A Laboratory Investigation of the Effectiveness of Different Acids in Removing Mineral Trioxide Aggregate From Simulated Root Canals

The aim was to compare the effectiveness of acids in removing MTA from root canals. Fifty acrylic blocks were filled with MTA and divided into groups - 10% hydrochloric acid; 10% citric acid; 2% acetic acid; 2% carbonic acid and 20% tartaric acid. MTA was removed with the acids, plus ultrasonic tips and rotary files. Outcomes were measured as pre- and post-operative weight differences, luminance differences and working time to regain length or form ledges. Weight differences varied significantly - citric acid was highest; hydrochloric acid was lowest and others were not statistically different from each other. Luminance did not differ significantly between groups but varied significantly with distance from the apex - hydrochloric acid and carbonic acid were lowest at 1 mm from the apex. Working times differed significantly - hydrochloric acid took longer than other acids except citric acid. Overall, the most effective acid was citric acid. The least effective was hydrochloric acid.