Prevention
Injury Prevention for the Practice of Dentistry
Adam J. Yoser, DC; and Ronald S. Mito, DDS
Copyright 2002 Journal of the California Dental Association.
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There is an abundance of dental professionals with work-related pain and dysfunction. Dentistry poses a huge challenge because of the ergonomics of dental work The biggest risk factors are the awkward prolonged seated postures with no back support and the limited range of motion and isometric muscle contraction created by working in a confined area, namely the mouth. The following manuscripts offers exercises that constitute a preventive program to target the typical problem areas of the dental professional -- the neck, lower back and wrist/hand.
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Using a sports medicine approach, dentistry may be viewed as a profession much like a "sport." There is an abundance of dental professionals with work-related pain and dysfunction. Dentistry poses a huge challenge because of the ergonomics of dental work The biggest risk factors are the awkward prolonged seated postures with no back support and the limited range of motion and isometric muscle contraction created by working in a confined area, namely the mouth. The physiologic effects of these elements are patterns of muscle imbalance and neuromuscular inhibition causing dysfunction and/or pain. Advances in ergonomics continue to ease the physical challenges of the dental profession. Use of office ergonomics does not replace the basics of a body being physically conditioned, however. One must try to learn how to work around the various risk factors. The ultimate goal should be to prevent injuries and maintain the health of the dental team by following a tailored program of rehabilitative exercises.
Nature of the Problem
Clearly, the practice of dentistry does not result in the contact injuries of football or hockey. Instead, the root causes of pain are cumulative microtrauma and dysfunction from repetitive overuse in awkward positions.
Microtrauma involves very minor bodily insults that repair with scar tissue that is less elastic than the unscarred tissue. Repetitive microtrauma can also be responsible for degenerative arthritic changes in the spine. This causes the individual to gradually experience almost imperceptible decreasing function, range of motion, elasticity of tissue, and, consequently, strength. Compensatory patterns of movement and muscle use develop, and the body becomes less efficient and prone to pain.
Muscle Imbalance
Dental postures create prolonged, repeated muscle contraction, which promotes a pattern of muscle imbalance typical of dental professionals. Muscle physiology is such that humans are designed with agonist and antagonist muscles. For a person to move a limb, two deliberate neurologic messages are sent. One is for the muscle to contract. The other is for the opposite, or antagonist, muscle to relax. Without the second message, movement at a joint cannot occur. Consequently, repetitive patterns of muscle use and contraction deliberately send a message of relaxation and disuse to specific muscle groups. This is how patterns of weakness and disuse develop.1 Knowing the typical patterns of muscle use in dentistry is necessary to design preventive exercise routines.
Isometric Muscle Contraction
The human neuromuscular system is wired for movement and range of motion. Maintained positions rapidly produce fatigue and pain as the body senses the static insult. The static contraction of muscle decreases circulation thereby affecting the nutrition to tissues. Consequently, normal elimination of muscle waste products and dispersion of fluids are interrupted.2 This is viewed in Eastern medicine as tissue stagnation and unbalanced flow of energy leading to pain. The further theory is that whichever energy pathways (meridians) are involved will cause related general health problems. Proper stretching and neuromuscular control can help counterbalance an eight-hour workday of confined, repeated positions.
Risk Factors and Prevention Tips
Prolonged Awkward Postures
Forward flexed postures put extreme compression on the lumbar spine and discs. One should not sit nor stand in a prolonged position with the upper body twisted relative to the pelvis. Both feet should be supported on the floor. In addition, sitting on a thick wallet can shift the pelvis.
Excess Head Tilt/Rotation
Tilting the head to one side and rotating it diminishes the size of the inter-vertebral foramen where the nerve in the neck goes down to the hands. One should avoid extreme positions and stretch the opposite way after each procedure. Maintaining a postural sense of elongation lifting from the sternum will help keep good upper body posture. Prolonged positions with the elbows held up and out transmit a lot of tension to the shoulder girdles. One should not lift the shoulders up toward the ears and should avoid extreme neck positions.
