Clinical Evaluation of Tooth Reduction Using Piezotome

The purpose of this study was to compare and assess ultrasonic tooth preparation using an air-turbine and micro-motor. Twelve human extracted molars were used in this study. Each crown of the molar was roughly prepared from complete veneer crown and the cervical margin was divided equally into three-120° angles along the line of cement-enamel junction (CEJ). Three devices: Piezotome (SATELEC ACTEON, France), an air-turbine and a 1:5 speed friction grip (FG) micro-motor were used to finish the chamfer margin of each crown. After preparation, the margin continuity, sharpness and roughness, unevenness of prepared surface, were observed by a microscope with 8x magnification. Evaluation was made by 3 independent doctors evaluating the results using 3 levels and compared by the Kruskal-Wallis test. Piezotome showed excellent evenness and the evaluation results were highly significant compared with the micro-motor and significant compared with the air-turbine. Preparation time was analyzed by one way ANOVA and post hoc multiple comparison. The total preparation time of Piezotome was significant longer than the other two. Regarding the results of the simulated preparation test of the subgingival margin for complete veneer crowns using extracted human molars, completion of the cervical margin by Piezotome took more longer, but it could obtain a better cervical margin and this method has sufficient clinical value.