In vivo ultrasonic debridement forces in bicuspids: a pilot study

Hand instruments lead to application of excessive forces, resulting in extensive root substance removal. Ultrasonic debridement primarily removes accretions from root surfaces. However, there is a lack of information on procedural aspects of ultrasonic debridement. The purpose of the present study was to assess the forces applied by different therapists during ultrasonic root surface debridement of bicuspids in periodontal patients in vivo.

Ten dentists and 10 dental hygienists each debrided 1 aspect of a bicuspid with moderate chronic periodontitis using an ultrasonic curet. The forces applied were recorded using a piezo-electric receiver built into the handle of the ultrasonic curet, an electronic transducer, and an analogous writer. The force recordings were converted from millivolts into Newtons (N). Mean positive and negative forces were calculated for each therapist, and t tests were used to assess differences in these forces between dentists and dental hygienists.

The results showed that the mean positive force applied by dentists was 1.00 N (range 0.53 to 1.34 N). The corresponding mean value for dental hygienists was 0.77 N (range 0.20 to 1.22 N). The mean root debridement time was 110.2 seconds (range 38 to 165 seconds) for dentists and 90.8 seconds (range 38 to 244 seconds) for dental hygienists. The mean percentage of total debridement time used for positive force application by dentists was 76.1%, and for dental hygienists 63.9%. Negative forces impacting on the periodontal soft tissues were also recorded. These negative forces reached a mean of 0.16 N for dentists and 0.31 N for dental hygienists.

From these observations, it may be concluded that application of ultrasonic debridement therapy is highly subjective, and that dentists and dental hygienists may not be adequately trained to use these instruments optimally.