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Oral health care providers and musculoskeletal disorders.

With musculoskeletal disorders representing more than 60 percent of occupational injuries in the dental field, the struggle towards musculoskeletal health continues to grow. (1) Although tactics to avoid musculoskeletal injuries in the dental professions are taught in educational programs, the injuries seem to still be occurring in many dentists, dental hygienists, dental technicians and dental assistants. These musculoskeletal disorders account for more than one-third of job absences among oral health care workers in the United States. (1)

There are many factors that contribute to dental care providers' propensity to musculoskeletal disorders. Prolonged awkward postures, repetitive movements, use of ultrasonic and rotary instruments, improper body mechanics, infrequent breaks and psychosocial factors can all cause musculoskeletal disorders, and those with occupations in the dental field are susceptible to all of them.

Musculoskeletal disorders are those that affect muscles, joints and bones of the human body, characterized by prolonged pain and limited mobility.' Examples of these disorders are (2)

* Arthritis (pain, swelling and stiffness associated with inflamed joints)

* Carpal tunnel syndrome (weakness, numbness or pain affecting the median nerve in the hand, thumb or ring finger)

* Degenerative joint disease (breakdown of the joints' smooth, lubricated surface)

* Epicondylitis (inflammation of the epicondyle in the humerus bone and surrounding tissues)

* Repetitive motion disorders (tissue damage associated with repeated trauma or movements)

* Tendonitis (deterioration of a tendon due to repetitive motion)

* Sciatica (compression of the sciatic nerve, causing pain to radiate into the buttocks and down the back of the leg from poor posture or muscle strain)

* Neck pain

* Back pain

Developing any of these disorders can lead to clinical incompetence and, if worsened, potential job loss.

Proper ergonomics is one of the first things taught in any dental education program. Without proper ergonomics, oral health care professionals may face a life of poor musculoskeletal health. The study of ergonomic interventions can help reduce the risks of developing any of the above musculoskeletal disorders.

Proper ergonomics in the dental setting includes neutral posture positioning, dynamic movement of the body and the use of as little force as possible. (3) A neutral, natural posture position is recommended. Neutral posture includes feet flat on the floor, back straight, knees at a 90-degree angle, head upright, elbows flexed at 90 degrees, shoulders relaxed, wrists straight and the forearm in mid-position with thumbs up. (3) Sitting in a neutral position, making sure that all of these positions are met, will reduce muscle strain in the neck, back, lower back and hands. Clinicians should never sit hunched over the patient; this can lead to rounded shoulders and musculoskeletal disorders.

Dynamic movement of the body is the second important ergonomic principle. Movement of the body decreases motionless forces created when clinicians hold their bodies in a single position for a long period of time. (3) By periodically moving and stretching the trunk of the body, muscle fatigue can be eliminated. Muscle fatigue occurs when the body is positioned one way for a period of time so that blood vessels are compressed and oxygen and energy supply to muscles are decreased. Muscle waste products accumulate, leading to pain and fatigue in the strained muscles. Periodically moving helps decrease muscle fatigue.

The last ergonomic principle involves the amount of force used clinically. Especially for dental hygienists, who sometimes have to use heavy force and repetitive motions, it is important to use as little force as possible. Maintaining a neutral position will help reduce the force necessary for practice. Additionally, dental hygienists should keep instruments sharp, use an ultrasonic scaler when possible and use ergonomically designed instruments. (3) Practicing proper ergonomics can reduce the chance of developing a musculoskeletal disorder.

