Objectives The objective of the presentin vitro study was to evaluate the canal wall smear layer removal capacity and mineral content distribution of root canal dentine after irrigation with QMix, 7% maleic acid (MA) and 17% ethylenediaminetetraacetic acid(EDTA). Methods Forty single-rooted teeth were subjected to root canal instrumentation and divided into four groups:  7% MA + 2.5% sodium hypochlorite (NaOCl),  17% EDTA+ 2.5% NaOCl,  QMix + 2.5% NaOCl and  0.9% saline (negative control). After irrigation, the teeth were examined byscanning electron microscopy (SEM) to determine the presence or absence of smear layer. Formineral content assessment, 40 root-halves were divided into four groups and treated with 7% MA, QMix, 17% EDTA and saline. Mineral content was evaluated using SEM-energy dispersive X-ray analysis. Results There was no significant difference between QMix, MA and EDTA in removal of smear layer from coronal and middle third of the canal spaces. In the apical third, MA performed better. Calcium was decreased more with QMix with no difference between MA and EDTA. Phosphorous was reduced more with MA and QMix than EDTA with no difference between MA and QMix. Similar result was observed with magnesium level. Carbon was reduced more with EDTA with no difference between QMix and MA. Oxygen was reduced significantly more with MA with no difference between QMix and EDTA. Conclusion 7% MA had superior smear layer removal ability compared with QMix and 17% EDTA. Calcium level was decreased more with QMix while phosphorus level was decreased more with 7% MA and QMix respectively. Clinical significance The present study highlights the effect of newer chelating agentson smear layer removal and decalcification of root canal dentine, which is required for disinfection of the root canal space and maintenance of the structural integrity of the teeth.
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