Date of Award

Spring 2007

Document Type


Degree Name

Master of Science (MS)


Dental Hygiene


Dental Hygiene

Committee Director

Susan Lynn Tolle

Committee Member

Michele L. Darby

Committee Member

Martha Walker

Call Number for Print

Special Collections LD4331.D46 C67 2007


This study was conducted to determine the effects of five different finger rest positions, (fulcrums: opposite arch, standard intra-oral, basic extra-oral, cross arch and finger on finger) on the muscle activity of four forearm muscles, (extensor carpi radialis longus, flexor carpi ulnar is, biceps brachii and pronator teres) during a simulated periodontal scaling experience. A convenience sample of 32 consenting right handed senior dental hygiene students who met inclusion criteria participated. The 32 students had no history of injuries or disabilities to the right arm, wrist, or hand. Pre-test maximum voluntary isometric contraction (MVIC) scores were obtained prior to scaling. Using a 4 x 5 counterbalanced research design, each participant used a Premier Gracey 11/12 curet to scale up to one cc of artificial calculus from the mesiobuccal surfaces of first permanent molar typodont teeth (Nos. 3, 14, 19, and 30). Five different typodonts were set up for each participant with a different fulcrum randomly assigned for use on each typodont. Each participant scaled what calculus they could in a controlled, simulated situation for up to one minute per tooth using the randomly assigned fulcrum. While scaling, participants' muscle activity was measured using surface electromyography (sEMG). Two-way ANOV A with repeated measures revealed no statistically significant interaction effect between area of the mouth scaled, muscle activity, and fulcrum used. Results revealed that following 20, one-minute scaling sessions using a hand instrument to remove artificial calculus, there was similar muscle activity generated. While scaling, forearm muscle activity was least when using the opposite arch fulcrum and most when using the cross arch fulcrum. Regardless of where scaling started more muscle activity occurred in the maxillary right quadrant and the least in the mandibular left. Based on the results, similar muscle activity is produced while scaling when using all of the five fulcrums tested in each area of the mouth. Clinicians appear to experience minimal ergonomic advantages in terms of fulcrum 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.


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