Does Smear Layer Removal Influence Root Canal Therapy Outcome? A Systematic Review.

Objective: The aim of this systematic review was to determine whether the smear layer (SL) removal procedure influences the outcome of root canal treatment.
Study Design: We performed a search on Pubmed, Scopus, ISI Web of Science, Cochrane Library, Lilacs and SIGLE. We included randomized controlled clinical trials (RCT), with clinical and radiographic outcomes, conducted on subjects who had undergone root canal therapy. The protocol differed only in the SL removal or maintenance procedure. We evaluated the papers for risk of bias according to the Cochrane assessment tool.
Results: A total of 1,983 articles were found, after removal of duplicates, 892 remained. We included two studies in this review. One study revealed a low risk of bias and a high success rate for the SL removal group compared to the non SL removal group (P = 0.04), while the other study had a high risk of bias and found no difference between the SL removal and non SL removal groups (P = 1.00).
Conclusion: We concluded that the SL removal for root canal treatment of primary teeth with initial clinical signs and symptoms or pulpal necrotic status, could benefit the outcome, although further RCT should be performed to achieve evidence.