Objective To compare the bonding properties of three kinds of cements by observing the bonding interfaces of cements and root canal dentin. Methods 15 extracted mandibular premolars were divided into 3 groups, and were cemented by Rely X luting, Panavia F and Paracore 5 mL, respectively. Each tooth was sectioned into two parts and the dentin -cement interfaces at the coronal, middle and apical parts of the fiber post were oberved by scanning electron microscope（SEM）. The length of hybrid layer was also recorded. Results Hybrid layer was not clearly found in group one, which could be seen on the dentin-cement interfaces of group two and three. Resin tags and lateral adhesives were also observed in group three. From the apical to the coronal part, microgaps seemed gradually smaller in group one, while the hybrid layer became thicker in both group two and three. Conclusion The totaletch resin cement bounds tightly with dentin, and owns a more superior bonding property than self-etch resin cement and resin modified glass ionomer cement.
