Consequences of and strategies to deal with residual post-treatment root canal infection

Abstract Wu M-K, Dummer PMH, Wesselink PR. Consequences ofand strategies to deal with residual post-treatment root canalinfection. International Endodontic Journal, 39, 343–356, 2006. Bacterial sampling of prepared root canals is used todetermine the presence and character of the remainingmicrobiota. However, it is likely that current samplingtechniques only identify organisms in the main bran-ches of the root canal system whereas it is unlikely thatthey can sample areas beyond the apical end-point ofpreparation and filling, or in lateral canals, canalextensions, apical ramifications, isthmuses and withindentinal tubules. Thus, it may be impossible by currenttechniques to identify residual post-treatment rootcanal infection.In histologic observations of root apices,bacteria have been found in inaccessible inter-canalisthmuses and accessory canals often in the form ofbiofilms. There is no in vivo evidence to support theassumption that these bacteria can be entombedeffectively in the canal system by the root filling andthus be rendered harmless. As a consequence of thisresidual root infection, post-treatment apical periodon-titis, which may be radiographically undetectable, maypersist or develop as a defence mechanism to preventthe systemic spread of bacteria and/or their byproductsto other sites of the body.Histologic observation of rootapices with surrounding bone removed from eitherpatients or human cadavers has demonstrated thatpost-treatment apical periodontitis is associated with50–90% of root filled human teeth. Thus, if theobjective of root canal treatment is to eliminate apicalperiodontitis at a histological level, current treatmentprocedures are inadequate. It is essential that ourknowledge of the local and systemic consequences ofboth residual post-treatment root infection and post-treatment apical periodontitis be improved. The con-tinued development of treatments that can effectivelyeliminate root infection is therefore a priority in clinicalendodontic research.Post-treatment disease followingroot canal treatment is most often associated with poorquality procedures that do not remove intra-canalinfection; this scenario can be corrected via a nonsur-gical approach. However, infection remaining in theinaccessible apical areas, extraradicular infection inclu-ding apically extruded dentine debris with bacteriapresent in dentinal tubules, true radicular cysts, andforeign body reactions require a surgical intervention.Keywords: apical health, apical periodontitis,endodontics, post-treatment disease, root canal infection.