Microleakage in various dentin bonding agent/composite resin systems.

One important consideration in the selection of a dentin bonding agent/composite resin system is its resistance to marginal leakage. The purpose of this study was to compare both the extent and the pathways of marginal leakage for four currently available dentin bonding agent/composite resin systems. Class 5 restorations were placed in the buccal and lingual surfaces of 20 extracted human teeth. Specimens were subjected to thermal stress before being placed in silver nitrate solution. They were then sectioned longitudinally and observed under a light microscope. Selected samples were further studied using scanning electron microscopy (SEM) and energy-dispersive x-ray analysis (EDX). Different systems exhibited different leakage patterns. Findings suggest that the smear layer should be either conditioned or removed prior to dentin bonding agent application to provide optimal resistance to microleakage.