Objective To evaluate the coronal microleakage of teeth restored with fiber posts and composite cores with four different resin bonding systems. Methods Sixty extracted human maxillary single-rooted teeth were endodontically treated and randomly divided into four groups. Post spaces were prepared in the root canals. Four different resin bonding systems（RelyX Unicem, Dulink, DC core Automix, Luxacore）were used respectively to bond fiber posts and reconstruct cores. The specimens were immersed in India ink for one week. Subsequently all teeth were demineralized, dehydrated and rendered transparent. Then microleakage was observed with stereomicroscope. Results The microleakage degrees among four resin bonding systems were significantly different（P=0.007）, and group C showed the least microleakage compared with the other three. Conclusion Self-etching resin bonding systems have a super margin sealing ability.
