Effectiveness of different final irrigation solutions on smear layer removal in intraradicular dentin

To compare smear layer removal after root canal final irrigation with 17% Ethylenediaminetetraacetic acid (EDTA), 10% citric acid (CA), Biopure MTAD, and 0.2% chitosan solutions. Fifty extracted maxillary central incisors were decoronated to a root length of 16 mm. They were cleaned and shaped using ProTaper system up to size F4 and 2.5% sodium hypochlorite (NaOCl) irrigation throughout instrumentation. The specimens were divided into 5 equal groups according to the final irrigation solution; group I: 17% EDTA, group II: 10% CA, group III: MTAD, group IV: 0.2% chitosan, group V (control): 2.5% NaOCl. Samples were split longitudinally and examined under scanning electron microscope for smear layer presence at coronal, middle and apical root canal levels. 0.2% chitosan solution has the lowest mean rank of smear layer scores at all tested root sections. The efficacy of MTAD in smear layer removal was better than that of 17% EDTA and 10% CA at the apical level. Coronal sections recorded the lowest mean ranks of smear layer score and the highest was found at the apical section. Final irrigation with 0.2% chitosan solution was more efficient in smear layer removal. 17% EDTA, 10% CA, MTAD and 0.2% chitosan effectively but not completely remove the smear layer especially at the apical root levels.