Efficacy of Four Treatment Procedures in Removal of Smear Layer during Root Canal Treatment

Purpose: To evaluate efficacy of four treatments in smear layer removal on cut dentinal surface and on root canals. Methods: The four treatments were—1) Glide® Dentsply + 6% NaClO + 17% EDTA; 2) Glide® Dentsply + 6% NaClO + anolyte (Anolyte of Electrochemically Activated Water [ECA]); 3) Glide® Dentsply + catholyte [ECA] + anolyte [ECA]; 4) Chlorine Dioxide gel (20-30 ppm ClO2, Frontier Pharmaceuticals) + 6% NaClO. To study smear layer removal, six cut dentinal surfaces per treatment and eight root canals were used in this study. Glide® was applied and rubbed for five minutes followed by 15-minute contact with either NaClO or catholyte and 10 minutes with either EDTA or anolyte. One sample per group was studied using SEM while the other samples were bonded with Delton® Caulk Dentsply flowable composite, and shear bond strength was calculated as a surrogate measure for adaptation. To study smear layer removal in canals eight canals per treatment group were used with a preparation time of 25 minutes, and canal surfaces were studied using SEM. Results: Group 1 showed the highest shear bond strength of 34.9 (SD 6.0) MPa while group 2 showed the lowest 22.2 (SD 4.7) MPa (p > 0.05). SEM of the canals showed group 1 with clean dentinal tubules and the others with varying degrees of smear layer removal. Conclusion: In this preliminary study, the 6% bleach and 17% EDTA were found to be superior to the other treatment groups, but some of the other treatments also showed promise. Further evaluation needs to be done with respect to alteration in procedures and larger samples for definitive results. Materials were provided in part from Dentsply Professional, Tulsa Dental, and Frontier Pharmaceuticals, USA.