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 Table of Contents  
REVIEW ARTICLE
Year : 2022  |  Volume : 16  |  Issue : 1  |  Page : 72-76

Musculoskeletal disorders in dentists and relearning the ergonomics


1 Military Dental Centre, Gwalior, Madhya Pradesh, India
2 Department Army Dental Centre (R & R), Delhi Cantonment, New Delhi, India

Date of Submission05-Apr-2021
Date of Acceptance20-Dec-2021
Date of Web Publication05-Apr-2022

Correspondence Address:
Omprakash Dulhani
BDS Department Military Dental Centre, Gwalior, Madhya Pradesh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jodd.jodd_15_21

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  Abstract 


Musculoskeletal disorders (MSDs) are one of the most common occupational diseases. It can cause pain and dysfunction of routine functioning of back/neck/limbs. MSDs can amount to loss of working period, increased labor costs, and human injuries. Unhealthy postures while working are the cause of MSDs among dentists. Ergonomics is an applied science concerned with improving productivity and safety and not just preventing work-related MSDs. Ergonomics ensure optimal working conditions along with physical and psychological comfort throughout the execution of the clinical acts.

Keywords: Ergonomics, exercises, musculoskeletal disorders


How to cite this article:
Dulhani O, Mukherjee M. Musculoskeletal disorders in dentists and relearning the ergonomics. J Dent Def Sect. 2022;16:72-6

How to cite this URL:
Dulhani O, Mukherjee M. Musculoskeletal disorders in dentists and relearning the ergonomics. J Dent Def Sect. [serial online] 2022 [cited 2022 Nov 29];16:72-6. Available from: http://www.journaldds.org/text.asp?2022/16/1/72/342637




  Introduction Top


Musculoskeletal disorders (MSDs) can cause pain, weakness, paresthesia, muscle ischemia, imbalances, necrosis, and reduced range of joint mobility, spinal disk herniation, or degeneration.[1] MSDs have an impact, not only on the physical but also on the psychological and social aspects of the practitioners. MSDs in severe cases result in frequent absences and early retirement.[2]

Ergonomics is an applied science concerning with the customization of workstations, equipment, and work methods to fit specific individuals and not the other way.

Various studies have revealed that more than half the sample size suffered from some painful sites and females suffered more compared to males.[3],[4],[5]


  Pain Assessment Scales Top


Musculoskeletal complaints are firstly recorded by either Nordic Musculoskeletal Questionnaire (NMDQ) or Cornell Musculoskeletal Questionnaire (CMDQ). NMDQ acquires information pertaining to pain/discomfort in nine anatomical regions from neck to feet. CMDQ combines the pain with work-related impairments for twenty body regions. Subsequently, postural analysis is done to assess which abnormal/deviated postures are responsible for these musculoskeletal symptoms. Postural analysis is one of the most relevant techniques to analyze work activities, from the view of ergonomics. Postural analysis employs methods such as OWAS, QEC, RULA, REBA, OCRA, ROSA, SI (Software ergonomics), ACGIH TLV, NIOSH lifting equation, and ISO 1128-3.[6]

[TAG:2]Classification of Musculoskeletal Disorder[7][/TAG:2]

Musculoskeletal disorders can broadly be classified as

Neck and shoulder disorders

  1. Myofascial pain disorder
  2. Cervical spondylosis
  3. Thoracic outlet syndrome
  4. Rotator cuff tendinitis/tears.


Hand and wrist disorders

  1. De Quervain's disease
  2. Carpal tunnel syndrome
  3. Guyon's syndrome
  4. Trigger finger
  5. Tendinitis/Tenosynovitis.


Back disorders

  1. Herniated spinal disc
  2. Lower back pain
  3. Sciatica.



  Risk Factors for Musculoskeletal Disorders Top


  • Biomechanical
  • Ergonomic
  • Psychological
  • Work factors
  • General health and comorbidities
  • Genetic predisposition.



  Mechanisms Leading to Musculoskeletal Disorders Top


Neck and shoulder disorders

To perform high finesse dental procedures, dentists have to gain access, visibility, and control in the patient's mouth, leading to protruding and holding the head and neck in an unbalanced forward posture for longer durations. This leads to frequent and prolonged contraction of muscles of cervical and upper thoracic spine. This cycle leads to the development of various neck and shoulder symptoms. Therefore, stretching of neck muscles, strengthening of the deep postural cervical muscles, and preservation of the cervical lordosis in correct posture are significant.

Hand and wrist disorders

The causative factor for hand and wrist disorders is the chronic regular flexion and extension movements of wrist and digits, especially in the pinch position, also grasping the sharp instruments handles for extended durations leads to hand and wrist disorders. It must be noted that instrument handles have not to be very thin, the instruments have to be ergonomically designed with rounded handles and made hollow or made of resin so as to reduce its weight. Although no standard ergonomic specifications have been laid down for hand instruments as yet.

