SCANNING ELECTRON-MICROSCOPIC EVALUATION OF THE CLEANLINESS OF A NEW ULTRASONIC ROOT END PREPARATION

Recently introduced ultrasonic instrumentation techniques for root end preparation hale revolutionized the field of endodontic surgery. The specially designed rips offer improved access to the root end and crea te more conservative root end preparations while decreasing the amount of retained debris. This study compared the cleanliness of root end p reparations made using ultrasonic instrumentation with that of those p repared in a traditional manner using a microhandpiece bur. We used 10 extracted maxillary human premolars and molars. After cleaning, shapi ng, and obturation of the root canals, a 3 mm root end resection perpe ndicular to the long asis of the root was pet-formed with a carbide fi ssure bur. The roots were randomly divided into two groups and root en d preparations were made using the two aforementioned techniques. The roots were longitudinally split and sputter-coated with gold for scann ing electron microscopic study. Three independent dentists used a stan dardized grading system to evaluate the cleanliness of the root end pr eparations. The ultrasonic preparation had significantly less superfic ial debris and a thinner smear layer than the microhandpiece preparati on (p < 0.05). There were no significant differences between the canal and isthmus portions of the root end preparations within each group i n either superficial debris is or smear laver. This indicates that cle aner surfaces for root end cavities are created using ultrasonic retro tips than using microhandpiece burs.