The mesiolingual canal was enlarged coronally with #2 Largo bur and ultrasound (Satellec with a zirconium coated tip #5C, power setting at 7) to the broken instrument. The canal was occasionally irrigated with NaOCl for cleaning and temperature control. The instrument was then removed with endodontic ultrasound (Satellec with a #25 K-file, power setting at 4 and 7).