Effects of Five Different Finger Rest Positions on Arm Muscle Activity During Scaling

Abstract

With the increased incidence of repetitive strain injuries in dental practitioners, dental hygienists must make informed decisions regarding instrumentation practices and procedures. The use of finger fulcrums may impact on muscle activity when scaling and influence the ergonomic practice of dental hygiene. The purpose of the research was to determine the effects of 5 different finger rest positions on forearm muscle activity during a simulated periodontal scaling experience. A convenience sample of 32 consenting senior dental hygiene students who met inclusion criteria participated. Using a 4 x 5 counter balanced research design each participant used a Gracey 11/12 curet to scale up to one cc of artificial calculus from the first permanent molar typodont teeth (#3, 14, 19, 30). Five different typodonts were set up for each participant with a different fulcrum randomly assigned for use on each typodont. Muscle activity was measured by surface electromyography. Data analysis with 2-way ANOVA revealed no statistically significant interaction effect between area of the mouth scaled and fulcrum used. The upper right quadrant produced the most muscle activity (p=0.0101) and the lower left quadrant produced the least (p=<.0001). When comparing the overall muscle activity generated with each fulcrum only the cross arch fulcrum when compared to the opposite arch fulcrum produced statistically significant results (p=0.0110). Based on the results of this simulated clinical study similar muscle activity is produced while scaling when using all of the 5 fulcrums tested in each area of the mouth. Clinicians appear to experience minimal ergonomic advantages in terms of fulcrums used and area of the mouth scaled during a simulated scaling experience. Characteristics of the patient may be more important when choosing a fulcrum than the amount of muscle activity generated.