Effect of cleaning method, luting agent and preparation procedure on the retention of fibre posts

Abstract

Aim: To investigate the effects of various cleaning methods, luting agents and preparation procedures on fibre post retention.

Methodology: In total, 156 human canines were allocated to twelve groups. Teeth were decoronated, instrumented and root filled using warm vertical gutta-percha compaction. Post space preparation was performed in 78 roots using the dedicated preparation drills of the DT Light Post SL system [group post drill (PD)]. Gutta-percha was removed from the other 78 roots using a round bur (RB) (group RB). Within each of these two groups, 26 root canals were rinsed with 1% NaOCl (control), 26 were cleaned using rotating brushes and pumice powder, and 26 were sandblasted with Al(2) O (3) (50 μm) using an intraoral device. Cleanliness of each root canal was investigated using an operating microscope (n = 24) and scanning electron microscope (n = 2). Fibre posts were inserted using self-adhesive resin cement (SmartCem2) or core build-up material (CoreX Flow/XP Bond). Pull-out force was measured using a universal testing machine. Statistical analyses were performed using three-way anova and Tukey's HSD post hoc tests.

Results: Root canal cleanliness was not affected by the cleaning method (P = 0.618, chi-squared test). Pull-out force for fibre posts was significantly affected by the cleaning method (P = 0.008), the luting agent (P < 0.0005) and the preparation procedure (P < 0.0005, three-way anova). RB group demonstrated significantly higher pull-out forces [399 (88) N] compared with PD group [287 (105) N]. Posts that were inserted using CoreX Flow/XP Bond exhibited significantly higher pull-out forces [370 (62) N] compared with posts inserted using SmartCem2 [315 (141) N].

Conclusion: The different cleaning methods did not lead to significant differences in root canal cleanliness and did not enhance fibre post retention inside the root canal. However, post space preparation using a RB might be beneficial for improving retention, especially when self-adhesive cements are used. The use of the core build-up material CoreX Flow/XP Bond instead of the self-adhesive resin cement, SmartCem 2, resulted in significantly higher pull-out force.