Effect of Application of Bonding Agent and Amalgam Setting on Microleakage at the Amalgam-Composite Interface

Background and Objectives: This study aimed to assess the effect of application of bonding agent and amalgam setting on microleakage at the amalgam-composite interface in teeth restored with the sandwich technique. Materials and Methods: This in vitro, experimental study evaluated 88 freshly extracted maxillary premolars. Single boxes were prepared in the mesial and distal surfaces of the teeth, and amalgam was condensed in the cervical 2 mm of the prepared cavities. The teeth were then randomly divided into 4 groups (n=22). In group 1, after primary setting of amalgam, bonding agent was applied and the cavity was filled with composite resin. In group 2, composite was applied after primary setting of amalgam without the bonding agent. Groups 3 and 4 were restored as groups 1 and 2, respectively with the difference that composite veneer was performed 24 hours after primary setting of amalgam. The teeth were thermocycled, and microleakage was quantified at the amalgam-composite interface using the dye penetration technique. Data were analyzed using the Kruskal-Wallis and Mann Whitney tests. Results: The frequency of microleakage score 0 (no dye penetration) was the highest in groups 1 and 2, followed by groups 3 and 4. No significant difference was noted among the four groups in microleakage scores (P>0.05). Conclusion: Microleakage occurred in all groups at the amalgam-composite interface and use/no use of bonding agent and amalgam setting condition had no significant effect on the occurrence of microleakage.