SummaryThe aim of this study was to compare the effects upon marginal leakage of a number of dentine bonding agents when used with a posterior composite resin, Occlusin, after storage for periods of up to 2 years. The bonding agents used were Gluma, Scotchbond, Topaz and an experimental material. The results were compared with a glass ionomer, Chemfil II. Class V cavities with or without a bevelled cavo‐surface margin were prepared in the buccal surfaces of extracted premolar teeth. Following restoration, the teeth were stored for periods of up to 2 years and then thermally cycled. Marginal leakage was subsequently demonstrated using a radioactive isotope containing45Ca, and an auto‐radiographic technique. Image analysis was used to determine the total amount of linear leakage for each specimen. The results showed that some leakage occurred for all materials at each time interval. The bevelled design of cavity allowed significantly less leakage than the unbevelled cavity. Overall, there was little difference between the various dentine bonding agents. The glass ionomer restorations showed significantly less leakage than the composite resin and dentine bonding agent combinations in unbevelled cavit