The Role of Ergonomics in Dentistry

In Greek, “ergo” means work and “nomos” means natural laws or systems. The term ergonomics was coined by British psycholo¬gist Hywel Murrell, at the 1949 meeting at the United Kingdom admiralty, which later led to the foundation of the ergonomic society. The international ergonomic association defines ergonomics as, the scientific disci¬plines concerned with the understanding of interactions among humans and other elements of a system, and the profession that applies theory, principles, data, and meth¬ods to design in order to optimize human well-being and overall system performance. (International Ergonomic Association http://www.iea.cc)

The neutral position is the recommended positioning of the clinician's body while performing the everyday procedures. This position is safe for work and decreases the risk of musculoskeletal disorders. The risk of injury is higher when the clinician's position deviates from the neutral position.

Researches show that over 80 percent of the dental professionals complain of pain in the upper body and back. This pain is associated with the poor posture and movements during the dental procedures. The good news is that these problems can be avoided by increasing awareness of the postures used during work, redesigning the workstation to promote neutral positions, examining the impact of instrument use on upper extremity pain, and following healthy work practices to reduce the stress of dental work on the practitioner’s body.

This article introduces the signs, symptoms, and risk factors of MSDs along with guidelines about how to prevent further injury. The article also discusses the important issue of posture and offers ten ways to improve your posture to allow you to work with comfort, efficiency, and ease.

Prior to 1985, the low back pain was the most commonly reported musculoskeletal disorder (MSD) or repetitive injury for dentists and dental hygienists. Since then, there has been a rise in MSDs from extended workdays, awkward postures, prolonged standing/unsupported sitting, and a host of other problems caused by poorly designed workstations, improper work habits, and instruments that are difficult to manipulate. The current workstation in most dental offices requires that the practitioner lean forward, flex his neck forward and laterally, hold his shoulders abducted and his arms flexed, with this position being held statically for most of the workday. Dentists need to tightly grip thin, sharp instruments and make a high volume of short, forceful movements with the muscles of their wrists and hands to treat heavy calculus and other conditions. The human body is not built to handle these kinds of stresses, and the positions in which dentists repeatedly put themselves through their workplace them at great risk for developing MSDs.

What Are Musculoskeletal Disorders?

An MSD is an injury of the muscles, nerves, tendons, ligaments, joints, cartilage, blood vessels, or spinal discs. These disorders can occur from a single incident, such as lifting a heavy weight, or can develop gradually from repeated stress on a part of the body. MSDs can affect any part of the body, but most commonly occur in the back, neck, shoulder, elbow, and wrist

The elements of an improper workstation setup force the dental practitioner to assume many harmful postures when performing various procedures on the patient. These positions put pressure on nerves and blood vessels, cause excessive strain on muscles, decrease circulation, and cause wear and tear on the joint structures. When you notice yourself working in awkward positions, you should change positions and assume healthy, ergonomic postures to avoid injury.

The workstation setup is vitally important because it determines the postures that must be taken and sustained by the dentist when working with patients and how the practitioner must reach to retrieve the necessary instruments. The workstation is composed of the dentist’s/dental hygienist’s chair, the patient’s chair, the delivery system, and the cleaning/charting area. When the workstation is set up improperly or is not adjusted to the individual dentist’s dimensions, it can cause the dentist to put excessive stress on his/her body with each movement, and these positions are repeated throughout the day. By being aware of what causes you to assume harmful postures, you can begin to work on correcting any misalignments needed to put yourself in the proper posture to perform your work effectively.

Dentists and hygienists are required to perform physically demanding work with the muscles of their arms and hands almost continuously throughout the day while trying to provide the highest quality of care for each patient. They are often overbooked with heavy calculus patients scheduled back-to-back, requiring them to use excessive force with their hands without rest breaks in between. Using the hygiene patient as an example, the recommended amount of time that should be spent with each patient is 50 to 60 minutes for an adult and 35 minutes for a child. If there is time left over, the practitioner should perform exercises and stretches to increase circulation, decrease muscle tension, and prepare the body for the next patient. The procedures of probing, scaling, root planning, cleaning, polishing, and flossing the teeth are hand intensive and repetitive in nature, and when these are done in an improperly set up workstation for that individual practitioner the chances of developing repetitive injuries are multiplied. To prevent repetitive injuries, it is better to pace yourself and schedule fewer patients per day, with rest breaks in between to allow yourself time to heal. During your break, you should perform nonstressful exercises, take walks, stretch, perform stress relaxation techniques, or just rest your hands.

Make sure that no more than half of the patients on a certain day are heavy calculus patients to spread the stress on your hands over many days.

