Odds and ends

July 1, 2010
>Six months ago, the Comfort Zone column went on a stroll down memory lane. Ergonomics — the topic that was the original foundation for this column — has been the focus of every column this year.

by Anne Nugent Guignon, RDH, MPH
[email protected]

Six months ago, the Comfort Zone column went on a stroll down memory lane. Ergonomics — the topic that was the original foundation for this column — has been the focus of every column this year. The comfort zone concept embodies everything which improves a clinician’s physical and mental performance. The comfort zone also includes any and every technique or product that provides comprehensive, comfortable services for our patients.

Study after study demonstrates that repetition, force, increased pinch/grip, precision movements, constrained working environments, static postures, and non-neutral positions are factors that contribute to the risk of an upper extremity workplace-related musculoskeletal disorder (WRMSD).1-5 Research also shows WRMSDs are more common in females than males, and women are more prone to neck and upper extremity disorders.3-5 Wrist injuries alone, often initiated by gripping or turning movements, account for nearly 9% of all WRMSDs reported in the United States.6 The risk for injuries rises when forceful procedures are performed with a deviated wrist, a common posture used by many hygienists.7

It’s the little things that make or break our day. So this column is devoted to a variety of ways to reduce the stress of precision gripping on the variety of dental tools used in clinical practice. A precision grip is defined as a postural grasp where an object is manipulated between the tips of the fingers (including the pads and sides of the fingers) and the thumb. Nearly all dental hygiene instrumentation uses a precision grip as compared to a force grip used to hold an object such as a baseball bat or a hammer handle. An ideal precision grip needs minimal hand movement to activate a tool that uses fingertip control and allows the user to initiate a quick release. 6,8

  • Surface texture — The oral cavity is a wet field. Moist, slick surfaces require a much tighter pinch/grip — a significant risk factor for developing a WRMSD. Texture equals traction, a coefficient of friction. Surface texture on hand instruments, as well slow-speed, high-speed, or ultrasonic handpieces, is critical.6,8

Adaptive grips made from autoclavable, medical-grade silicone not only enlarge handle diameter but also reduce pinch grip.9-11 Many gloves now feature lightly textured surfaces on the fingertips or across the entire palm.12 Using a combination of textured surfaces allows clinicians to use a more relaxed grasp.

  • Balance — Working with a balanced tool is another way to improve comfort. While the weight of a particular instrument or handpiece is important, balance plays an even bigger role in creating a safe working environment. Balanced tools keep our hands and fingers relaxed. It doesn’t take much effort or a tight pinch grip to hold onto a well-made, balanced handpiece or instrument. 6-8
  • Cords — Cord weight and torque present other annoying problems. Old, heavy coiled hoses tug on the wrist, hands, and fingers, creating stressful wrist postures. These cords make it impossible to use a light grasp or maintain a healthy, neutral wrist posture. Replacing heavy, coiled cords with new lightweight, straight hoses is a small price to pay for increased comfort and safety.7

Manufacturers are paying attention to ergonomics as well. Most newer ultrasonic scaler handpiece hoses are quite a bit longer than models made years ago. This increase in length can contribute to overall weight, 6,8 but some companies are using innovative, lightweight, flexible, and easy-to-clean materials to cover the hose. These new materials dramatically reduce cord torque at the handpiece/hose intersection.

  • Swivels — Cord torque also magically disappears if a device has a swivel mechanism. Instead of having the clinician’s body adapt the tool to a surface, swivels let us effectively adapt the tool to the clinical challenge — a basic ergonomic tenet. Swivels allow one to work effectively without placing additional strain on the fingers, hands, wrists, forearms, and elbows.6,8 Swivel technology is now built into magnetostrictive ultrasonic scaling inserts, as well as both polishing and ultrasonic handpieces.

A complete 360-degree swivel is available in both ultrasonic scaling inserts and polishing devices. Rotation in an ultrasonic scaler handpiece is slightly less due to fluid irrigant tubing and wiring components. Swivels are built into many air-driven polishing handpieces. The most popular designs feature a fingertip-activated swivel, but there are also handpieces made with mid-body or hose-end swivels.

A swivel alone is not the total answer. Look for devices that have swivel mechanisms that respond quickly and uniformly to touch and have a fluid movement that does not hesitate or catch. Swivels should feel natural and not rotate too quickly or resist the most delicate or discrete fingertip movement. 6,8

Our bodies are not disposable tools. Whether one plays a violin, scales a tooth, or digs ditches for a living, it is critical that we take care of our physical health. Ultimately, we are responsible for researching the root causes of workplace-related injuries and taking the necessary measures to create a safe working environment. It’s our body, our professional career, and our life that is at stake and we must work diligently to build our own comfort zone.


  1. Latko WA, Armstrong TJ et al. Cross-sectional study of the relationship between repetitive work and the prevalence of upper limb musculoskeletal disorders. Am J Ind Med. 1999 Aug;36(2):248-59.
  2. Pascarelli EF, Hsu YP. Understanding work-related upper extremity disorders: clinical findings in 485 computer users, musicians, and others. J Occup Rehabil. 2001 Mar;11(1):1-21.
  3. Nordander C, Ohlsson K et al. Risk of musculoskeletal disorders among females and males in repetitive/constrained work. Ergonomics. 2009 Oct;52(10):1226-39.
  4. Nordander C, Ohlsson K et al. Gender differences in workers with identical repetitive industrial tasks: exposure and musculoskeletal disorders. Int Arch Occup Environ Health. 2008 Aug;81(8):939-47.
  5. Fransson-Hall C, Byström S, Kilbom A. Self-reported physical exposure and musculoskeletal symptoms of the forearm-hand among automobile assembly-line workers. J Occup Environ Med. 1995 Sep;37(9):1136-44.
  6. Pheasant S, Haslegrave CM. Bodyspace: anthropometry, ergonomics, and the design of work. Bocca Raton: Taylor and Francis. 2006
  7. Nunn PJ. Posture for dental hygiene practice. In DC Murphy (Ed.), Ergonomics and the dental care worker.1998. Washington, D.C.: Amer Pub Health Assn.
  8. Helander M. A guide to human factors and ergonomics – 2nd ed. Boca Raton: Taylor & Francis, 2006.
  9. Simmer-Beck M, Bray KK et al. Comparison of muscle activity associated with structural differences in dental hygiene mirrors. J Dent Hyg. 2006 Winter;80(1):8. Epub 2006 Jan 1.
  10. Dong H, Loomer P et al. The effect of tool handle shape on hand muscle load and pinch force in a simulated dental scaling task. Appl Ergon. 2007 Sep;38(5):525-31.
  11. Simmer-Beck M, Branson BG. An evidence-based review of ergonomic features of dental hygiene instruments. Work. 2010 Jan 1;35(4):477-85.
  12. Laroche C, Barr A et al. Effect of dental tool surface texture and material on static friction with a wet gloved fingertip. J Biomech. 2007;40(3):697-701.

Anne Nugent Guignon, RDH, MPH, provides popular programs, including topics on biofilms, power driven scaling, ergonomics, hypersensitivity, and remineralization. Recipient of the 2004 Mentor of the Year Award and the 2009 ADHA Irene Newman Award, Anne has practiced clinical dental hygiene in Houston since 1971.

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