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Effect of dental tool surface texture and material on static friction with a wet gloved fingertip.

Laroche-C; Barr-A; Dong-H; Rempel-D
J Biomech 2007 Mar; 40(3):697-701
Hand injuries are an important cause of pain and disability among dentists and dental hygienists and may be due to the high pinch forces involved in periodontal work. The pinch forces required to perform scaling may be reduced by increasing the friction between the tool and fingers. The purpose of this study was to determine whether modifying the tool material, surface texture, or glove type altered the coefficient of static friction for a wet gloved finger. Seven tools with varying surface topography were machined from 13mm diameter stainless steel and Delrin and mounted to a 6-component force plate. The textures tested were a fine, medium and coarse diamond knurled pattern and a medium and fine annular pattern (concentric rings). Thirteen subjects pulled their gloved, wet thumb pad along the long axis of the tool while maintaining a normal force of 40N. Latex and nitrile gloves were tested. The coefficient of static friction was calculated from the shear force history. The mean coefficients of static friction ranged from 0.20 to 0.65. The coefficient of static friction was higher for a smooth tool of Delrin than one of stainless steel. Differences in the coefficient of static friction were observed between the coarse and medium knurled patterns and the fine knurled and annular patterns. Coefficients of static friction were higher for the nitrile glove than the latex glove for tools with texture. These findings may be applied to the design of hand tools that require fine motor control with a wet, gloved hand.
Biological-effects; Dentistry; Dentists; Engineering; Ergonomics; Exposure-methods; Hand-injuries; Hand-tools; Mathematical-models; Musculoskeletal-system; Musculoskeletal-system-disorders; Physiological-effects; Physiological-measurements; Physiological-response; Risk-analysis; Risk-factors; Statistical-analysis; Surface-properties; Author Keywords: Friction; Finger; Tool; Dental; Scaling
David Rempel, MD, MPH, Division of Occupational Medicine, Department of Medicine, University of California, San Francisco, 1301 South 46th St., Building 163, Richmond, CA 94804
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Journal Article
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Journal of Biomechanics
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University of California, Berkeley
Page last reviewed: January 29, 2021
Content source: National Institute for Occupational Safety and Health Education and Information Division