摘要：Objective: The aim of this in vitro study was to evaluate and compare the effect of using different base materials on microleakage of class V restorations. Materials and Method : In this study 60 extracted non-cavitated human molar teeth were used. Class V cavities were prepared on the buccal surfaces in 4 mm mesio-distal, 3 mm gingivo-occlusal width and 3 mm depth. The teeth were randomly divided into five groups: Group 1: resin-modified calcium silicate material (TheraCal LC), Group 2: self-adhesive flowable composite resin (Fusio Liquid Dentin), Group 3: flowable composite resin liner (Tetric N Flow), Group 4: resin-modified glass ionomer liner (Ketac N100), Group 5: control group. Materials in the experimental groups were placed in 1 mm thickness as liner. Then, a nanohybrid composite resin (Grandio) was placed and restorations were completed. In the control group, no base material was applied. After finishing and polishing procedures, thermocycling was performed 5000 times between 5-55 °C. Microleakage of restorations was evaluated by using dye penetration method (basic fuchsin). Results were analyzed by Kruskal Wallis with Bonferroni correction and Mann-Whitney U tests. Results: Regarding occlusal microleakage, no statistically significant difference was found between the groups (p=0.267); however significant difference was found between the gingival microleakage scores (p=0.004). Compared to Fusio Liquid Dentin and control groups, significantly less dye penetration was found in Theracal LC, Tetric N-Flow and Ketac N-100 groups (p<0.01). No significant difference was found between the occlusal and gingival sides of the restorations in any of the test group (p>0.01). Conclusion: Within the limitation of this study, the conclusion was that the use of a liner (except Fusio Liquid Dentin) under composite resin in a class V cavity reduced the microleakage of the restoration.