Forceful/exertional movements of hand and wrist into an abnormal/awkward postures such as in performing difficult extractions, prolonged continuous working without breaks/micropauses, or alternation of hand and forearm muscles; mechanical stresses to digital nerves from sustained grasps on sharp edges of instrument handles, forceful work, and extended use of vibratory instruments are also detrimental.

Prolonged increase pressure (active/passive) in the carpal canal can lead to carpal tunnel syndrome; this raised pressure in the carpal canal can be due to repetitive work/forceful work/long-term use of vibratory instruments.

While performing the dental procedures, the most common arm movements are the flexion and abduction, these arm movements are most detrimental when carried out above the shoulder level, as it produce torque on rotating cuff equivalent to nine times the upper-limb weight.[8]

Lower back pain

Good posture correlates negatively with back pain. Low backache has varied number of causes, but the twisting of lumbar spine along with flexion is the most detrimental. These are further aggravated by inflexibilities around the hips and pelvis as well as relative weakness of the stabilizers of the lumbar spine including the abdominal and gluteal muscles. Other contributory factors for backache are abnormal postures, relative weakness, and decreased endurance.

It must be noted that in unsupported sitting, pressure in the lumbar spinal disks increases 40% above the pressure from standing. During forward flexion and rotation, a position often assumed by dental operators, the pressure increases 400% making the structure vulnerable to injury leading to spinal disk herniation and degeneration.[3]

Prolonged Static Postures

To achieve visibility and accessibility, to perform high finesse dental preparations, dentists assume prolonged static postures (PSPs), these are more tiring than the dynamic postures. Dentists can acquire the PSPs despite maintaining ergonomic/balanced working posture. Any deviation from neutral position, the muscles contract is harder to maintain a working posture. Prolonged static contractions of cervical/trunk muscles lead to muscular fatigue/pain/tear. As muscles become fatigued, this prolonged contraction can cause muscle ischemia. Moreover, subsequently, muscle necrosis can occur. Furthermore, when joints are restricted due to muscle contractions, synovial fluid production is reduced, and joint hypomobility may result.

[TAG:2]Symptoms of Musculoskeletal Disorders[3],[9][/TAG:2]

  • Numbness in fingers and hands
  • Hypersensitivity in fingers and hands
  • Weak grip, cramping of hand
  • Clumsiness and dropping of objects
  • Excessive fatigue in the shoulders and neck.


[TAG:2]Signs of Musculoskeletal Disorders[3],[9][/TAG:2]

  • Loss of normal sensation
  • Loss of normal movement
  • Decreased range of motion
  • Decreased grip strength
  • Lack of coordination.



  Prevention, Coping, and Intervention Strategies Top


Ergonomics planning

Ergonomic planning is indispensible for maintaining musculoskeletal health to ensure longer, stress free, and healthier careers with enhanced productivity; providing safer workplaces; and preventing therapeutic errors. Ergonomic hazards/nuances/mishaps can be managed using multidimensional approach including preventive education, postural and positioning strategies, using ergonomic equipment, frequent breaks with stretching, and postural strengthening techniques. An improper posture causes premature fatigue, pain, stress, negative attitude to work, and early retirement.

The ergonomic posture is when the dentist dwells in a natural, unforced, symmetrical, and stress-free position, this posture is comfortable physically and psychologically. It needs to be emphasized that the back is straight and curling of back avoided, forward inclination of trunk to a maximum of 20°, lateral tilting and rotation of trunk are best to be avoided. Flexion of neck up to 20°–25°. The arms placed closed to the body, flexed up to 10°, the forearms raised up to 25° from the horizontal line, the angle between the thighs and shanks of 105°–110°, the thighs apart up to 45°, and the shanks oriented perpendicular to the floor or slightly posterior. The postural symmetry implies all the body horizontal lines (the eyes, shoulders, elbows, hips, and knees horizontals) being parallel and perpendicular to the median line of the body. The balanced posture can be active/passive. The active balanced posture involves the dentist supporting the back straight only by means of paravertebral muscles tonicity. The passive balanced posture is characterized by the use of lumbar support provided by the seatback.[10]

Dentists also tend to dwell into static postures for significant amount of time and perform high finesse dental procedures, these PSPs have appreciable contribution to the MSDs. To maintain ergonomic/balanced posture for long time requires static muscular effort, and this static work is surprisingly more tiring than dynamic work due to continuous long-term firing of impulses from proprioceptors of muscles/tendons/joints to cerebral cortex and subsequent excitation of these nerve centers. Unlike dynamic work, the muscle pump is not functional in static work; hence, the oxygen supply is compromised in static work resulting in pain/fatigue. Dynamic way of working is always beneficial, by employing the active balanced posture and the passive balanced posture alternatively, using the short breaks between the patients to leave the stool and walk, a working program with long demanding treatment sessions alternating to short and easier ones, performing simple exercises between patients. Furthermore, alternatively standing and sitting positions can be used while working as it shifts the load from one group of muscles to another.

