Micropush-out bond strengths of gutta-percha versus thermoplastic synthetic polymer-based systems - an ex vivo study

To compare the interfacial strength and failure mode of root fillings consisting of different technique-material combinations.

Human mandibular premolars (n = 144) instrumented to apical size 40 and .06 taper were divided into 12 experimental groups. The root canals were filled with either gutta-percha (groups 1-6) or Resilon (groups 7-12) core materials combined with AH Plus (groups 1, 4, 7, 10), Ketac-Endo (groups 2, 5, 8, 11) or Epiphany (groups 3, 6, 9, 12) using cold lateral compaction (groups 1-3, groups 7-9) or System B with Obtura II (groups 4-6, groups 10-12). Three serial 1.00 +/- 0.05-mm-thick root slices were prepared and push-out tests on the filling material were performed. Interactions amongst the compaction techniques, core materials and sealers were analysed using a three-way analysis of variance (anova) (P < 0.05). One-way anova and Duncan's Multiple Range tests were used to compare the bond strengths of the 12 groups. Fracture modes of all root slices were evaluated stereomicroscopically at x40 magnification.

All the parameters except compaction techniques had significant interactions (P < 0.05). A significant difference was found amongst the groups (P < 0.05). Gutta-percha/Ketac-Endo/cold lateral compaction and gutta-percha/AH Plus/cold lateral compaction groups had the highest micropush-out bond strength values (P < 0.05). The number of overall cohesive failures was significantly more than that of adhesive failures (P < 0.05).

The push-out bond strengths of Resilon/Epiphany combinations were lower than those of gutta-percha/conventional root canal sealer combinations. Core materials and sealers may affect the push-out bond strengths of root canal filling materials.