Methods: 20 recently extracted central incisor teeth free of cracks, visible caries and restoration were prepared for direct laminate veneers. The gingival margin of the preparation was on dentin and the incisal margin of the preparation was on enamel for each teeth. Teeth were randomly divided into two groups. Group 1, restored with microfilled composite (3M Filtek, A110) and Group 2, restored with nanohybrid composite (Voco,Grandio). All teeth were immersed in 0,2 % methylen blue solution for 4 hours after termocycling between 5 C and 55 C for 100 times. Teeth were longitudinaly sectioned and microleakage was observed with a stereomicroscope X50 magnification. Penetration degree was analysed with Mann-Whitney U and Wilcoxon W tests.
Results: No statistically significant differences were found on enamel surface for both groups. Nanohybrid composite showed statistically lower degrees of microleakage than microfilled composite on dentin surface.
Conclusion: Both microfilled and nanohybrid composites can be used safely when the preperation margins are on enamel surface. On dentine surface microfilled composite causes more mikroleakage than nanohybrid composite.