Proper postural strategies in the operatory as well as stretching techniques can also help eliminate the development of musculoskeletal disorders. Working with the head forward and back hunched creates neck and back pain as well as headaches. The most efficient neck and shoulder posture is where the back is straight and the ears are directly over the shoulders. (4)

Two effective exercises that can be done chairside are the chin tuck and downward squeeze. During the chin tuck, the clinician sits tall with the tips of fingers together behind the lower neck, the arms and elbows relaxed. Keeping the eyes and chin parallel with one another, the chin is pulled up and backward and held for five counts. During the downward squeeze, the chin tuck is held throughout the exercise. The fingers are positioned pointed up and palms forward, then the shoulders are rolled back, squeezing the shoulder blades together and downward, held for one long breath and repeated five times. (4) Dentists, dental hygienists and dental assistants may not maintain perfect posture throughout the workday; therefore, it is very important to occasionally perform light stretches to relieve any muscle tightness.

Over the years, instruments have also evolved ergonomically in the dental field. From thin to thick, instruments have changed to better fit our hands and wrists. The variety in handle diameters has increased, and instruments have gotten lighter, so that less stress can be placed on the fingers and hands. To decrease the likelihood of developing musculoskeletal disorders, it is recommended that practitioners alternate between instruments with thin and thick handles. (5) Different muscles are worked when using instruments of different designs. Using instruments with varying designs varies muscle activity throughout the day. Using a padded mirror also helps reduce strain in the thumb muscles due to the pinch grasp clinicians use to retract the tongue and cheek. (5) Finally, textured handles provide clinicians with tactile signals during instrumentation. These handles increase the static friction between the object and the fingers, which decreases the amount of pinch force necessary. Textured handles create tactile signals at the end of finger movements, delivering a strong stimulus for the control of the finger muscles and allowing the clinician to grasp the instrument less forcefully. (5) Ergonomic instruments have helped clinicians reduce their chances of developing musculoskeletal disorders.

Many oral health care practitioners now use magnifying loupes to help maintain a neutral posture position. For dentists, dental hygienists, dental assistants and even dental technicians, looking inside the oral cavity or producing crowns and bridges can be stressful on the eyes and neck and require maintaining awkward positions over time. Loupes are designed specifically for the individual user. Lenses and prisms are created together that amplify an image without compromising the wearer's neck and back. (6) Studies have shown that clinicians who wear loupes sit with an upright posture and bend their necks less into unnatural positions. Forward flexion of the head and shoulder protraction also improve when wearing loupes. (6) The clinician's field of vision improves, decreasing the chance of poor posture. This leads to a decrease in the development of musculoskeletal disorders.

Even though a dental office may be equipped with ergonomically sound equipment, practitioners still bend their backs and twist their necks into awkward positions in order to see into the oral cavity. Mirrors are commonly used for indirect vision, but most dental care providers will say that nothing is better than direct vision, which sometimes entails awkward positions that put strain on muscles of the head, neck and upper and lower back. Achieving direct vision may cause unnatural postures that result in isometric muscle contractions. Static postures of the trapezius muscle have been noted as a specific problem in dental care workers in relation to neck and shoulder conditions. (7)

Different musculoskeletal disorders are found in different oral health occupations. In dentists, neck flexion, head rotation and the need for upper arm abduction are common postural risk factors for upper musculoskeletal disorders. Dentists often turn their necks to the left while bending their head to the right for direct vision. This act strengthens the muscles on one side of the neck while weakening the opposite muscles and can make it difficult to rotate the neck to the right while bending to the left. (7) In dental hygienists, upper extremity and neck disorders occurred more frequently than lower back injuries. Dental hygienists regularly flex the neck 30 degrees with side bending or rotating, as well as abducting the shoulders more than 45 degrees. These postures, combined with recurring movements, lead to fatigue of the trapezius muscles. (7) In dentists and dental hygienists, high levels of flexion and rotation of the neck, along with forward leaning posture, increase the chance of musculoskeletal disorders of the neck and shoulders.