Standing vs. Sitting/Static Load
Studies indicate that sitting creates significant increased lumbar disc pressure relative to standing. When one is standing, the disc pressure is about 35 percent of the pressure in the relaxed sitting position. Forward flexion, as in typical dental postures, is a further increase in disc pressure.3 The number of hours sitting requires regular breaks. Use of specific stretches allows one to break the static load and overuse patterns. One should to try to incorporate standing during dental procedures.
Patient Positioning
Correct use of pillows or magnification is sometimes needed to obtain the proper focal length. A person strains to see with his or her entire body as well as the eyes. The patient should be repositioned to attain an appropriate focal length and good postural position.
Use of Mirror/Eyesight
The body strains for correct vision. It is recommended that one refocus one’s eyes on a distant point at least 20 feet away after sustained concentration. This helps maintain good vision and accommodation.
Grip/Force
Excessive force while gripping dental instruments creates overuse of hand and forearm muscles. One should do warm-up stretches of the wrist and hands and avoid extreme angles during work. A person who is suffering wrist and/or hand symptoms may be sleeping with his or her hands curled in extreme angles. Use of a wrist brace while sleeping may be recommended.
General Principles for the Preventive Exercise Routines
While there are training aides and specialized equipment, the intent of this article is to provide a simplistic approach to prevention. Stomach crunches and sit-ups are essential exercises but are too basic to be illustrated here.
The following exercises constitute a preventive program to target the typical problem areas of the dental professional -- the neck, lower back and wrist/hand. The exercises should be performed to the point of discomfort, but not to the point of pain. A person who is already sore should take a hot shower or apply a medicated balm that "warms up" the muscles before starting the program. Some of these exercises are meant to activate supportive muscles, while others are more of a muscular stretch. Therefore, a stretching sensation will not be felt with each exercise. The exercise routines are in a helpful numbered sequence but the order can be varied if desired.4 For the exercises to be most effective, one should:
* Try to do the routine twice a day;
* Hold each stretch for a few breaths; and
* Alternate left and right sides between repetitions.
The Exercise Routines
Neck/Upper Body
Figures 1 through 8.
Lower Body
Figures 9 through 16.
Wrist/Hand
Figures 17 through 18.
Summary
Dentistry can inherently be physically stressful. To offset this tendency, the dentist should correct his or her posture and work with the ergonomics of how the dental team functions together. The crucial preventive step is to athletically prepare one’s body. After all, the real toll of neck and back pain goes beyond productivity and the longevity of a career. One’s physical well-being affects the general efficiency and pleasure of practicing dentistry as well as the quality of life outside the office.
Finally, from the Earl of Darby (1799-1869) comes this last bit of inspiration: "Those who do not find time for exercise, sooner or later will have to find time for illness."
Authors
Adam J. Yoser, DC, practices chiropractic sports medicine in Brentwood, Calif. As the co-founder of Pacific SportsMedicine Alliance, he has served as medical director for the U.S. Professional Surf Tour and the American Jiu-jitsu Association. He has lectured on injury prevention at the University of California at Los Angeles School of Dentistry and various dental symposiums in Southern California.
Ronald S. Mito, DDS, FDS, RCS(Ed), is a professor and associate dean for clinical dental sciences at the University of California at Los Angeles School of Dentistry. He is also a member of the CDA Board of Trustees and a member of the ADA Council on Government Affairs.
References
1. Prentice W, Rehabilitation Techniques in Sports Medicine. Mosby, St. Louis, 1994, pp 164-7.
2. Donkin S, Sitting on the Job. Houghton Mifflin, Boston, 1989, pp 95, 216.
3. Nachmenson A, Intravital dynamic pressure measurements in lumbar discs. Scand J Rehab Med, R Suppl 1, 1970.
4. Yoser A, Prevention and management of occupational neck and back pain. Healthwatch Home Study LLC, Woodland Hills, Calif, 1998.
To request a printed copy of this article, please contact/Adam J. Yoser, DC, 13050 San Vicente Blvd., #206, Los Angeles, CA 90049 or at DrYoser@aol.com.
Table 1. Risk Factors
1. Prolonged Awkward Postures
2. Excess Head Tilt/Rotation
3. Standing vs. Sitting
4. Patient Positioning
5. Use of Mirror/Eyesight
6. Grip/Force
Figure 1. Rhomboids, deltoids. Grasp the right elbow with your left hand, twist the upper body to the left, and pull the right arm across the body. Repeat three to five times on each side.
