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The Effect of Smear Layer Removal on Endodontic Outcomes

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[Technical Report, Master's Thesis]

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Introduction A layer of organic and inorganic debris referred to as the smear layer is produced during mechanical instrumentation of the root canal system. The combination of ethylene-diamine-tetraacetic-acid EDTA and sodium hypochlorite NaOCl has been shown to effectively remove the smear layer. To date, no prospective controlled in vivo studies have been published examining the effect of smear layer removal on endodontic outcomes in permanent teeth. Objective This randomized, prospective, double-blinded clinical trial compared the endodontic outcomes of teeth where the smear layer was either removed or left intact. A secondary analysis assessed the influence of covariate factors on healing. Methods Subjects meeting study inclusion criteria were randomly assigned to one of two irrigation groups. Root canals were instrumented in a standardized manner followed by a final irrigation of either 1ml of 17 EDTA or 1ml of 0.9 sterile saline. Clinical and radiographic evaluations were completed no earlier than 12- months posttreatment to assess outcomes. A modified periapical index PAI score 1-5 was used for radiographic analysis. Data were analyzed using Fishers exact test a 0.05. Results For this interim analysis of 243 subjects, no significant difference in outcome was found between groups p 0.57. Pre-operative necrosis p 0.01 and a pre-operative apical lesion p 0.0001 were the only covariates found to affect healing rates. Conclusions Within the limitations of this in-vivo clinical study, removal of the smear layer did not affect endodontic outcomes.

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  • Medicine and Medical Research

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[A, Approved For Public Release]