Evaluation of Microleakage of Bulk-fill Composites by Gas Permeability Method

Objectives: To evaluate the microleakage and marginal adaptation of two bulk-fill composites (Filtek™ and SonicFill™) by gas permeability method.

Methods: Forty human extracted first premolars were randomly divided in two experimental groups (n=16), and two control groups; negative controls (n=4) with complete cyanocrylate coronal-apical sealing, and positive controls (n=4) with coronal-apical patent communication. The teeth length was standardized at 10mm and stored in saline solution for 15 days. After endodontic access was performed, the root canals were cleaned with 5,25% NaOCl and 17% EDTA. A dry cotton pellet was placed at a 4mm depth, and after adhesive protocols the bulk-fill composites were passively placed following the manufacturer indications. All teeth were store with saline solution at 37°C for 20 days.
Gas permeability was evaluated using the Automatic Microleakage Evaluator (EMA). Each sample was stabilized and sealed in metallic rings and placed within the two sealed chambers, connected to piezoelectric pressure sensors. After nitrogen gas injection (20psi) in chamber 1, the pressure differences were recorded for 5 minutes (16 lectures/second). The gas permeability was determined as area under the curve for each sample. The data normality was assessed by Shapiro-Wilk test, and the difference between groups was determined by Wilcoxon Sum Rank test with 95% of confidence. Representative samples were prepared for SEM analysis to evaluate the marginal adaptation.
Results: Mean values between groups were statistically different (p=0.04). Mean (sd) gas permeability values for Filtek™ and SonicFill™ were 685.7 (34.78) and 668.1 (2.62) units respectively. All samples showed acceptable marginal adaptation under SEM observations, however, Filtek™ group showed the presence of peripheral voids in the restoration.
Conclusions: The Filtek™ bulk-fill group showed increased gas microleakage and compromised marginal adaptation when compared to SonicFill™ group.