The effect of EDTA with and without ultrasonics on removal of the smear layer.

This study evaluated in vitro effectiveness of 17% EDTA with and without ultrasonics on smear layer removal. One hundred and five extracted premolars randomly divided into seven groups were instrumented with different final irrigating protocols: group A (Sal3US), saline for 3 minutes with ultrasonics; groups B (Na3) and C (Na3US), 1% sodium hypochlorite for 3 minutes without and with ultrasonics, respectively; groups D (ED3) and E (ED3US), 17% EDTA for 3 minutes without and with ultrasonics, respectively; and groups F (ED1) and G (ED1US), 17% EDTA for 1 minute without and with ultrasonics, respectively. Specimens were examined under scanning electron microscope and scored for smear layer and debris removal. Statistical analysis showed that groups with EDTA and ultrasonic irrigation, groups E (ED3US) and G (ED1US), had significantly more specimens with complete smear layer and debris removal. There was no significant difference between groups E (ED3US) and G (ED1US). A 1-minute application of combined use of EDTA and ultrasonics is efficient for smear layer and debris removal in the apical region of the root canal.