Abstract
This study was designed to examine root canal cleansing effect produced by combined use of NaOCl and EDTA of various concentrations. The commercial preparation of each was analyzed quantitatively and diluted with distilled water ; the concentrations of NaOCl were 1.25%, 2.5% and 5%, and those of EDTA 1.875% 3.75% and 7.5%. Extracted maxillary and mandibular anterior teeth and mandibular premolars with the root canals untreated were employed. Enlarging and preparation of the root canals were made with K-files after the root canals were filled with distilled water. Then the root canals were given 1-minute irrigation with 2 ml of NaOCl holded in the syringe with a standard needle, and continuously with EDTA. In another group the same irrigation procedure was made with distilled water. Inner wall surfaces were observed through scanning electron microscope. The results were as follows : 1. when the canals were cleansed with water only, or with 1.25% NaOCl and 1.875% EDTA, smeared layer was observed ni mid-canal and root apex ; the root canal could not be cleansed sufficiently. 2. when the canals were cleansed with 2.5%-5% NaOCl and 3.75%-7.5% EDTA, cleansing effect was sufficient at mid-canal, but insufficient at root apex. 3. In order to increase cleansing effect on root canals, abundant use of the irrigation agents appears to be necessary.
