Introduction: A randomized controlled double blinded clinical trial to assess the outcome of initial root canal therapy with or without smear layer removal.
Methods: Patients requiring initial non-surgical root canal treatment were eligible for enrollment. Consented subjects were randomly assigned into one of two groups differentiated by final irrigation protocol. All canals were prepared using a standardized instrumentation protocol and received a blinded irrigation of either 1 ml/canal of 17% EDTA –to remove the smear layer- or 1 ml/canal of 0.9% saline. A standardized obturation was completed with zinc oxide eugenol sealer (Roth) using continuous wave compaction. A final radiograph was taken for use in the outcome assessment. Subjects were recalled after at least 12 months for clinical and radiographic evaluation. Radiographs were scored using a modified periapical index (PAI) score of 1-5 by three board certified endodontists. A Fisher’s Exact test and Cohen’s Kappa (p < 0.05) were used to analyze the results.
Results: A recall rate of 83% was achieved for a total of 283 subjects included in the analysis. The mean follow up period was 13 months. The overall healed rate was 66.8%-70% for the saline group and 64% for the EDTA group - with no significant differences between the two study groups.
Conclusions: Outcome of initial nonsurgical endodontic treatment is not dependent on the removal of the smear layer.
