FORMATION OF SMEAR LAYER AND SMEAR PLUGS VARIES WHEN USING ULTRASONIC TIPS UNDER VARIOUS CONDITIONS

Abstract

Various types of ultrasonic tips are used with microscope to remove the debris in root canals. However, even after removal of debris by microscope, we can not clearly see the surface condition of the root canal. The present study was conducted to clarify differences in the smear layer formed when using an ultrasonic tip under various conditions (tip type, with/without water, and power level). Sixty sectioned single-rooted specimens without smear layer and smear plugs were divided into 12 groups based on combinations of tip type (diamond tip, stainless steel tip), use/non-use of water, and power level. The ultrasonic tip was gently (5-10 g) pushed against the canal wall and moved vertically along the long axis for 5 s. The root canal surface and cut surface of the specimens were observed by SEM, and then scored. Significant differences were observed in the presence of a smear layer between the control and all test groups (p<0.01). A stainless steel tip used at lowest power with water produced the least amount of smear layer. Smear plugs were frequently formed when the root canal was shaped using a diamond tip with water. The smear layer and smear plug formation varied when using ultrasonic tips under various conditions.