[Quantification of mechanical versus ultrasonic technique in root canal preparation]

The previous investigations of the cutting efficacy of the paracanal dentine with different endodontic instruments have not quantified the amount of the tissue removed. The purpose of this study was to compare the effectiveness of various mechanical canal instrumentations with ultrasonic technique by measuring the weight loss of the root dentine. The investigation concerned 60 single-canal roots of freshly extracted human teeth. Each canal was primarily prepared with Beutel rock reamers, size 3, with penetration to the apex. After desiccation in the thermostat at 60 degrees C for 65 hours, roots were weighed using an electronic scale (Mettler, AE-163, West Germany) with a precision of 10(-4) grams. Samples were devided into six groups according to the endodontic instrument: (1)K-tupbe reamers, (2)K-files, (3) Hedstroem files, (4) giromatic cleansers, (5) giromatic files, (6) ultrasonic files. After having been prepared the root canal was thoroughly irrigated with 4 ml saline, redesiccated and reweighed. Ultrasonic instrumentation was the most effective in removing the root canal dentine compared with all mechanical techniques (t-test; p less than 0.005). The smallest amount of root canal dentine was removed by giro-files. This was statistically significant compared with K-files, giro-files and ultrasonic files. There was no significant difference among the other mechanical instruments used in this study.