Microleakage of amalgam restorations using dentin bonding system primers

To evaluate and compare in vitro microleakage of etched and non-etched Class I amalgam restorations lined with various dentin bonding system primers to amalgam restorations with or without a Copalite liner.

Class I amalgam preparations were made in 140 extracted molars and divided into 14 groups of 10 teeth each. Permite C dispersed phase alloy restorations were placed after the following treatments: Group 1: No liner; Group 2: Lined with two coats of Copalite; Group 3(A): Lined with Amalgambond AA and 3(B): Etched with 35% Ultra-etch and lined with Amalgambond AA; Group 4(A): Lined with Scotchbond Multi-Purpose Primer and 4(B): Etched and lined with the primer; Group 5(A): Lined with ProBond and 5(B): Etched and lined with the primer; Group 6(A): Lined with All-Bond 2 Primer A & B and 6(B): Etched and lined with the primer; Group 7(A): Lined with OptiBond and 7(B): Etched and lined with the primer; Group 8(A): Lined with Permagen Primer and 8(B): Etched and lined with the primer. All primers were applied per manufacturers' specifications. After storage in water for 24 hours, all restorations were polished and then aged in water at 37 degrees C for 90 days. The specimens were then thermocycled for 300 cycles at 5 degrees C and 55 degrees C in basic fuchsin dye with a 30-second dwell time, mounted in epoxy rings, sectioned longitudinally, mesiodistally and buccolingually into four sections, then evaluated at x100 and the extent of dye penetration at the tooth/amalgam interface scored (two scores for each section, eight for each specimen).

The unlined and Copalite-lined groups and all non-etched groups showed considerable marginal leakage. All the etched restorations were significantly more effective in reducing microleakage than the non-etched, no liner and Copalite-lined groups. Etching prior to application of the primers is significantly more effective than nonetching, however the effectiveness of the primer alone to seal the dentin needs to be evaluated. Overall, Amalgam-bond AA had the least microleakage of all the groups.