Root canal obturation still is a relevant research topic and patients spend substantial amounts of financial resources for this step of endodontic treatment. Three experiments were conducted challenging the necessity of root canal obturation.Applying micro computed tomography, the volume of dentin tubules that cannot be instrumented during root canal therapy was determined. Using a simple biofilm model of human tooth segments, the effect of root canal obturation on the persistency of bacteria was evaluated and freshly extracted root canal treated teeth were examined for bacteria remaining in dentin.The volume of dentinal canals was found to be at least three times greater than the volume of the root canal itself. Bacterial growth was observed both in specimens with and without root canal obturation implying that the treatment rendered was ineffective in removing bacterial biofilm and the obturation material was incapable of hindering bacterial regrowth.Despite showing adequate root canal obturation radiographically, persistent bacteria could be identified in all teeth extracted. While perfect disinfection of root canals is mandatory, root canal obturation seems questionable as current materials have no antibacterial activity, do not stabilize the tooth, and cannot seal the canal system if a coronal restoration is missing.