group and a slurry of pumice on a rubber cup in the other group. Specimens "second halves were then built up against the treated surfaces using combinations of GICs. To simulate immediate repair, the specimens second halves were immediately built up of the same GIC against untreated surfaces of the first halves. Specimens simulating unrepaired restorations were fabricated and used as controls. Shear bond strengths were determined using universal testing machine after storage of all specimens in water at 37°C for one hour. Results showed, in general, a slight decrease in repair bond strength of GICs compared to the cohesive strength of unrepaired ones. Shear bond strengths of immediate repairs were higher than those for repaired aged GICs, and significantly higher for one brand. No significant differences in shear strength were found among the repaired aged GICs when brand combinations and surface treatments were used. The objective of this study, therefore, was to investigate the effect of repair time, GIC brand combination and surface treatment on the repair bond strength of resin-modified restorative GICs.

Saudi Dental Journal 1997;9(2):83-89.