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The Effect of Smear Layer Removal on Endodontic Outcomes

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Technical Report

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Uniformed Services University of the Health Sciences Bethesda United States

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Introduction The biomechanical process of cleaning and shaping the root canal system creates a layer of organic and inorganic debris called the smear layer. This layer is effectively removed using a combination of ethylene-diamine-tetraacetic-acid EDTA and sodium hypochlorite NaOCl. Currently, there are limited clinical outcome studies available to justify the decision to remove or retain the smear layer prior to obturation. Because of this, the practice of smear layer removal is debatable. This prospective, randomized, double-blinded clinical trial compared the endodontic outcomes of teeth in which the smear layer was purposely removed against teeth in which the smear layer remained. Furthermore, the influence of covariant factors on endodontic outcomes was analyzed. Materials and Methods After initial evaluation, all subjects were randomly assigned to either one of the two irrigation protocols. A standardized treatment protocol was followed with the exception of the final irrigation regimen. Group A received 1mlcanal of 17 EDTA while Group B received 1mlcanal of 0.9 saline , each followed by 3mlcanal of 6 NaOCl as the final irrigant. Standardized radiographic and clinical evaluations were conducted no less than 12 months after treatment to determine outcomes. A power analysis determined 440 subjects will be needed for analysis. Data were analyzed using Fishers Exact test 0.05. Results An interim analysis of 147 subjects revealed no significant differences between irrigation protocol groups p0.183. Additionally, the only covariate to significantly affect healed rates was the presence of a pre-operative apical lesion p0.003. Conclusion Under the conditions of this in-vivo clinical study, smear layer removal did not affect endodontic outcomes.

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  • Anatomy and Physiology

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