Marginal seal of resin-modified glass ionomers and compomers: effect of delaying polishing procedure after one-day storage.

This study evaluated the effects of polishing after one-day storage in water on the marginal gap formation around fillings using three resin-modified glass ionomers, one compomer, one conventional glass ionomer, and one micro-filled composite as a control. The study also examined the marginal gap and bond strength in Teflon cavities and the flexural strength of these restorative materials, which may influence the marginal gap formation. Immediately after the setting procedure, the specimen was polished and a marginal gap of approximately 10-25 micrometers was observed regardless of the type of restorative material used. In contrast, we observed no gap or a 1-2 micrometer gap width when the specimens were polished after one-day storage. Only Dyract did not show this pattern. Statistical difference was observed between immediately polishing and polishing after one-day storage in all materials except Dyract. Hygroscopic expansion, bond strength and flexural strength play important roles in reducing the marginal gap in tooth cavities filled with two types of glass-ionomer restorative materials. In contract, these properties did not play important roles in reducing the marginal gap width for Dyract.