Repetitive movements are a leading cause of musculoskeletal disorders in dental care providers. Dentists and dental hygienists perform the same procedures every day. Hygienists in particular often perform the same procedures on every patient throughout the day, which makes their job more repetitive than that of the dentist, assistant or technician. On average, a hygienist works seven to eight hours a day, treating patients every 45 to 60 minutes. These treatments may include scaling and root planing, regular prophylaxes or quadrant scaling. These procedures require concentrated hand and eye coordination and repetitive motions. (5) The dominant hand serves as the scaling hand, which holds many different instruments and moves in many directions. The non-dominant hand is used to hold the mirror for indirect vision and retraction of the tongue and cheek. This can reduce blood flow and oxygen transfer, which increases the risk of developing a musculoskeletal disorder.

Daily repetitive motions and postures such as flexing and extending of the wrists, tight grips and motionless stacking of the fingers and hands can also potentially lead to musculoskeletal disorders. (5) Repetitive movements performed daily can cause the development of musculoskeletal disorders. Whether it is a dentist repeatedly using a drill or a hygienist using repetitive motions while performing scaling and root planing, there is always the potential for musculoskeletal disorders.

In the dental field, one thing that cannot be avoided is the use of hand pieces, both rotary and ultrasonic. Dentists have to use a drill to perform most dental procedures, and hygienists use a low-speed hand piece to polish and ultrasonic scalers to break up tenacious calculus. Even dental technicians use vibratory hand pieces frequently throughout the day. High- and low-speed hand pieces, as well as ultrasonic hand pieces, produce vibrations that are harmful to the nerves of the shoulder, arm and hand. This leads to muscle strain and muscle fatigue, which further lead to pain. (1)

Vibrations created by hand pieces can lead to a combination of vascular, neurological and musculoskeletal disturbances, known in combination or individually as vibration syndrome. A vibration syndrome is associated with tingling and numbness of the hands as well as vasoconstriction of blood vessels, causing the fingers to appear white. After years of vibration exposure, fingers may appear swollen, painful and inflexible. (8) Vibrations in excess of 1 to 2 kHz are beyond what the human hand can feel through tactile sensitivity, so clinicians may not even be aware of them. Superficial tissues absorb the mechanical energy at high frequencies, which affects cutaneous mechanoreceptors located in the skin of the hand. Loss of sensitivity and motor accuracy performance can result, leading to accidents on the job such as dropping instruments and slipping of the fingers during procedures. (8) With periods of prolonged exposure to vibratory sensations, the motor skills of the hand may be compromised, tactile sensibility can decrease, and disturbances may occur in the regulation of grip forces. These symptoms are found most commonly in dentists and dental technicians who use vibratory tools for a long period of time throughout the workday. (8) Having to use vibratory and ultrasonic hand pieces is an occupational hazard that can lead to musculoskeletal disorders in dental care providers.

Even though proper operator and patient positioning is taught to all dental care providers, not all clinicians take advantage of it. This results in clinicians struggling to see into the oral cavity by twisting into awkward postural positions. Because the oral cavity is a small, narrow space, improper positioning of the operator and patient can put loads of stress on the operator. The first mistake most operators make is adjusting the patients before themselves. The first thing the operator should do is position him/herself comfortably in their chair, then position the patient. (9)

Commonly, clinicians also place the patient chair too high, so that their own shoulders elevate and arms abduct, leading to tension those muscles. Most clinicians also fail to adjust the headrest between treating maxillary and mandibular teeth, which leads to awkward static positions. Positioning of the dental light is also one of the most important adjustments that dental clinicians fail to address. Insufficient light can lead to headaches and eyestrain. Positioning the dental light correctly allows the clinician to see adequately without having to put strain on the head, neck and back muscles. (8) Every clinician is taught proper positioning, but in a clinical situation, time constraints and stress can cause clinicians to forget about what they have learned. Improper operator and patient positioning can eventually lead to musculoskeletal disorders.