Dentists must look at the way they work, learn to pace themselves, and rotate between a variety of tasks and positions to give their muscles a break and allow them to work a full day without causing cumulative damage to their bodies. Sedentary work, like that performed in dentistry, concentrates work stress onto certain muscles and builds tension in our bodies. By alternating between positions, you shift the stress onto different muscles, increase your circulation, and lessen the amount of fatigue from your work. By switching sides of the patient and altering the position of your delivery system, you will use your muscles in different ways, which will spread the stress over other parts of your body.

The instruments that dentists and hygienists use pose a special threat to the muscles and tendons of their arms and hands. They are required to forcefully grip thin instruments and make constant, precise movements with the small muscles of their hands and forearms throughout various procedures. Some of the most hand-intensive procedures that must be performed by dental practitioners are (1) probing, which requires high forces to be exerted by the hands; (2) scaling, which involves short strokes and the application of strong pressure; and (3) root planning, which requires longer strokes and more extensive ranges of motion in the wrists.

Purchase high-quality instruments with large diameter handles that are easy to grip and balanced for less forceful manipulations. The cost of good instruments pays for itself when you factor this amount out over the number of years the instrument will be used.

Many problems have been noted with dental instruments, including the small diameter of the handles (usually between 3/16” to 4/16” in diameter), which requires a tighter grip to hold the instrument. Many instruments were designed with function in mind, without consideration of ergonomic factors or the possible effect on the body, and are unbalanced and require increased muscular force to manipulate.

When dental instruments are not regularly maintained and kept sharp, more pressure may need to be applied to remove plaque and clean teeth. Additional problems are created by tight gloves and wristwatches, which decrease circulation and make it more difficult to manipulate dental tools. Instruments provide the practitioner/patient interface, but their use involves a number of harmful positions that greatly increase the practitioner’s hand stressors and may result in the development of MSDs.

The standard grip that dentists use with their instruments, the same as gripping a pen to write, puts stress on the muscles of the thumb, pointer finger, and wrist. Instead, try placing the shaft of the instrument between your pointer and middle fingers and use your thumb as a guide, which will take the stress away from gripping the instrument and shift it to other muscles.

As a variation on holding your arms above the patient throughout the procedure, lightly rest your fingers on the patient’s teeth, using them as a fulcrum to move the instrument (intraoral), or rest your elbow on the side of the patient’s chair to take some weight off your shoulders and use your elbow as a fulcrum from which to work (extraoral).
Dentists/owners are responsible for providing a safe and healthful workplace for their workers. In the workplace, the number and severity of MSDs resulting from physical overexertion, and their associated costs, can be substantially reduced by applying ergonomic principles.

Implementing an ergonomic process is effective in reducing the risk of developing MSDs in high-risk industries as diverse as construction, food processing, firefighting, office jobs, healthcare, transportation, and warehousing. The following are important elements of an ergonomic process:

Provide Management Support - A strong commitment by management is critical to the overall success of an ergonomic process. Management should define clear goals and objectives for the ergonomic process, discuss them with their workers, assign responsibilities to designated staff members, and communicate clearly with the workforce.

Involve dental assistant/hygienist - A participatory ergonomic approach, where workers are directly involved in worksite assessments, solution development, and implementation is the essence of a successful ergonomic process.

Workers can:

Identify and provide important information about hazards in their workplaces. Assist in the ergonomic process by voicing their concerns and suggestions for reducing exposure to risk factors and by evaluating the changes made as a result of an ergonomic assessment.

Provide appropriate Training - Training is an important element in the ergonomic process. It ensures that workers are aware of ergonomics and its benefits, become informed about ergonomics related concerns in the workplace and understand the importance of reporting early symptoms of MSDs.

Identify early signs and symptoms - An important step in the ergonomic process is to identify and assess ergonomic problems in the workplace before they result in MSDs.

Encourage Early Reporting of MSD Symptoms - Early reporting can accelerate the job assessment and improvement process, helping to prevent or reduce the progression of symptoms, the development of serious injuries, and subsequent lost-time claims.

Implement Solutions to Control Hazards - There are many possible solutions that can be implemented to reduce, control or eliminate workplace MSDs.

Evaluate Progress - Established evaluation and corrective action procedures are required to periodically assess the effectiveness of the ergonomic process and to ensure its continuous improvement and long-term success. As an ergonomic process is first developing, assessments should include determining whether goals set for the ergonomic process have been met and determining the success of the implemented ergonomic solutions.

Begin to make some changes in the way you practice by incorporating some of these suggestions into your regular routine during the workday. You will find that you have less fatigue at the end of the day, you will experience less pain, and you will be able to provide the quality of service that you and your patients demand.

The second part of this article will address the various work practices that dentists perform, the risk factors, and suggestions to make them more hand friendly. Instrument use will be examined, and suggestions will be made to counteract the inherent dangers in using the instruments involved in dental work. Finally, recommendations for maintaining personal health, stress management techniques, as well as exercises and stretches will be covered to promote productivity and health over the life of your career.