Smear layer and debris removal from dentinal tubules using different irrigation protocols: scanning electron microscopic evaluation, an in vitro study

Background This study investigated the ability of different irrigation protocols to keep dentinal tubules (DT) open and avoid their blockage by the smear layer (SL) during the cleaning and shaping procedure (CSP). Methods Twenty-five extracted teeth were divided into five groups ( n = 5): group 1, NaOCl was kept in the canal during instrumentation and then washed out with distilled water, and the canal was irrigated with NaOCl with EndoVac in between files; group 2, the same procedure as group 1, but NaOCl was replaced by EDTA; group 3, EDTA was kept in the canal during instrumentation and then washed out with distilled water, and the canal was irrigated with NaOCl with EndoVac in between files; group 4, the same as group 3, but NaOCl and EDTA were alternated; and group 5 (control), the procedure was the same with group 1, but NaOCl was replaced by distilled water. A scanning electron microscope was used to evaluate the cleanliness of DT at three different levels of the canals. Results Groups 3 and 4 showed better ability to keep DT open during CSP than the other groups. Group 4 only showed statistically significant better results than group 3 at middle third ( P