Lack of frequent breaks causes tension that fatigues muscles throughout the day. Most successful workdays consist of eight to nine hours of work and one hour for a lunch break. This one-hour lunch break is not an adequate recovery time for the human body. For example, a dental hygienist's workday usually consists of seven to eight hours, normally treating a different patient every 45 to 60 minutes. One appointment is usually broken down into six to eight minutes of updating health histories, taking radiographs and periodontal charting. Five to seven minutes are dedicated to patient education; 25 to 35 minutes are spent treating the patient, four to five minutes are spent polishing and flossing, and four to five minutes are used to clean the room. (5)

During the course of the day, routine periodontal scaling/root planing procedures may be performed on patients with periodontal disease. Forty-five to 60 minutes are spent scaling each quadrant, or 90 to 120 minutes spent on cleaning two quadrants. In this time, the dental hygienist must use intense hand and eye coordination, muscles, static posture and repetitive motions to successfully treat the patient. (5) If dental care providers must take all this time to treat patients and are given only one hour break time, how can the body truly relax and recover? A few minutes between patients are not enough to allow muscles, tendons and bones to heal from tension that was put on them throughout the appointment. Inadequate break time does not allow for recovery and so contributes to the development of musculoskeletal disorders.

Also contributing to musculoskeletal disorders are psychosocial factors. These include work-related issues such as organization of the job, number of hours worked and patients seen, support amongst coworkers, job control and style of supervision, as well as conflicts at home. (7) Studies have shown that since dental assistants and hygienists are predominantly female, they may be greatly affected by work and family conflicts. (7) Having the stress of seeing patients one after the other, repeating similar procedures, handling work relations, juggling family and work issues and dealing with stubborn patients have been associated with tension of the neck and shoulders as well as musculoskeletal disorders of these regions. (7)

Proper ergonomics, postural positioning and stretching strategies, ergonomic instruments and magnifying loupes can prevent musculoskeletal disorders, but not every clinician in the dental field practices using all of them, as musculoskeletal disorders still represent more than 60 percent of occupational injuries in the dental field. (1) Although clinicians are educated to avoid occupational hazards, the daily work environment does not always make it easy to practice safely. The more that practitioners adhere to known methods of avoiding musculoskeletal injury, the better their chances of enjoying a long and healthy career.


(1.) Kreismann J. The struggle for musculoskeletal health. Dimensions of Dental Hygiene. 2007; 5(9): 24-5.

(2.) Wei N. What causes musculoskeletal disorder. Arthritis-treatment-and relief. 2004. Available at: Accessed Dec. 5, 2011.

(3.) Sanders MJ, Turcotte C. Posture makes perfect. Dimensions of Dental Hygiene. 2011; 9(11): 30-2, 35.

(4.) Valachi B. Improving your musculoskeletal health: postural, positioning, and stretching strategies for career longevity. Dimensions of Dental Hygiene. 2003; 1(3): 20-2, 24, 26.

(5.) Simmer-Beck M, Branson BG. An evidence-based review of ergonomic features of dental hygiene instruments. WORK. 2008; 35(4): 478, 480, 484.

(6.) Branson BG, Black MA, Simmer-Beck M. Change in posture: A case study of a dental hygienist's use of magnification loupes. WORK. 2008; 35(4): 468, 474.

(7.) Morse T, Bruneau H, Dussetschleger J. Musculoskeletal disorders of the neck and shoulder in the dental professions. J Dent Hyg. 2009; 35(4): 424-5.

(8.) Brune DK, Edling C. Occupational hazards in the health professions. Boca Raton, Fla.: CRC Press, 1989.

(9.) Brame JL. Seating, positioning, and lighting. Dimensions of Dental Hygiene. 2008; 6(9): 36-7.

By Tara Ghanbarian, RDH, BSDH

Tara Ghanbarian, RDH, BSDH, graduated in May 2013 from the Dental Hygiene Bachelor of Science Degree Program at Farmingdale State College. She currently works part time in two dental offices in Long Island, N.Y., while pursuing her dream of going to dental school. She wishes to one day have a great impact on both the dental and dental hygiene fields.
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Title Annotation:strive
Author:Ghanbarian, Tara
Article Type:Report
Geographic Code:1USA
Date:Aug 1, 2013
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