This study evaluates the effectiveness of subgingival scaling and root planing with longer shank, thinner blade, rigid curets compared to the standard rigid Gracey curet. A total of 35 non-molar teeth from 7 patients provided 140 root surfaces for evaluation; 52 root surfaces were instrumented with the rigid longer shank curets; 52 with the standard rigid Gracey curets; and 36 provided untreated controls. A bilateral matched design was utilized where contralateral teeth in the same arch were instrumented. Instrumentation was standardized at 15 minutes per tooth. Both scaled and unscaled teeth were extracted immediately after the experimental procedures. They were viewed under a stereomicroscope with a 0.10 mm grid to assess the percent of surface covered by calculus and unaltered cementum. The curet efficiency was also evaluated. The results indicated a significant treatment effect compared to the controls in relation to the percentage of residual calculus and curet efficiency. However, there was no significant difference between the rigid longer shank and standard rigid Gracey curets. There was a difference noted when tooth surfaces were evaluated. Mesial tooth surfaces had the least remaining calculus and demonstrated the best curet efficiency.