Musculoskeletal Disorders (MSD’s) are disorders of the muscles, tendons, peripheral nerves or vascular system not directly resulting from an acute or instantaneous event (e.g, slips or falls). Dental professionals often develop musculoskeletal problems, which are related to sub-optimal work-environment ergonomics that might be responsible for improper sitting postures and movements causing unnecessary musculoskeletal loading, discomfort, and fatigue. This review article introduces some of the key concepts and practical aspects of musculoskeletal disorders in dental personal.

•    Dentist
•    Musculoskeletal disorders
•    Work related disorders
•    Dental ergonomics 

Dental professionals often develop musculoskeletal problems, which are related to sub-optimal work-environment ergonomics that might be responsible for improper sitting postures and movements causing unnecessary musculoskeletal loading, discomfort, and fatigue [1,2].

The World Health Organization defines an MSD as “a disorder of the muscles, tendons, peripheral nerves or vascular system not directly resulting from an acute or instantaneous event (e.g., slips or falls). These disorders are considered to be work-related when the work environment and the performance of work contribute significantly, but are only one of a number of factors contributing to the causation of a multi factorial disease [3].”

Insufficient or inappropriate equipment, inappropriate workarea design, direct injuries, repetitive movements from working with dental instruments, or sitting for extended times with a flexed and twisted back are contributing factors to neck and lowback ailments [4].

Musculoskeletal problems happening outside the work environment can either worsen with work or make work difficult. Various structures can be affected-muscles, ligaments, tendons, nerves, joints, and supporting structures (intervertebral discs). A number of disorders are included under this category: upper and lower back pain, herniated disc, neck pain with or without cervical root problems, carpal tunnel syndrome, tendinopathies, shoulder pain, rotator cuff tendinopathies, and repetitive strain injuries. It has been reported that young and less experienced dentists experience more musculoskeletal disorders compared to older and experienced one [5].

Possible explanations were that experienced dentists are probably better at adjusting their working position and techniques in order to avoid musculoskeletal problems, when compared to their less experienced counterparts, or that they simply developed coping strategies to help deal with the pain. A more likely explanation; however, is simply that those dentists with severe musculoskeletal problems would have ceased working, and would thus not have been captured in a crosssectional survey of dentists.

Mechanism of musculoskeletal disorder [6,7]

Dentists frequently assume static postures, which require more than 50 percent of the body’s muscles to contract to hold the body motionless while resisting gravity. When the human body is subjected repeatedly too prolonged static postures, it can initiate a series of events that may result in pain, injury or a career-ending MSD. Muscle imbalances, ischemia, trigger points, joint hypomobility and spinal disk degeneration are some of the physiological consequences of Prolonged Static Postures (PSPs). The mechanism of musculoskeletal disorder can be explained by means of flowchartDentists must understand the mechanisms that contribute to MSDs so they can make informed choices regarding ergonomic equipment, exercise and lifestyle. Having this knowledge is key in preventing and managing work-related musculoskeletal problems in clinical dentistry

Classification of musculoskeletal disorders [1,8]

According to Rundcrantz BL (1991) musculoskeletal disorders among dental practitioners can be classified as- Table 1.

Chopra A (2014) Musculoskeletal Disorders in Dentistry- A Review. JSM Dent 2(3): 1032.

Musculoskeletal problems can be managed or alleviated effectively using a multifaceted approach that includes–

1. Postural Awareness Techniques

2. Positioning Strategies

3. Periodic Breaks and Stretching

4. Strengthening Exercises

5. Education

Postural Awareness Techniques

These includes.

Maintain the low back curve: Maintaining the low back curve when sitting can reduce or prevent low back pain [9,10]. The following practices can help maintain the low back curve

1. Tilt the seat angle slightly forward five to 15 degrees to increase the low back curve.

2. Sit close to the patient and position knees under the patient’s chair if possible. This can be facilitated by tilting the seat and using patient chairs that have thin upper backs and headrests.

3. Consider using a saddle-style operator stool that promotes the natural low back curve by increasing the hip angle to approximately 130 degrees.

4. Adjust the chair so your hips are slightly higher than your knees and distribute your weight evenly by placing your feet firmly on the floor.

5. Use the lumbar support of the chair as much as possible by adjusting the lumbar support forward to contact your back.

6. Stabilize the low back curve by contracting the transverse abdominal muscles.

7. Pivot forward from your hips, not your waist [11].

Use magnification: Proper selection, adjustment and use of magnification systems have been associated with decreased neck and low back pain, as they allow operators to maintain healthier postures [12].

Adjust operator chair properly: Operators need to know how to adjust the features of their chairs to obtain maximal ergonomic benefits which includes

1. Adjust your chair first then adjusting patient chairs to accommodate the patients. Allowances can be made when working with patients who are elderly or disabled.

2. Position the buttocks snugly against the back of the chair.

3. Place feet flat on the floor and adjust the seat height up until thighs gently slope downward while the feet remain flat on floor.

