Objectives: Polymerization shrinkage stress in composite restorations may lead to microleakage. Clinical methods such as using low-shrinkage composites and using stress breaking liners under composites have been suggested to overcome this problem.
Materials and Methods:
90 Standardized cylindrical class V cavities of 2x4 mm (depth×width) were prepared on the gingival third of the buccal surface of the sound human premolars teeth. The teeth were randomly divided into 2 groups. In group A1, Excite, Total etch Adhesive system was applied in one layer. In group A2, G Bond Adhesive system applied Every group was then divided into three subgroups of 15 Specimens each, relative to the type of liner material used, R1:grop for Low shrinkage resin composite restoration without liner, R2:group for Low shrinkage resin composite restoration with flowable resin composite liner and R3: group for Low shrinkage resin composite restoration with- (R.M.G.I) liner, Each subgroup was further divided according to storage time into three divisions of 5 Specimens each, S1: 24 hours, S2: three month and S3: six months. The samples were thermocycled and immersed in an aqueous solution of 2 % methylene blue for 24h. The restorations were sectioned in buccolingual direction. Then they were evaluated for microleakage by using a stereomicroscope.
Results:
The groups were not significantly different regarding the microleakage in the Low shrinkage resin composite restoration with flowable resin composite liner yielded the best results.
Conclusion:
The results suggested that The use of low-shrinkage resin composites with liner may offer better comparable clinical results.