Microleakage and Micrographic Evaluation of Composite Restorations with Various Bases over ZOE Layer in Pulpotomized Primary Molars

Objective: Zinc oxide eugenol (ZOE) under composite restorations should be covered with a suitable material in order to prevent the harmful effect of ZOE on the composite. The aim of this in vitro study was to evaluate microleakage of composite restorations in pulpotomized primary molars with different bases for covering the ZOE layer and to assess the distance between different layers. Materials and Methods: Proximo-occlusal cavities were prepared in 78 extracted second primary molars. Carious lesions were removed and pulpotomy was carried out. Zinc oxide eugenol paste was placed in 2-mm thickness. The teeth were randomly divided in 6 groups and restored as follows: 1. Light-cured composite; 2. Resin-modified glass-ionomer and composite resin; 3. Glass-ionomer and composite resin; 4. Light-cured calcium hydroxide and composite resin; 5. Calcium hydroxide and composite resin; 6. Amalgam and composite resin. The restored specimens were thermocycled for 500 cycles (5°C/55°C) and microleakage was assessed by dye penetration technique. Three specimens from each group were processed for scanning electron microscope evaluation to determine the distance between the layers. The results were analyzed by Kruskal-Wallis and Dunn tests. Results: Microleakage assessment revealed significant differences between the groups (P=0.04), with the amalgam group exhibiting the lowest microleakage values. In SEM micrographs no significant differences were observed in the distance between ZOE base layers (P=0.94) and base-composite layers (P=0.47); however, the amalgam group had the lowest distances. Conclusion: The use of amalgam over zinc oxide eugenol layer in pulpotomized primary molars decreases microleakage.