A quantitative assessment of efficacy of various calcium hydroxide removal techniques.

This study evaluated the amount of calcium hydroxide [Ca(OH)(2))] remaining in canals after removal with various techniques including combinations of NaOCl with EDTA irrigation, hand filing, rotary instrumentation, or ultrasonics. The mesial canals of 12 mandibular molars were uniformly instrumented. Teeth were sectioned longitudinally along the length of the instrumented canals. Acrylic jigs were fabricated, allowing reapproximation of the opposing segments. After Ca(OH)2 placement into the canals, four techniques were used for its removal. In the first method, the master apical file was placed to working length in between two 5-ml rinses of NaOCl. The other three techniques combined with the first method either a 2.5-ml EDTA rinse, a rotary file (MAF size) to working length, or passive ultrasonication. Results showed that no technique removed all Ca(OH)2. Rotary and ultrasonic techniques, while not different from each other, removed significantly more Ca(OH)2 than irrigant only techniques. The irrigant only techniques were not different from each other.