Purpose: To compare the effect on root surfaces of three ultrasonic scalers to each other and to a periodontal curet.
Materials and methods: Forty extracted teeth were washed and embedded in acrylic resin leaving one entire coronal-apical tooth aspect exposed. The teeth were divided between four treatments: piezoelectric A - Group A, piezoelectric B - Group B, magnetostrictive - Group C, hand instrumentation with a curet - Group D. A single experienced operator simulated clinical instrumentation over a 9 mm square area on each tooth until the surface was judged smooth by the operator. Three evaluations were used in the study: (1) root tracings with a surface roughness meter to determine the roughness average (Ra) and roughness maximum (Rmax) in microns, (2) use of a new EXD 11/12 explorer to assess planed roots and (3) visual evaluation of the root surfaces through a stereoscopic microscope (X 20). During examinations 2 and 3, root surfaces were assigned to one of four "smoothness categories" by the examiners. Data for evaluation 1 was analyzed by ANOVA. Data from evaluations 2 and 3 were analyzed using the Kruskal-Wallis non-parametric test.
Results: The mean Ra and Rmax were not significantly different between the four groups. The results from both clinicians' examinations showed a significant difference in the four groups (P=0.001). The curet produced the smoothest surfaces, the two piezoelectric instruments produced the next smoothest surface and the magnetostrictive instrument the least smooth root surfaces.