Dental hygiene and ergonomics

Ergonomics & Dental Hygiene

The Hazards of Dental Hygiene

People tend to think of dental hygiene as nice, clean and safe indoor work with nothing hazardous about it (except maybe when the patient gets the bill). Research, however, reveals ergonomic hazards in the job associated with musculoskeletal disorders. Some of these disorders are carpal tunnel syndrome, Trigger Thumb, de Quervain's stenosing tenosynovitis, and carpometacarpal osteoarthritis (Simmer-Beck, Bray, et al., 2006). In this essay we will discuss some of the causes of musculoskeletal disorders and the use of certain strategies to reduce their incidence.

Musculoskeletal disorders are a significant work related problem that warrants attention because researchers estimate 75% of dental hygienists experience hand problems during the course of their careers. As many as 56% develop symptoms of carpal tunnel syndrome. The Bureau of Labor Statistics supports these findings too (Simmer-Beck, Bray, et al., 2006). Dental hygienists are also exposed to certain body positions that produce stress and pain (Nelson & Jevack, 2001). The end result may be cumulative trauma disorder (CTD) when the body becomes unable to heal itself from "the long-term effects of repetitive motion, exposure to vibration, and/or mechanical stress" (Kerschbaum, 1997, p. 162). Some of the "social side effects" of developing these problems are lost work time, loss of income, higher medical bills, more workmen's compensation claims and an inability to complete daily tasks that used to be easy. Perhaps of greatest concern, is the prospect of early retirement or that retraining for a change of career could be required. Dental hygienists can do much to prevent musculoskeletal disorders. Because developing a disorder can be so costly, both humanly and financially, prevention should be a priority.

The pinch grip in which an instrument is grasped and pressure applied using the fingertips is a common risk factor in the dental office. When the pinch grasp is used, there is increased pressure in the carpal tunnel. Increased exertion on the finger flexor tendons also occurs when pressure is applied. While pinching, mechanical movements happen at the wrist and finger joints. Researchers (Simmer-Beck, Bray, et al., 2006) state, "The tensile force to oppose these movements is much higher than the normal force acting on the fingers when normal force is exerted with only the finger tips... It has been calculated that one pound of pinch between the thumb and index finger will produce six-to-nine pounds of pressure at the basal joint to the thumb" (p. 81). Researchers recommend dental instruments and dental mirrors have large diameter padded handles in order to reduce the effect of the pinch grip.

Researchers (Simmer-Beck, Bray, et al., 2006) did a study to test the effects of the diameter and weight of bigger handles with padding. They looked at the interaction of three muscles in the hand and forearm when the pinch grip is being used. The subjects of the research were dental hygiene students in their final semester of study who had no history of musculoskeletal disorders in the past 30 days and no history of carpal tunnel syndrome or hand surgery. Electrodes were used in conjunction with electromyography with lines fed into a satellite computer. The subjects used a modified pinch grasp while looking down into a typodont in a chin-up position. The researcher state that "altering the weight, diameter, and padding of dental hygiene instrument handles appears to have an effect on muscle activity" (p. 90) but more research is needed to learn more. They suggest that handles on the instruments should be tailored to fit each individual hygienist.

Ultrasonic instruments reduce the force levels compared to manual scaling, and so they have been welcomed as an ergonomic improvement. They lessen the amount of force and flexion needed and extension of the hand. But vibration is increased with ultrasonics and may balance out these advantages, so again, more research is needed (Nelson & Jevack, 2001; and Michalak-Turcotte, 2000).

Dental hygienists do not always practice proper ergonomics when they treat patients, even though they are taught the importance in school (Nelson & Jevack, 2001). This man be due to fatigue or trying to expedite a difficult procedure. They sometimes repeatedly position their bodies incorrectly in prolonged awkward positions (Michalak-Turcotte, 2000; Liskiewicz & Kerschbaum, 1997). Researchers (Nelson & Jevack, 2001) conducted a pilot study, a survey among dental hygienists and dental hygiene students. They found that 99% of licensed hygienists reported having experienced pain or discomfort while treating patients! The hygienists reported pain in the neck and shoulder region, hands, fingers, and lower back. Nelson & Jevack (2001) concluded, "Due to the number of students and licensed dental hygienists who experience pain...proper ergonomics should be enforced in dental hygiene education for future physical wellness and career longevity among dental hygienists" (p. 119).

The researchers (Nelson & Jevack, 2001) suggest -- as others have -- that instruments be redesigned, but also, the working environment needs to be improved for "better adjustments on patient chairs such as adequate height and tilt adjustments, operator stools with support for arms, adequate work breaks, proper lighting angles, space for legs under the patient chair, early medical intervention for symptoms, and angled instruments to reduce wrist flexion" (p. 119). Michalak-Turcotte (2000) recommends that an ergonomic plan be developed for each practitioner. She states, "The objective of an ergonomic program is to fit the job to the worker, rather than the worker to the work" (p. 41). Therefore, each hygienist needs a plan that is specifically suited to him/her and which includes attention to temperature, lighting, nose, equipment design, and workstation design. Due to the repetitive nature of their work, they are at a higher risk for lower back, neck, shoulder, hand, and wrist pain than other health care occupations. This makes it imperative that ergonomic plans be developed and implemented.

Michalak-Turcotte (2000) points out the practice of dental hygiene varies from person to person. Each will have different equipment and instruments requiring different maintenance, different policies about scheduling patients, varying length of appointments, etc. In other words, every practitioner has a different stress level. They suggest alternating patients so that heavy calculus patients don't come in consecutively and planning ways to reduce stress. They point out that dental hygienists usually work sitting down while the patient is usually in a supine position. The hygienist has to use wrist flexion and extended shoulder abduction.

Working in a fixed position can lead to "static loading" on the neck and shoulders.