Objective To study the effects of two primers on the bond strengths between casting pure titanium and resin cements. Methods Two sizes of specimen were fabricated by casting, which diameter were 4 mm and 5 mm respectively, and then were cut into 3 mm thick titanium discs. The titanium surfaces were polished with silicon carbide sand papers under running water and then treated by sandblasting. The two size of titanium disc were ultrasonic cleaned and treated with Alloy Primer, V-Primer or without primer, and then bonded in pairs with the resin -based cements Super -Bond C&B, Panavia F and Rely X Unicem. The specimens were then stored in distilled water（37 ℃） for 24 h. Bond strengths were determined before and after 5 000 thermocycling. The titanium surface morphous and failure mode of the teat specimen were observed. Results The shear bond strengths of titanium treated by Alloy Primer to Super-Bond C&B were （31.23±4.86）, （34.08±3.36）MPa before and after 5 000 thermocycling, which higher than that of other combinations of primers and resin cements. Conclusion Bond strengths were influenced by primers, resin cements, and their combinations. The highest bond strengths were the combinations of Alloy Primer and Super-Bond C&B.