Figure 2. Latissimus dorsi, intercostals, shoulder girdle. Reach diagonally forward with the left arm as the right hand further pulls the left arm at the wrist. Keep pulling the arm forward as you shift your body weight backward. Repeat three to five times on each side.
Figure 3. Pectoralis, biceps. Stand about 1 foot from the wall and place your right hand with an open palm against the wall. Bend the right knee as you lean forward, stretching your chest and arm. Vary the height of your hand against the wall to stretch different muscles. Repeat three to five times on each side.
Figures 4a and b. Midback muscles (trapezius, rhomboid, posterior deltoid), rotator cuff. Start with the arms outreached, overhead (Figure 4a) and slowly draw a semicircle backward (Figure 4b). Use midback muscle strength, not a stretch, to perform this exercise. Repeat 15 to 30 times.
Figure 5. Extensors (trapezius, paraspinals). Push down with both hands as you lift up from your sternum and slowly look behind you. Repeat three to five times.
Figures 6a and b. Extensors and intersegmental musculature. Support the back of your head with both hands (Figure 6a). Look straight ahead as you allow your chin to come forward. Using moderate resistance, pull your head back as you tuck your chin (Figure 6b). Note: Keep eyes focused straight ahead for this exercise. Repeat five to 10 times.
Figure 7. Scapular stabilizers and shoulder extensors. Squeeze shoulder blades together as you bring both elbows all the way behind you. Repeat 15 to 30 times.
Figure 8. Trapezius, levator scapulae. Bring your left arm behind your back. Turn your head to the right and gently pull the head forward with your right hand. Repeat three to five times on each side.
Figure 9. Gluteals, spinal rotators. Start flat on your back with both arms outstretched. Cross your left knee toward the right shoulder. Use your right hand to help pull the left knee across your body. Repeat three to five times on each side.
Figure 10. Gluteals, hip rotators. Lie on your back with knees bent and feet on the ground. Cross the left ankle over the right knee. Use both hands to pull the right thigh toward your chest. Repeat two to three times on each side.
Figures 11a and b. Trunk musculature, intersegmentals. Lie on your back with knees bent and feet on the ground, about hip distance apart (Figure 11a). Gently push your tailbone into the ground as you wiggle your hips, as if you are scratching your back (Figure 11b). Progressively move the scratching from the lower back up toward your neck. Allow enough time at each vertebral level to warm up your back muscles and create spinal movement.
Figures 12a and b. Spinal extensors, flexors. Kneel on all fours. Allow your head to look up and your back to arch (Figure 12a). Move into the opposite movement as you round your back, tilt your pelvis and try to look into your belly button (Figure 12b). Alternate from 12a to 12b five to 10 times.
Figure 13. Iliopsoas, hip adductors. Kneel on the left knee. Look upward as you stretch your body to the right, stretching your left groin. Repeat three to five times on each side.
Figure 14. Spinal extensors. Lie on your stomach with hands placed down at shoulder level. Keep hips to the ground as you extend the upper body upward. Use your back muscles; do not push up forcefully with arms. Repeat three to five times.
Figure 15. Extensors, trunk stabilizers. Start by kneeling on all fours. Simultaneously lift the right arm and the left leg parallel to the ground. Maintain your spine in an elongated straight line. Return slowly to starting position. Repeat 10 to 30 times on each side.
Figure 16. Gluteals, quadratus lumborum. Place your right hand on the wall and place the right foot on edge behind the left foot. Push your right hip toward the wall as you bring your head away from the wall. Note: Vary the placement of the back foot to your comfort level. Repeat three to five times on each side.
Figure 17. Deep soft tissues of the wrist. Keeping your left arm straight, grasp your left wrist firmly. Traction your wrist as you pull outward with your right hand. Repeat three to five times on each side.
Figures 18a and b. Forearm flexors, deep soft tissues of the wrist. Place both hand on the wall with fingers pointing upward. Lean your body weight forward to create a stretch at the forearms and wrist (Figure 18a). Vary the height of the placement of your hands on the wall to change the stretch. Try this exercise with the fingers pointing downward (Figure 18b). Repeat three to five times.
