In vitro microleakage comparison of flowable nanocomposites and conventional materials used in the treatment of pit and fissure sealant

Pit and fissure sealant is recognized as an effective preventive approach in pediatric dentistry. The most commonly used sealant material is resin composite. Adding nanoparticles to resin composites could result in production of flowable material with both higher mechanical properties and better flow characteristics than previous sealants. This study aimed to compare the microleakage of a flowable nanocomposite and conventional materials used in the treatment of pit and fissure sealants. A total of 185 extracted mandibular third molar teeth were selected and randomly divided into 5 groups of 36 according to material used as pit and fissure sealant, and the microleakage of flowable nanocomposite, flowable composite, filled sealants, nano-filled sealants and unfilled sealants were compared. Five teeth were reserved for examination under the scanning electron microscope. The samples were thermocycled (5 - 55 degrees C, 1-minute dwell time) at 1000 cycles and immersed in 0.2% fuchsine solution for 24h. teeth were sectioned buccolingually . Microleakage was assessed by means of dye penetration and scanning electron microscope. Data were analyzes using Kruskal-Wallis non- parametric test (p<0.05), Mann-Whitney test p <0.005, and SPSS ver.16.  The nanofilled flowable composite and unfilled fissure sealant showed the lowest and highest rates of microleakage, respectively. No statistically significant difference was found between two flowable composite (P=0.317). Filled resin-based sealant had significantly lower microleakage than unfilled resin-based sealant (P<0.001).   Concerning the microleakage data, use of a flowable nanocomposite is more effective in sealing mechanically prepared occlusal fissures in comparison to the unfilled sealant.