Methods: The materials studied were a giomer (Beautifil II [BF]), two compomers (Compoglass F [CF] and F2000 [F2]), a resin-modified light-cured glass ionomer cement (Photac Fil Quick Aplicap [PH]) and a glass-ionomer cement (FX-II, [FX]). Fourty-eight specimens for each material were produced according to manufacturers' instructions. They were then conditioned in distilled water (DW, control group), citric acid of pH 5 (CA5) and citric acid of pH 3 (CA3) at 37°C for 1, 7, 14 and 28 days. After conditioning, the materials were subjected to shear punch testing using a 2mm diameter punch at a crosshead speed of 0.5mm/minute. The mean shear strengths were subjected to ANOVA/Scheffe's test at 0.05 significance level.
Results: For all time internals, BF and CF showed significantly higher shear punch strength values compared to other materials evaluated. pH had significantly lower shear punch strength values after conditioning in CA3.
Conclusion: The effects of pH on shear punch strength were material dependent.