Effect of MTAD on Removal of Smear Layer

Objectives: To evaluate the effect of MTAD as final rinse on removal of the smear layer subsequent to primary irrigation with 1.3% sodium hypochlorite (NaOCl) during 10-minute instrumentation periods. Methods: Forty teeth were divided into 2 experimental groups, each containing 15 teeth and 1 positive control group of 10 teeth. After preparation, in the MTAD group, the root canals were flushed with 1.3% NaOCl solution during and MTAD was used as final rinse. In another experimental group, 5.25% NaOCl was used during instrumentation and 17% ethylenediamintetraacetic acid (EDTA) was used as the final rinse. In the positive control group, sterile distilled water was used for irrigation. The overall instrumentation period for each canal was 10 minutes. The amount of the smear layer was qualified according to the following criteria; (1) no smear layer: no smear layer on the surface of the root canal and all the tubules clean and open; (2) moderate smear layer: no smear layer on the surface of the root canal, but tubules containing debris; and (3) heavy smear layer: smear layer covering the root canal surface and the tubules. Data were analyzed by Kruskal-Wallis and Mann-Whitney tests. All statistical analyses were set with a significance level of α=0.05. Results: In the positive control group, debris and heavy smear layer covered the root canal surface and the tubules. In MTAD group, moderate smear layer covered the root canal surface and the tubules. In EDTA group, there was no smear layer on surface of canals. There were significant differences between groups (Ρ<0.0001). Mann-Whitney test showed significant difference between experimental groups(Ρ=0.01). Conclusions: The use of 5.25% NaOCl during instrumentation and 17% EDTA as the final rinse is more effective than using 1.3% NaOCl as primary irrigation and MTAD as final rinse on removal of the smear layer.