Endodontic retreatment: ultrasonics and chloroform as the final step in reinstrumentation.

Forty extracted teeth were instrumented using a step-back flare technique and obturated with gutta-percha and either AH26 or Roth's 801 sealer. After 3 months the canals were retreated by removing gutta-percha and sealer with hot instruments followed by chloroform and files. As a final step, the teeth were instrumented using ultrasonics with either chloroform or with NaOCl. Most teeth were well cleaned. No significant differences were found between sealer groups or between the two irrigants as to the ability to remove gutta-percha/sealer.