A new strategy in root canal therapy: there is a lot going on in endodontic disinfection

Apical periodontitis (AP) is the inflammatory response in the surrounding tissues at the root tip of a tooth to a microbial infection of the root canal system inside the tooth. AP can only resolve after thorough root canal disinfection. However at present, state-of-the-art root canal treatment does not always result in sufficient decontamination. This thesis describes the development of a new strategy which even disinfects the complex structures of the root canal system. The strategy is based on a multiple-hurdle principle and has been tested in various in-vitro models with varying conditions. An application, the modified salt solution, has been developed.
In the second part of the thesis, aspects of current root canal disinfection have been investigated. At present, sodium hypochlorite (NaOCl) is the most used root canal disinfectant. It is an unstable molecule and therefore the quality of NaOCl solutions in dental practices has been evaluated. It appeared that frequently the concentration of NaOCl was lower than expected.
Sometimes, root canal disinfection takes place in two treatment sessions. Then, calcium hydroxide (CH) is used to temporarily dress the root canals between the sessions, with the aim to further reduce the microbial load. This thesis shows that CH cannot eliminate biofilm bacteria and that side-effects after CH application occur. In the biofilms, CH causes a precipitate. Also, the susceptibility of bacterial species to disinfection may alter. Application of CH then results in a shift in biofilm composition in favour of the most resilient species.