Retrograde seal in ultrasonically prepared canals.

The sealing ability of various retrofilling materials was compared. The root canals of 85 single-rooted teeth were cleansed and obturated with gutta-percha without sealer using lateral condensation. The apical 3 mm of the roots were resected and divided into positive control, negative control, and five experimental groups. The experimental teeth received root-end cavity preparation to 3 mm depth using an ultrasonic retroprep tip. The retrocavities were dried and divided into five groups to receive the following materials: amalgam with varnish, amalgam with Clearfil Liner Bond II, thermoplasticized gutta-percha (TGP) with sealer, Ketac-fil, and Super-EBA. After immersion in India ink for 7 days, the roots were demineralized, cleared, and evaluated for dye leakage under a stereomicroscope. Statistical analysis showed that Super-EBA, Ketac-fil, and TGP with sealer demonstrated less leakage than amalgam with varnish and amalgam with Clearfil Liner Bond II (p < 0.05). Super-EBA also leaked significantly less than Ketac-fil or TGP sealer (p < 0.05). No significant difference was found between Ketac-fil and TGP or between the two groups filled with amalgam (p > 0.05).