Rationale and efficacy of root canal medicaments and root filling materials with emphasis on treatment outcome

There is overwhelming evidence that endodontic diseases can be characterized as infectious diseases. There is no longer any question that microorganisms are at the center of the etiological causes of pulpal and periradicular pathological processes (1, 2). There are many secondary reasons contributing to tissue breakdown and endodontic failures, such as root perforations, instrument fractures, excess of root canal filling materials and poor technical quality of obturations (3–6). However, none of these seemingly important complications to the treatment will result in failure unless microorganisms infect the damaged area and establish a progressive tissue breakdown. Microbial agents are needed for the expansion of periradicular disease. As there is a microbial cause of progressive periradicular tissue disease, the elimination or reduction of microorganisms in the pulp space and subsequent closure will result in healing.