Redesigning the workstation

The skill of practicing motion economy must be developed, so that energy can be conserved while performing a task. Avoid awkward movements to reach equipments, keep the instruments and materials within an arms length. The objective is to minimize the number and magnitude of motions.

It must be noted that the most effective way to remedy ergonomic hazards causing MSDs is by customization of the workstation to meet the individual dentist's needs. This can be achieved by (a) using the four-handed dentistry, i.e., operator and assistant working together with the stool position of assistant slightly higher than the dentist's stool, also maintaining the discipline of operators zone, assistants zone, static zone, and transfer zone, (b) instruments/materials to be easily accessible to the dentists, preferably at arms length, and (c) easily adjustable patients chair and lumbar/thoracic/arms support in dentists stool.

Lighting and magnification

Adequate illumination during examinations and procedures is crucial to ensure that important details are not overlooked by the naked eye. The basics of good dental lighting are universal; Adequate brightness to reduce eye fatigue, optimal color rendering index to ensure accurate diagnosis, and easy ergonomic positioning to support healthy posture by reducing clinician movement.

An overhead LED dental light offers the highest degree of uniform light, which illuminates the mouth with minimal shadowing. Another important lighting consideration is the ratio of light between the “target” and the “background”. This target-to-background ratio impacts both visual acuity and eye comfort. Studies suggest a 3:1 TB ratio for best visibility and eye comfort. Lack of an optimal TB ratio may lead to eye fatigue for dental professionals.

The dental operating microscope is different from that of loupes in that it offers stereoscopic vision compared to loupes with its convergent vision. The advantages of using the microscope are healthy, upright working posture along with shadow-free lighting. To put it crudely, the microscope can “hump up” for us, as we sit in highly ergonomic and upright position keeping the spine straight. Good ergonomics allow longer working time without repetitive muscle strain. Latest innovation in magnification aids is heads-up display, where the doctor can monitor patient while operating.

Instrumentation

Use larger diameter, balanced instruments with hollow or resin handles: they increase tactile sensitivity and reduce clinician fatigue. Thin instruments (diameter 1/4 or less) are difficult to grasp and increase the chance of muscle cramping. An instrument with a sharp blade will be less fatiguing to the clinician and contribute to the efficacy of work. Handles should be textured to reduce slippage, but should not be contoured. Round and knurled handles are preferred. Grip span should be curved and comfortably fit the palm of the hand (4“–5”).[1],[4]

Delivery systems

In four-handed dentistry, the dentist maintains a position around the operating field with limited hand, arm, and body movement, and confines eye focus to the working field. Transthorax (or over-the-patient) delivery systems decrease twisting and shift of vision, and dentist should position instruments within easy reach.[1],[9]

Trigger points

The goals of myofascial trigger point therapy are to improve blood circulation to the trigger zone, stretching of the taut band, and release of surrounding fasciae. There are several ways to treat trigger points. Manual trigger point therapy, dry needling, and the combination of these two techniques have been shown to be highly effective. Manual trigger point therapy includes specific manipulations to the muscles, fascia, and connective tissues. Dentists can use a physical therapist trained in trigger point therapy, contract and relax method, or muscle energy technique, or use self-administering trigger point therapy using a small ball between the back and a wall or using a trigger point self-massage tool.

Dry needling includes the use of sterile disposable acupuncture needles to improve circulation and blood flow to the affected muscle trigger point areas. This helps to promote healing and reduce pain. The more accurate the treatment is on the affected trigger point, the better the results.

Periodic breaks and chairside directional stretching[1]

While working pauses/micropauses are indispensible for the dentists, so as to leave the awkward postures and walk around or to perform stretches and let the muscles relax, these micropauses are crucial in injury prevention program. Directional stretching should be performed, including a rotation, side bending, or extension component that usually is in the opposite direction of that in which the operator frequently works.

Strengthening exercises

Dentists should perform specific strengthening exercises for the trunk and shoulder girdle to improve the health and integrity of the spinal column, maintain good working posture, optimize the function of the arms and hands, and prevent injuries. Areas to strengthen include the trunk stabilization muscles, basically the transverse and oblique abdominal muscles and multifidus muscles; the stabilizing muscles of the shoulder girdle, mainly the middle and lower trapezius muscles; and the downward gliding muscles of the rotator cuff, the infraspinatus, subscapular, and teres minor muscles. Dentists should avoid over strengthening the chest and anterior neck musculature, deltoid muscles, and upper trapezius muscles, as this may aggravate muscle imbalances to which they are prone. Parts to stretch include the chest musculature, hamstring muscles, low back muscles, buttock (piriformis) muscles, and hip flexor (ilio psoas) muscles.[1]

Aerobic exercise

Aerobic exercise must be performed 3–4 times a week for at least 20 min. Aerobic exercise increases blood flow to all tissues and improves their ability to use oxygen.

