Interactions between root canal irrigants, sealers and dentin

The objective of this thesis was to determine the interactions between root filling materials and root dentin and to investigate if root canal irrigating solutions had an impact on these interactions. The following outcomes were assessed in the studies encompassed in this thesis: (i) dislocation resistance of an epoxy resin based root canal sealer and tricalcium silicate based root canal sealers, (ii) the influence of irrigation protocols on the sealing ability and chemical interactions with dentin of an epoxy resin based sealer, (iii) retreatability of mineral trioxide aggregate based sealers, (iv) characterization of a mineral trioxide aggregate based sealer following exposure to irrigation regimens. The results showed that irrigation protocols differentially influenced the sealer materials. The use of continuous chelation (sodium hypochlorite + etidronic acid) enhanced the bond strength of epoxy resin as well as mineral trioxide aggregate based sealers. This irrigation regimen also positively influenced the hydration characteristics of the tricalcium silicate materials. The bond strength of tricalcium silicate sealers improved with time. The epoxy resin sealer AH Plus chemically bonds to root dentin and irrigation protocols employing a final rinse of a proteolytic irrigant reduced the bond strength. Use of a final rinse of EDTA after continuous chelation significantly improved the bond strength of the epoxy resin sealer. Retreatability of mineral trioxide aggregate based sealers depends on the composition of the material with sealers containing a resin component being easily removable than compositions with without a resin.