Effects of Different Root Canal Obturation Techniques on the Bond Strength of Fiber Post to Intraradicular Dentine.

OBJECTIVE To evaluate the bond strength of fiber posts to intraradicular dentine pretreated with two root canal obturation techniques and three postspace irrigation solutions. METHODS A total of 96 human premolars were collected and treated with complete or partial root canal obturation techniques. The roots were further divided into three subgroups (n = 16) based on postspace irrigation solutions: 2.5% NaOCl, 37% phosphoric acid etching, and distilled water. The fiber posts were bonded with self-adhesive resin cement, and the roots were sectioned into three slices (cervical, middle, and apical regions) after 5,000 thermocycles. The push-out bond strengths were determined and subjected to analysis of variance (α = 0.05). A stereomicroscope was used to observe the failure modes of the specimens. RESULTS The irrigation solution, root canal obturation technique, and root region had significant effects on bond strength (P < 0.001). The completely obturated root canals showed significantly lower bond strength than the partially obturated root canals. The 2.5% NaOCl treatment produced the highest bond strength among the three irrigation solutions. Among the root regions, the cervical part showed significantly greater bond strength than the middle and apical parts. The most common failure mode was mixed failure. CONCLUSION The partial root canal obturation technique provided better bond strength of the fiber post to intraradicular dentine. Irrigation with 2.5% NaOCl solution and phosphoric acid etching before cementation improved the push-out bond strength of the fiber posts to intraradicular dentine.