Micro leakage is critical at the margins of cervical lesions because of the lack of enamel. So the main objective of tooth restoration is the protection of exposed dentin against microbes and their toxins. The interface between restoration and dental hard tissue is an area of clinical concern as insufficient sealing can result in some dental pathology. Context: Micro leakage is a matter of concern because it leads to staining at the margins of restorations, recurrent caries, hypersensitivity and pulp pathology. Aim: The aim and objective of this study is to evaluate and compare the sealing ability and the amount of micro leakage caused by two different intermediate materials that is Flowable composite and Resin modified glass ionomer cement in class V composite restoration in enamel and cementum margins. Methods and Material: Thirty fresh human premolars were randomly divided into 3 groups of 10 teeth each, based on the presence or absence of liner or if present the type of liner. On the lower third of the buccal surface of each tooth , class V cavity were prepared with a high speed air rotor hand piece .The cavities were located on the cemento enamel junction , half in cementum and half in occlusal enamel. Then the teeth of each group were subdivided into thermocycled and not thermocycled subgroups and then the teeth were suspended in methylene blue solution for 12 hrs. The samples were sectioned buccolingually and the depth of dye penetration was measured with a stereomicroscope. Statistical analysis: Statistical test employed for the obtained data in our study was Chi-Square (2) Test Results: The degree of microleakage in the gingival margin was more than in the occlusal margin. There is a significant statistical difference found between the intermediate materials in occlusal margin. Flowable composites showed less leakage than light cure RMGIC and the control group in which no liner was present. Thermocycling had no effect on microleakage in all the three groups at both occlusal and gingival margins. Conclusion: None of the two intermediate materials completely sealed the tooth/restoration interface at occlusal and gingival margin.
Key-words: Microleakage, Class five cavity, Liners, Flowable composite, Light cured RMGIC.