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 con®guration 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¯at roots, the posts were applied directly into¯at ground canals. All roots were sectioned into 0.6 mm thick slices, trimmed mesio-distally and stressed to failure at 1 mm/min. The mTBS of each slab was calculated as the force at failure divided by the bonded crosssectional surface area. The results were compared using a one-way ANOVA and Tukey multiple comparison intervals a 0:05: Least squares linear regression analysis was used to assess the effect of dentin location on bond strength.Results: All cements showed signi®cantly p # 0:05 lower bond strengths in intact vs.¯at roots. The mTBS of posts to intact roots were not signi®cantly different for Single Bond/Rely X ARC and Panavia F, but both were signi®cantly 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 signi®cant decrease in bond strength was observed in dentin closer to the apex of the root.Signi®cance: 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. q

Relining effects on the push-out shear bond strength of glass fiber posts

“…Compared with the middle and apical thirds, it exhibits higher density of larger-diameter tubules per area 4,5,24 , facilitating the penetration of resin cement 4,5 . With easy visualization and accessibility, procedures such as cleaning, application of adhesive agents and evaporation of materials are efficient 19 .…”

“…In addition, the modulus of elasticity of the posts is similar to that of root dentin 3 , distributing occlusal forces and reducing the risk of severe fractures 4 . Restoration failures usually result from endodontic complications or the cement system used 5,6 , emphasizing that adhesive processes in particular deserve attention.…”

“…Studies on the adhesive capacity of cement systems that have investigated the presence, location and thickness of the hybrid layer in root dentin have suggested that the clinical success of post bonding is associated with frictional rather than micromechanical retention or chemical bond to dentin 5,7,8 .…”

“…Another factor that influences the bond quality is the root canal depth, considering: the dentin morphology; dentinal tubule diameter per area; visualization during the clinical step; and proximity of photo-activating light 4,5 .…”

Relined fiberglass post: an ex vivo study of the resin cement thickness and dentin-resin interface

“…11 The relined fiberglass post allows for a good adaptation in the root canal, enabling the formation of a thin and uniform layer of resin cement and providing a favorable frictional retention. 8 Among the factors that determine the degree of post retention, the selection of the luting agent has been widely studied, and resin cements have shown positive results with respect to their mechanical properties and adhesive capacities 12,13 and are the preferred material to lute the posts. 14 The self-adhesive resin cements RelyX U100 and RelyX U200 have been shown to have greater bond strength values to root dentin compared with other materials.…”