Smear Layer Removal Methods Compared

Using scanning electron microscopy (SEM), a study evaluated the efficacy of smear layer removal using chitosan compared with different chelating agents. The root canals of 25 canine teeth were prepared using a crown-down technique, irrigated with 1% sodium hypochlorite, and randomly divided into 5 groups based on final irrigation: 15% Ethyl­ene­dia­minetetra­acetic acid (EDTA), 0.2% chitosan, 10% citric acid, 1% acetic acid, and control (without final irrigation). The total volume of each chelating solution was collected from the canals and analyzed for quantification of calcium ions in the solutions. The roots were split longitudinally and examined by SEM for evaluation of smear layer removal in the middle and apical thirds. Cleaning scores were attributed and analyzed statistically. It was found that the EDTA, chitosan, and citric acid groups had similar smear layer removal capacity with a significant difference (P < .05) from the acetic acid and the control group. There was no significant difference (P > .05) between the smear layer remaining in the middle and apical thirds. The highest calcium ion concentration was observed with EDTA (121.80 ± 5.13) and chitosan (104.13 ± 19.23), with no significant difference. The lowest calcium ion concentration was obtained with acetic acid (25.62 ± 7.68), while citric acid (70.38 ± 11.15) had intermedi­ate results, differing significantly from the other solutions (P < .01). The study concludes that 15% EDTA, 0.2% chitosan, and 10% citric acid effectively removed smear layer from the middle and apical thirds of the root canal; 15% EDTA and 0.2% chitosan had the greatest effect on root dentin demineralization, followed by 10% citric acid and 1% acetic acid.
(Source: International Endo­dontic Journal, accepted manuscript online July 26, 2012)
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