ABSTRACT
Polymerization shrinkage is one of the most common causes of microleakage in packable composites. Various methods are recommended to reduce polymerization shrinkage and the application of flowable composites is one of these methods. The aim of the current study was to evaluate the effect of flowable composite on the microleakage of packable resin composite in class II cavities. This experimental study was performed at Dental School of Shahid Sadoughi University, Yazd [Iran] in 2006. On 32 recently extracted upper premolar teeth, the mesial and distal class II cavities with the same dimensions were created. The teeth were randomly assigned into two groups: the distal surfaces of the first group were restored with P60 while in the other group restoration was accomplished with Solitaire resin composite. The mesial aspects of the teeth were filled with Filtekflow flowable composite and other composites mentioned above. After thermocycling, the samples were soaked in 2% methylene blue solution followed by sectioning in mesiodistal direction. The degree of microleakage was evaluated by stereomicroscope with 25 X magnification. Data were subjected to the chi-square and Exact tests, statistically. The flowable composite failed to reduce the degree of microleakage in axial wall and gingival floors [p>0.05]. The application of flowable resin composite caused no effect on microleakage of class II packable resin composite restorations