Acid-Mediated Wear of Glass Ionomers as a Function of Temperature

Methods: 32 specimens of Ketac Molar, ChemFil Molar, Fuji IX Extra and Diamond Carve GICs were prepared according to manufacturers' instructions and packed into silicone molds set against a glass slab to provide a flat surface with an intervening sheet of acetate to prevent the GIC from adhering to the glass. 32 specimens of bovine enamel were sectioned, mounted in resin and polished using silicon carbide paper to 1200 grit to create a flat surface. Control areas were masked with adhesive tape and specimens were exposed to 0.3% pH3.2 citric acid monohydrate at 4, 25, 37 or 60°C, stirred at 0.25m/s for 60min. Wear was recorded using an optical profilometer (Proscan 2000, Scantron). Results: All specimens exhibited statistically significant wear at all temperatures. Wear significantly increased with temperature for all GICs and enamel. Enamel exhibited more wear than any of the GICs at all temperatures, by a factor of 2-6x. There were few statistically significant differences between the different GICs.

Conclusions: GICs are prone to acid-mediated dissolution and this process is more rapid at elevated temperatures. None of the GICs investigated had any clear advantage over any other in this regard. Although GIC wear proceeds more slowly than that of enamel, dentists and patients ought to be aware that GICs used to repair erosive lesions are prone to erosion themselves, and that the destruction of the GIC is more rapid in warm solutions.