Microleakage and retention of bonded amalgam restorations.

Purpose: To compare the microleakage and bond strength exhibited by two light-cured, filled dentin bonding agents, a resin cement, and cavity varnish.
Materials and Methods: The four test groups of lining agents for amalgam restorations included (LF) Light-cured, Filled resin (Clearfil Liner Bond 2); (LCF) light- and chemical-cured, Filled resin (Clearfil Liner Bond + Protect Liner); (RC) Resin Cement (Panavia 21); and (V) Varnish (Copalite). For each group, 20 Class V cavity preparations were cut in human extracted molars. Tytin amalgam was condensed into the preparation. After storage for at least 24 hrs in distilled water at 37 degrees C, all restorations were subjected to 2500 thermal cycles (8 degrees C to 48 degrees C). After 1 wk, specimens were tested. For the leakage tests, teeth were immersed in 45Ca, sectioned, and radiographs of sections were evaluated and then evaluated by Ridit analysis. Retention samples were tested to failure in tension using an Instron machine and peak load (kg) was recorded.
Results: Compared to varnish, the two dentin bonding agents (LF and LCF) significantly decreased microleakage at the cementum margin but not at the enamel margin. The two dentin bonding agents also exhibited significantly greater retentive strength than either the resin cement or the varnish.