Cruisin' - Part 2

Dental Procedures have been described with 5 classes of motion by Betty Finkbeiner in her work with 4-handed Dentistry.

Class I – fingers only such as flipping ends of the instrument
Class II – fingers and wrist – transferring an instrument
Class III – fingers, wrist and elbow – oral evacuation and reaching for a handpiece
Class IV – the movement of the entire arm and shoulder – reaching for supplies, mixing of dental materials
Class V – movement of the whole torso – adjusting the light

Ergonomically, movement should be limited to class 1, 2, and 3 with avoidance of class 4 and 5 if possible.

The work area around the patient is arranged into zones representing
hours on a clock. The activity zone for the operator is 7 o'clock to 12 o'clock. All activities of the operator at the chairside are performed in this zone. The assisting zone is from 2 o'clock to 4 o'clock. In this zone, the assistant is positioned. The assistant transfers materials and instruments in the transfer zone, which is from 4 o'clock to 7 o'clock (Bird & Robinson, 2005).

Ergonomically, the design of the work area is a 20-inch radius. Keep frequently used items such as an air-water syringe, high volume evacuator, and saliva ejector within easy reach. All equipment and instruments should be within maximum vertical and horizontal reach. This is the sweep of your forearm in a reach of the vertical and horizontal direction. Front delivery systems are best. Avoid rear delivery systems because they require twisting of the body. You should keep everything approximately waist high, not above shoulder level or below the waist. Those levels require twisting, turning of your back and shoulders. If a side delivery system is utilized, make it your dominant side. Again, this will require less overextending of your arm and shoulder (Bird & Robinson, 2005).

Do not overlook patient positioning. The position of the patient can significantly affect your posture. When reclining the patient, place his or her head in the same plane as their feet. Many dental practitioners try to perform procedures with the patient in an upright position. This causes practitioners to compensate by twisting their neck and back to see. Do not be afraid to ask patients to turn their heads or tilt their chins up or down. Patients are willing to comply if asked. This will allow better access and vision in the oral cavity. Try using indirect vision for those hard to access areas such as buccal of the left side of the mouth and lingual of the right side.

Now that you know the basics let me discuss specifics. The use of optical loupes can assist vision while maintaining proper posture. Loupes allow your back to remain straight with less bending forward to see correctly. When considering the purchase of loupes, there are several facts to consider other than cost. There are two types of loupes: Through-the-lens are fixed on the lens of the glasses. Flip-up devices are movable. There are advantages and disadvantages to both types, so the selection is the preference of the clinician.

One of the most overlooked ergonomic items used every day is gloves. Most offices use ambidextrous gloves. These gloves are not hand specific but can be worn on either left or right hand. Ambidextrous gloves place the thumb in the same plane as the fingers. This causes strain on the thumb, which can cause your hand to ache. Hand-specific gloves allow the thumb to be in a more natural position. Another consideration is the size of the glove. Since there is no standardization of glove sizes, sizes vary drastically from one manufacturer to another. When deciding on a proper glove size, make sure the glove is not too tight across the palm or too constricting at the wrist. Also, the finger length should be adequate to allow for comfortable finger movement (Guignon, 2003).
What about instruments, handpieces and other equipment? How are they involved in ergonomics? Handpieces and air/water syringes have hoses that are coiled and can be heavy. Their coiled cord places resistance against the wrist and hand. If the cord is long enough, put it in your lap, so the excess is not dangling down. Swiveling devices can be placed on a handpiece reducing handpiece torque. Newer handpieces are much lighter than older models. If your air/water syringe has a tightly coiled cord, consider replacing it with a lightweight hose (Guignon, 2003).
Instruments are another consideration. When using instruments, choose the proper one for the task at hand and use it the correct way. Instruments with large, hollow, and textured handles require less gripping force; thus, they are easier on the fingers and wrist. Choose instruments designed with well-balanced weight. You should keep the instruments sharp. This includes hatchets and chisels, not just scalers (Rethman, 2003).

Scheduling of procedures should be considered as well. If all your difficult procedures are scheduled back-to-back, it doesn't allow your body any relaxation time. You want your day to be productive, but not backbreaking. Try to place easier procedures such as sealants or impressions between crown preparations or long restorative procedures. This will allow your body some relaxation during the day.
Climate control of the workplace is essential too. Exposure to cold air or drafts can cause muscles to constrict, leading to fatigue or overworking of the muscles. This affects the muscles of the neck, shoulders, and back in particular. Always wash your hands in warm water to decrease hand fatigue.

Regular stretching exercises for your neck, shoulders, back, arms, and fingers can prevent some work-related injuries and relax the body. Stretching should be performed every hour and slowly while exhaling into the stretch. Some exercises are described in the sidebar above (Michalek-Turcotte & Atwood-Sanders, 2000). All of these exercises can be performed in between patients, after updating the medical history or while preparing the operatory for the next patient.
If we remember to utilize ergonomics in the workplace, we can have a long and pain-free professional career.

The primary risk factors for WMSD's, in general, are Repetition, Force, Mechanical Stresses, Posture, Vibration, Extrinsic Stresses and Temperature and all except temperature are factors in the dental profession. As you know, risk factors do not necessarily equate with injury - increased awareness of the risks can help prevent injury if adjustments are made to the tasks and environment.

Typical Dental Office Risks:

Low Back Pain – Sciatica, Disk and Vertebral Problems

Upper Back Pain

Neck Pain – Disc and Vertebral problems

Shoulder Pain – Impingement syndrome, Rotator Cuff Tendonitis

Hand, Wrist, Elbow Pain – Ulnar Nerve Problems, Lateral and Medial Epicondylitis, Carpal Tunnel, DeQuervains, Trigger Finger, Arthritic Joint Changes

This has resulted in a high number of dental care workers being forced into early retirement due to the prevalence of injury and disability.

Many dental equipment/supply companies have advertised "Ergonomic" equipment, which has caused confusion among dental professionals as to how to chose the truly ergonomically correct design and equipment for their specific needs.

References
(1.) Pollack RD. Ergonomics: Comfort by design. Dental Teamwork 1989; Sept/Oct: 163-66.
(2.) Hodges K. Concepts in nonsurgical periodontal therapy. Albany, NY: Delmar Publishers; 1998.

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