Failure of Root Canal Treatment

Root canal retreatment is often the preferred method of treating a tooth in which root canal treatment has failed. Part one of this two-part article discusses reasons for failure of root canal treatment, case assessment and treatment planning. Part two describes some of the practical techniques that are available to the practitioner and the rationale for root canal retreatment. Dent Update 2004; 31: 34–39 Clinical Relevance: Root canal retreatment may prevent unnecessary extraction in a root-filled tooth with persisting apical periodontitis. E N D O D O N T I C S he success rates for root canal treatment have been widely quoted and there is marked variation in the ability of operators to achieve successful results. In many countries, studies using data collected from general practice have shown relatively low success rates for root canal treatment. A recent study in England and Wales showed that 97% of molar root canal treatment and 84% of canine and incisor root canal treatment had technical difficulties; in a Scottish study, over 58% of root-filled teeth showed signs of periapical radiolucency. Similar radiographic results have been found in studies from the USA, Holland and Sweden. At the other end of the spectrum, studies using samples derived from teaching hospitals have shown much higher success rates 70–95%. So why is there such a difference, and why do root canal treatments fail? FAILURE OF ROOT CANAL TREATMENT Biological failings of root canal treatment include: l No rubber dam; l Incorrect irrigants; l Inability to prepare the canal to length; l Missed canals; l Poor obturation. Other causes of failure include: l Root fracture; l Poor coronal restoration; l Resistant bacteria; l Economic constraints. Biological Failings