Non-microbial factors have also been suggested as a potential cause of post-treatment disease, 9 but evidence is relatively weak as it comes from a few case reports. This can be a persistent or secondary intraradicular infection, but in some cases it may be an extraradicular infection. The cause of post-treatment disease is essentially bacterial infection. Post-treatment disease has been reported to occur in 5-15% of teeth with pre-operative apical periodontitis even when treatment has followed proper standards. Nevertheless, post-treatment apical periodontitis can also be observed in some teeth that were apparently well treated. 2, 3, 4, 5 In these cases it is not difficult to realise the cause of disease: persistent or secondary root canal infection resulting from inadequate treatment.

Post-treatment apical periodontitis is usually observed after endodontic treatments that have not followed acceptable standards for prevention and control of the root canal infection. 1 These are the same diseases as the primary apical periodontitis associated with untreated canals the difference is the root canal conditions. This is often referred to as post-treatment apical periodontitis, which can be categorised as emergent (if developed after treatment), persistent (if persisted despite treatment), or recurrent (if developed after having healed). The occurrence of signs and/or symptoms of disease in association with root canal-treated teeth means that apical periodontitis (disease) is present.

The main objectives of endodontic treatment are to prevent or treat apical periodontitis so that the tooth can be retained in the oral cavity in healthy conditions.

Endodontic teeth