Efficacy of different chelating agents in smear layer removal

Aim The aim of this study was to assess the ability of 17% EDTA, 10% citric acid, 2.25% peracetic acid and 1% phytic acid (IP6) in removing smear layer from root canal system of human teeth using scanning electron microscopic analysis. Materials and methods Forty freshly extracted single canal human mandibular premolars with nearly straight mature fully developed roots were used in this study. Teeth were decoronated perpendicular to their long axises leaving roots ∼ 13 ± 1 mm. Chemomechanical preparation was done using ProTaper instrument in a crown down technique up to F4 master apical file (40/0.06) with irrigation of 2.5% sodium hypochlorite throughout instrumentation. Depending on the used final irrigation solution, the samples were divided randomly into four experimental groups (n = 10). Group I: 17% EDTA. Group II: 10% citric acid. Group III: 2.25% peracetic acid. Group IV: 1% phytic acid. The experimental time periods were 1 min. These samples were prepared and then observed by using scanning electron microscopic analysis for the absence or presence of smear layer, there by analyzing their cleaning effectiveness in the coronal, middle, and apical thirds of the root canal system. Results In intergroup comparison, there was no statistically significant difference among the four groups. In intragroup comparison, there was no statistically significant difference between coronal and middle thirds. However, there were statistically significant differences between apical third versus both coronal and middle thirds in all tested groups. Conclusions The four tested final irrigation solutions can effectively remove the smear layer from the coronal and middle root canal thirds, but they did not completely remove the smear layer at the apical one third.