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Quantitative analysis of the effect of irrigation sequences on root canal wall dentin erosion Qian, Wei


Objectives: The purpose of the present study was to examine the effect on root canal wall dentin and compare the level of erosion caused by different irrigation sequences. Material and methods: Dentin specimens of the middle third of the root of extracted teeth with one root canal were instrumented and randomly divided into five groups. Each group was subjected to 17% ethylenediaminetetraacetic acid (EDTA), 17% ethylene-glycoltetraacetic acid (EGTA), or 10% citric acid (CA) and 5.25% sodium hypochlorite (NaOCl) varying the time of irrigation and the order of the irrigants. The blocks were prepared for and examined by scanning electron microscopy. Digital images at a magnification of 2000× were taken at randomized areas on the root canal dentin surface, and the area of tubule openings was measured by a semi-automatic method using image analysis software image-Pro Discovery 5.0. Results: Erosion of peritubular and intertubular dentin was detected when EDTA, EGTA or CA were used as the initial rinse (even for 30 s ), followed by 5.25% NaOCl. The area of dentin tubule opening increased markedly when compared to the sequences where NaOCl was used first, before the chelators or CA (P<0.05). An initial rinse with the chelators or CA for 5 min, followed by a final rinse with NaOCl, regardless of the duration of the NaOCl rinse (1 - 5 min), resulted in over 100% increase in the area of dentin tubule openings (P<0.01). Conclusions: Irrigation using 5.25% sodium hypochlorite after demineralization agent(s) on root canal wall dentin with smear layer causes marked erosion at the dentin surface.

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