Anatomical conditions in the systém of root canals represent a significant factor, which can influence the success of endodontic treatment. The structure and anatomy of endodontium is very complex and differs significantly in individual teeth. The failure to respect anatomical deviations is often a cause of failure and may results in extraction of the treated tooth. The authors present three cases, where the difficulties during endodontic treatment were caused by the failure to find a root canal.

        Key words: endodontic treatment - root canal - endodontium anatomy