Effect of water on shear strength of glass ionomer cements for luting.

This study examined the effect of ambient water on the shear strength of glass ionomer cements for luting. Disk specimens were fabricated from four commercially available glass ionomer cements with different setting modes. At one hour after the start of mixing, the specimens were stored at 37 degrees C for 24 and 168 hours in dry condition or in deionized water. Shear strength was then determined using a punch tool. The shear strengths of both conventional cements were significantly greater for the specimens stored dry as compared to those kept in deionized water (p < 0.05). Conversely, resin-modified cement specimens stored dry had significantly lower strength compared to the specimens kept in deionized water (p < 0.05). This was because the ambient water surrounding the resin-modified glass ionomer cements helped increase the shear strength of the cements under the experimental conditions tested.