4. Move backrest up or down until the lumbar support nestles in the natural lumbar curve of the low back. Then angle the lumbar support forward to facilitate contact with the low back.

5. Tilt the seat forward about five to 15 degrees.

6. Adjust armrests, which are designed to decrease neck and shoulder fatigue and strain, to support elbows in the neutral shoulder position [11].

Positioning strategies

The various positioning strategies includes

Avoid static postures: workers should vary their work positions as often as possible to shift the workload from one group of muscles to another [10,13].

Alternate between standing and sitting: Standing uses different muscle groups than does sitting; therefore, alternating between the two positions let one group of muscles rest, while the workload is shifted to another group of muscles. Alternating between standing and sitting also can be an effective tool in preventing injuries [14].

Reposition the feet: Subtle changes in foot position can shift the workload from one group of low back muscles to another, allowing the overworked tissues to be replenished with nutrients.

Position patients at the proper height: Operators should take the time to position their patients properly for mandibular and maxillary procedures. Generally, patients should be placed in a semi supine position for mandibular procedures and a supine position for maxillary procedures [11].

Avoid twisting: When possible, dentists should position instruments within easy reach. Operators should try to retrieve items with the closest hand, especially with rear delivery systems, to avoid twisting or reaching across the body. Repeated unilateral twisting in one direction may result in muscle imbalances or structural tissue damage, leading to low back pain [15].

Periodic breaks and stretching

Chair side directional stretching: Stretches performed in the reverse direction of awkward PSPs may prevent muscle imbalances that can lead to pain and MSDs. Directional stretches can be performed in or out of the operatory and can be incorporated into a daily routine that facilitates balanced musculoskeletal health. Directional stretching involves a rotation, side bending or extension component that generally is in the opposite direction of that in which the operator frequently works.

Frequent stretching breaks address the detrimental physiological changes that can develop while working in optimal or awkward PSPs: ischemia, trigger points, muscle imbalances, joint hypomobility, nerve compression and disk degeneration. Furthermore, stretching increases blood flow to muscles; increases production of joint synovial fluid; reduces formation of trigger points; maintains normal joint range of motion; increases nutrient supply to vertebral disks; creates a relaxation response in the central nervous system; warms up the muscle before beginning to work; identifies tight structures that may be predisposed to injury [11].

Treating Trigger points: Sometimes, operators may experience pain that is not relieved with stretching but instead worsened by it. This pain may be caused by a sustained contraction inside a tight band of muscle known as a trigger point, which feels like a small hard knot. When firm pressure is applied, trigger points are painful and may refer pain to another area. They do not allow the muscle fibers to contract or relax; therefore, they effectively decrease flexibility and reduce blood flow to the muscle. It is important that operators release trigger points as soon as possible.

Various people can help treat trigger points:

1. Physical therapist trained in trigger point therapy, contract

5. The dentist self-administering trigger point therapy using a tennis ball or other small ball between the back and a wall or using a trigger point self-massage tool.

MSDs  in dentistry often begin with fatigue of the postural stabilizing muscles of the trunk and shoulders. As these muscles fatigue, operators tend to slump into poor posture, setting the stage for injuries. Dentists should perform specific strengthening exercises for the trunk and shoulder girdle to enhance the health and integrity of the spinal column, maintain good overworking posture, optimize the function of the arms and hands and prevent injuries. Aerobic exercise Aerobic exercise should be performed three to four times a week for at least 20 minutes. One major contributing factor to MSDs is decreased flow of nutrients and oxygen to muscles. Aerobic exercise increases blood flow to all of the tissues in the body and improves their ability to use oxygen. In addition, aerobic exercise improves cardiovascular and cardiorespiratory function lowers heart rate and blood pressure, increases high-density lipoprotein (good) cholesterol, decreases blood triglycerides, reduces body fat, improves stress tolerance, increases mental acuity improves sleep quality and may increase longevity. Operators should choose aerobic exercises that they enjoy.

Stress management

Stress can elicit muscular contraction and pain, especially in the trapezius muscle. Operators may use various stress-reduction techniques to decrease stress-related muscular tension. They include breathing techniques, progressive relaxation, visualization, massage, aerobic exercise, meditation or yoga [16].

Education

To protect their own health, dentists should seek out and receive education about musculoskeletal health, injury prevention and dental ergonomics. Ideally, this education should begin during dental school and continue through the dentist’s professional life.

Dental operators can be taught to manage and prevent injuries effectively. They can educate themselves and their staff members using a multifactorial approach that includes preventive education, postural and positioning strategies, proper selection and use of ergonomic equipment, and frequent breaks with stretching and strengthening techniques before painful episodes occur. Prevention strategies should be easy to use to ensure long-term compliance [11,17,18].

Overall, this review clearly demonstrates that MSD represent a significant burden for the dental profession. Adopting adequate postures in clinical practice and having a favorable work environment could reduce the MSD’s. Therefore, it is of vital importance to promote the occupational health and prevention programs regarding ergonomic postures which must be acquired by the dentists during their clinical practices

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