Microleakage in alloy-glass ionomer lined amalgam restorations after thermocycling

Marginal microleakage was measured around amalgam restorations lined with alloy-glass ionomer cement and coated with a glass ionomer varnish. Preparations were made in 48 human extracted mandibular molar teeth. Alloy-glass ionomer liners and varnishes were placed into selected preparations. Tytin amalgam was inserted into all of the teeth and left unburnished and unpolished. Half of the total samples were thermocycled for 5 days and the remainder were left in deionized water. The teeth were immersed in a 0.5% methylene blue dye and sectioned vertically with a diamond saw. Microleakage was scored visually at x100 magnification, and the data were analysed using the Mann-Whitney U-test (P less than or equal to 0.05). Thermocycling did not have a significant effect on microleakage, except when both an alloy-glass ionomer liner and varnish were used. Overall, the use of an alloy-glass ionomer liner made the most significant difference in reducing microleakage.