Microtensile bond strength between adhesive cements and root canal dentin

Abstract

Objectives: The hypotheses tested were that the bond strength of adhesive cements to root canal dentin (1) would be reduced as a function of configuration factor, polymerization process and type of luting material and (2) would be lowered near the apex of the tooth.

Methods: Human canines and premolars were prepared for post cementation using Single Bond/Rely X ARC, ED Primer/Panavia F, C and B Metabond, and Fuji Plus. The specimens were divided into two groups. For intact roots, the posts were luted using standard clinical procedures. For flat roots, the posts were applied directly into flat ground canals. All roots were sectioned into 0.6 mm thick slices, trimmed mesio-distally and stressed to failure at 1 mm/min. The muTBS of each slab was calculated as the force at failure divided by the bonded cross-sectional surface area. The results were compared using a one-way ANOVA and Tukey multiple comparison intervals (alpha=0.05). Least squares linear regression analysis was used to assess the effect of dentin location on bond strength.

Results: All cements showed significantly (p</=0.05) lower bond strengths in intact vs. flat roots. The muTBS of posts to intact roots were not significantly different for Single Bond/Rely X ARC and Panavia F, but both were significantly lower (p</=0.05) than the bonds produced by C and B Metabond and Fuji Plus cements. For Single Bond/Rely X ARC and Fuji Plus a significant decrease in bond strength was observed in dentin closer to the apex of the root.

Significance: Stresses from polymerization shrinkage and problems with adequate access to the root canal complicate the formation of high-strength bonds when cementing endodontic posts with resin cements.