Procedures for retreatment of failed root canal therapy

elderly-man_dental-exam-2In root canal therapy, the infected pulp of a tooth is removed, and the root cavity is disinfected and filled with a sealing material. However, if micro-organisms that caused the infection are not completely removed, after some time they may cause a disease at the tip of the root, called a periapical lesion. Treatment for this requires a second intervention, which can be performed in the same way as the first treatment, from the crown into the root canal, to remove the existing filler and clean and disinfect as well as possible before sealing again. Alternatively, should this procedure fail, or if it is not feasible, a surgical intervention can be used.

What was the research?

A systematic review to find out the best way to retreat patients for whom root canal therapy has failed. We wanted to know whether surgical or non-surgical retreatment was better, and if using specific materials, devices or procedures in surgery might improve healing of the lesion or reduce patient discomfort after surgery. This review updates one published in 2008.

Who conducted the research?

The research was conducted by a team led by Massimo Del Fabbro, from Università degli Studi di Milano, Italy, on behalf of Cochrane Oral Health.Stefano Corbella, Patrick Sequeira-Byron, Igor Tsesis, Eyal Rosen, Alessandra Lolato and Silvio Taschieri were also on the team.

What evidence was included in the review?

We conducted a wide search of medical and dental literature up to 10 February 2016. We identified 20 randomised controlled trials that randomised participants to groups receiving different forms of retreatment of periapical lesions. These studies evaluated nine different comparisons: surgical versus non-surgical treatment (two studies, one monitoring participants for up to 10 years); two diagnostic radiographic techniques (one study); the occurrence of postoperative infection with or without antibiotics (one study); use of different devices for enhancing the surgeon’s view during the most critical steps of the surgical procedure (one study); the aesthetic appearance of the gum next to the treated tooth and pain after operation when two different types of gingival incision were used (two studies); use of minimally invasive ultrasonic devices or traditional rotating burs to manage the tip of the root (one study); use of different materials for filling the root-end (seven studies); filling of the periapical lesion with a grafting material (four studies); and exposure of the surgical site to a low energy level laser to reduce pain (one study).

What did the evidence say?

There is no evidence that a surgical approach leads to better results compared with non-surgical retreatment at one year (or at four or 10 years) after intervention. However, people treated surgically reported more pain and swelling during the first week after treatment.

Different surgical techniques were evaluated. Healing at one-year follow-up seemed to be improved by use of ultrasonic devices, instead of the traditional bur, for root-end preparation. There was some evidence of better healing at one-year follow-up when root-ends were filled with mineral trioxide aggregate compared with their being treated by smoothing of orthograde gutta percha root filling.

Use of a graft composed of a gel enriched with the patient’s own platelets applied to the defect during the surgical procedure significantly reduced postoperative pain. Exposure to a low energy level laser did not apparently reduce pain at the surgical site.

A small gingival incision may preserve the gum between two adjacent teeth, improving the aesthetic appearance and causing less pain after surgery.

There was no evidence that use of antibiotics reduces the occurrence of postoperative infection (although when the procedure is done well, infection is an extremely rare event).

Different ways of enhancing the surgeon’s view did not lead to different results at least one year after operation, and results of retreatment were independent of the radiographic technique used to make the diagnosis.

How good was the evidence?

We judged the quality of the evidence to be poor; therefore we cannot rely on the findings. Only one study was at low risk of bias;we judged the majority to be at high risk of bias.

What are the implications for dentists and the general public?

Overall, none of the review findings can be assumed to be conclusive, as the quality of the evidence was low to very low. Information is still insufficient to inform clinicians whether root canal retreatment or root-end resection should be used, and which procedures for root-end resection should be followed to achieve the best results for patients.

What should researchers look at in the future?

All questions addressed in this review need further investigation if we are to understand whether a surgical or a non-surgical approach should be used, and which surgical procedures may provide the best and most predictable results, in terms of healing of periapical lesions and quality of life of the patient in the postoperative period. Future studies should use standardised techniques and success criteria, precisely defined outcomes and specific features of the periapical lesion. Investigators should use the participant – not the tooth – as the analysis unit, if possible, and should follow the CONSORT recommendations for reporting.


Del Fabbro M, Corbella S, Sequeira-Byron P, Tsesis I, Rosen E, Lolato A, Taschieri S. Endodontic procedures for retreatment of periapical lesions. Cochrane Database of Systematic Reviews 2016, Issue 10. Art. No.: CD005511. DOI: 10.1002/14651858.CD005511.pub3.

This post is an extended version of the review’s plain language summary, compiled by Anne Littlewood at the Cochrane Oral Health Editorial Base.