Effect of cleaning method, luting agent and preparation procedure on the retention of fibre posts.
OBJECTIVE
To investigate the effects of various cleaning methods, luting agents and preparation procedures on fibre post retention.


METHODS
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].


CONCLUSIONS
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.
Department of Operative Dentistry and Periodontology, University School of Dental Medicine, CharitéCentrum 3, Charité - Universitätsmedizin Berlin, Berlin, Germany. kerstin.bitter@charite.de
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Bitter
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Eirich
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Neumann
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Weiger
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Krastl
D001840:Dental Bonding; D003738:Dental Cements; D017268:Dental Prosthesis Retention; D003799:Dental Stress Analysis; D006171:Gutta-Percha; D006801:Humans; D011176:Post and Core Technique; D012389:Root Canal Obturation; D018915:Root Canal Preparation / Q000295:instrumentation* / Q000379:methods*
D003738:Dental Cements; D006171:Gutta-Percha