Effect of the Duration of Irrigation with MTAD on Removal of Smear Layer and Creating Dentinal Erosion
Instrumentation of root canals produces a smear layer that occludes the dentinal tubules’ openings, so its elimination is desirable for irrigation solutions’ penetration into dentinal tubules. 5 min application of MTAD, after the initial irrigation with sodium hypochlorite, has been proposed as a clinical protocol. The aim of the present study was to evaluate the effect of 2 min irrigation with MTAD compared to its 5 min application, on removal of smear layer and creating dentinal erosion. 30 maxillary lateral incisors were randomly divided into four groups. After cleaning and shaping, final irrigation of canals was done using MTAD for 5 min, MTAD for 2 min, EDTA17% for 5 min and distilled water for 5 min. The remaining smear layer and dentinal erosion of each specimen were investigated by SEM. The nonparametric Kruskal-Wallis H-test and Mann-Whitney U (α = 0.05) were used to analyze the results by SPSS TM version 17 software. No statistically significant difference was shown between the cleanliness of the walls in 5 min MTAD and 2 min MTAD groups at coronal (p=0.26), middle (p=0.95) and apical (p=0.41) parts of the root canals. The dentinal erosion amounts were less in 2 min MTAD group than 5 min group, although the difference was not significant along the entire length of canals (p>0.05). Reducing the duration of final irrigation with MTAD from 5 to 2 minutes doesn’t negatively affect the smear layer removal ability, and at the same time, it can maybe reduce the degree of dentinal erosion.
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