Various conditioning methods for root canals influencing the tensile strength of titanium posts

Conditioning the root canal is frequently advised to achieve high post-retention when resin composite luting cements are used. However, manufacturers' instructions for this purpose differ widely from one another. The aim of this study was to compare the tensile bond strengths of passive, tapered, titanium root posts that were luted with four different resin composite cements (Compolute Aplicap, Flexi-Flow cem, Panavia 21 EX, Twinlook) in the root canals at three conditions, namely (i) no conditioning, (ii) etching with 37% phosphoric acid, and (iii) etching + bonding agent application. Panavia 21 EX was further tested after using the primer for the post-surface according to the manufacturer's recommendations. The posts luted with zinc phosphate cement (Tenet) acted as the control group. Following endodontic preparation of 140 intact anterior teeth with hand instruments, the post-spaces were prepared using the opening drills of the corresponding size of the posts. The samples were first stored in water at 37 degrees C for 24 h and then thermocycled (5000 cycles, 5-55 degrees C, 30 s). The tensile strength values were measured with the universal testing machine at a crosshead speed of 0.5 mm min(-1). The data were analysed statistically using anova and corrected with Scheffé test due to the significance levels (P < 0.05). The tensile bond strengths of the titanium posts after luting with various cements and thermocycling were affected by the conditioning systems used for the root canals. Tensile bond strengths were the highest with Flexi-Flow (475 +/- 78 N) followed in descending order by Panavia 21 EX (442 +/- 97 N), Twinlook (430 +/- 78 N) and Compolute Aplicap (352 +/- 76 N) after conditioning the root canal. The use of primer on the post improved the tensile bond strength compared with the non-conditioned group for the Panavia 21 EX group (375 +/- 77 N) (P < 0.001). Tensile bond strengths obtained after luting the posts with zinc phosphate cement (414 +/- 102 N) were not significantly different (P < 0.05) than those of resin composite cements. Although the importance of conditioning the root canal was evident for Panavia 21 EX, it was not the case for the other luting cements tested.