Currently, clinicians can choose from a wide range of root canal filling materials and techniques, some of which have been evaluated in this thesis.Methacrylate resin-based sealers suffer from polymerization shrinkage stresses. This limitation may partly be overcome by a two-step cementation procedure. This alternative placement technique results in an increase and homogenization of the adhesion of the material to intraradicular dentin. Subsequent research should aim at developing sealers with shorter setting times for clinical implementation and confirm the present proof of concept. It remains to be proven whether an increase in adhesion could be considered as a surrogate for improved sealing ability. With the used methodology, we could not demonstrate any association between the sealing ability and the adhesiveness of an adhesive root canal filling material. Using the low surface tension fluid transport method, the sealing ability of the single-cone technique, after post space preparation, was found to be material dependent, with the epoxy and methacrylate resins providing a better seal than the calcium silicate-based sealer. Roots canals filled with a single-cone technique using gutta percha and a calcium silicate-based root canal sealer were less porous than root canals filled with lateral compaction of gutta percha and the same sealer.Delamination and tearing defects could be observed in root canals filled with hydrogel-coated hygro-expandable cones and a calcium silicate-based sealer. Hydrogels are smart materials that may currently be inadequate for endodontic use with calcium silicate sealers.The use of simulated body fluids for testing the bioactive potential of calcium silicate-based fillings leads to the deposition calcium phosphate. This phenomenon may however be simply reflecting a thermodynamic process rather than expressing bioactivity potential. An explanted specimen revealed the formation of calcium carbonate (calcite) and the absence of calcium phosphate on its surface.