In vivo scaling and root planing forces in molars

The purpose of the present study was to assess in vivo scaling and root planing forces in molars of periodontitis patients. Ten dentists and 10 dental hygienists scaled and root planed the mesial and distal aspect of one first molar, using Gracey curets 11/12 and 13/14. Scaling and root planing forces were recorded using a piezo-electric receiver, an electronic transducer, and an analogous writer. The forces were recorded in mV and converted into Newtons (N). Three different types of forces were recorded: positive forces during working strokes and positive and negative forces during preparation of working strokes. Multivariate repeated measures analysis of variance was used to assess differences in force between curet types. The mean positive scaling forces exerted with curet 11/12 were statistically significantly (P = 0.0005) greater than the corresponding forces exerted with curet 13/14 in all therapists. The mean positive root planing forces applied with the curet 11/12 were significantly (P = 0.0008) greater than the forces exerted with curet 13/14. The mean positive interstroke forces did not differ between curet 11/12 and 13/14. The mean negative interstroke forces impacting on the soft tissues exerted with curet 11/12 did not significantly differ from curet 13/14 during scaling and during root planing. Therapists differed significantly among themselves for each type of positive and negative force (P < 0.001 in all cases). These results suggest that the extent of instrumentation given to root surfaces in molars depends more on the therapist and on the molar aspect being treated than on the needs of a specific site.