Objective To observe the microscopic characteristic of the dentinal surface and cross section after using dental desensitizer, and evaluate the effect of the dental desensitizer on the shear strength of resin cements. Methods To use the dental desensitizer（Gluma, Single Bond 2, BisBlockTM） individually on the prepared human bicuspid teeth which were extracted for orthopaedics. The microscopic characteristic of the dentinal surface and cross section were observed with scanning electron microscope（SEM）. The adhered posts to the teeth pretreated with desensitizer were bonded with resin cements. The shear strength was measured and data was analyzed by SPSS 13.0 statistics software. Results The orifices of dentinal tubule were mostly occluded in Gluma samples and partly occluded in BisBlockTM samples. Resin layer was observed in Single Bond 2 samples. BisBlockTM group gathered the best shear strength, the shear strength value was （13.04 ±2.76）MPa. Marked statistic difference were found when compared with control group. Conclusion Gluma, Single Bond 2 and BisBlockTM can block the orifices of dentinal tubule. BisBlockTM enhanced the bonding strength of the resin cements.
