Effects of ultrasonic root-end preparation on microcrack formation and leakage

Root-end preparations made with conventional ultrasonic (CUS) tips, diamond -coated ultrasonic (DUS) tips, and high-speed stainless-steel burs (HSB) we re compared for the incidence of microcracks and dye leakage. One hundred t wenty incisors were instrumented, obturated, and had 3 mm resected from the ir apices. Sixty teeth were used for microcrack evaluation before and after root-end preparation with CUS, DUS, or HSB. Three types of microcracks wer e observed: intracanal, extracanal, and communicating. Four of the five cra cks observed after root resection (before root-end preparation) were of the extracanal or intracanal type. After root-end preparation, 19 of the 41 ne w microcracks that developed were the communicating type. There was no sign ificant difference among CUS, DUS, or HSB for the number or type of cracks. Of the remaining 60 resected teeth, 25 were prepared with DUS, 25 with CUS , and 10 served as controls. All of the DUS and CUS teeth were filled with Super-EBA. Dye penetration was measured after immersion in Pelikan ink for 5 days. The dye penetration difference between DUS and CUS was not signific ant.