Cognitive behavioral therapy

Dentists with work-related MSDs show a significant tendency to be more dissatisfied at work and to be more burdened by anxiety, experiencing poorer psychosomatic health, and feeling less confident. Cognitive-behavioral therapy (CBT) along with ergonomics and physical exercise is beneficial in such cases. CBT programs comprise pain education and training in cognitive and behavioral skills for coping with pain, identifying, and challenging pain-related negative thoughts.


  Discussion Top


Low back pain was reported to be the most common (54%) MSDs among dentists, and also low back pain is the single worst area of pain (48%). The systematic literature review suggests that the prevalence of general MSDs among dentists varies between 64% and 93%, with the most commonly cited regions of pain being the back (36.3%–60.1%) and neck (19.8%–85%).[5],[7],[11] All studies confirm that sickness absence is much more frequent for back pain than any other body site.[12] Significantly higher pain intensities are reported on right side compared to left for shoulder, elbow, and wrist/hand regions.[13] Females dentists are affected more with MSDs compared to males.[2],[5] The mean age of reported pain onset was 19 years for each of the problems studied, with a standard deviation of 3.5 (neck) to 3.9 (lower back) years.[13] There is a significant correlation between prolonged daily working hours and/or increased job demands, work experience and ergonomic training with the prevalence of MSDs (P < 0.05).[6],[13] Furthermore, psychological factors may affect fatigability and recovery. Regular exercise may provide relief from high physiological and psychological demands of the job. Occupational health educational programs such as ergonomic workplace adaptation, work organization, and psychological coping skills help in preventing risks of MSDs.[13] Long working hours (59.7%) and not maintaining working position (40.3%) are items worsening pain at the end of the day. When working hours go beyond the tolerance of the worker, pause becomes a physiological need. These pauses release lactic acid built up by the prolonged postures, improving tissue oxygenation.[8] Perceived general health has the strongest impact on the occurrence/chronicity/comorbidity/medical care seeking for MSDs.[12]

[TAG:2]Conclusion[3],[9],[12],[13][/TAG:2]

A multidisciplinary approach with primary prevention, early intervention, and continuous education about the potential effects of dentistry-related risk factors should be employed. In a systematized manner, MSDs are to be intervened firstly by reestablishing the ergonomic and cognitive behavioral aspects in the workstation, followed by consultation with neuromuscular therapists, trigger points to be taken care of before attempting any strengthening exercise, strengthening the major stabilizers, physiological pauses, and chairside directional stretching. Further development of dental ergonomics must take place on the basis of a coherent vision of the future. Right ergonomics along with regular exercises, relaxation techniques (meditation, biofeedback, and yoga), and proper nutrition help us combat stress, thus conserving the productive energy, thereby increasing comfort, improving the quality of life, and ultimately leading to extended careers.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

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Abdolalizadeh M, Jahanimoghadam F. Musculoskeletal disorders in dental practitioners and ergonomic strategies. Anat Sci 2015;12:161-6.  Back to cited text no. 1
    
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Pendyala S, Karunakar P. Ergonomics in dentistry-designing your work. J Acad Dent Educ 2014;1:45-50.  Back to cited text no. 4
    
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Bhagwat S, Hegde S, Mandke L. Prevalence of musculoskeletal disorders among Indian dentists: A pilot survey with assessment by rapid entire body assessment. World J Dent 2015;6:39-44.  Back to cited text no. 5
    
6.
Tamrooiy FR, Javar MA, Salimi S, Mohammadpour H, Avakh A, Faizollahi S. A survey on prevalence of musculoskeletal disorders in dentists of Tehran and their posture assessment by RULA Method. International Research Journal of Applied and Basic Sciences. 2015;9:66671.  Back to cited text no. 6
    
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Reddy KS, Majumder DS, Doshi D, Kulkarni S, Reddy BS, Reddy MP. Occupational hazards in dentistry. J Res Adv Dent 2017;6:110-22.  Back to cited text no. 7
    
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Garbin AJ, Garbin CA, Arcieri RM, Rovida TA, da Graca Fagundes Freire AC. Musculoskeletal Pain and Ergonomic Aspects of Dentistry. Rev Dor. São Paulo 2015;16:90-5.  Back to cited text no. 8
    
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Gupta A, Bhat M, Mohammed T, Bansal N, Gupta G. Ergonomics in dentistry. Int J Clin Pediatr Dent 2014;7:30-4.  Back to cited text no. 9
    
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Pirvu C, Patrascu I, Pirvu D, Ionescu C. The dentist's operating posture-ergonomic aspects. J Med Life 2015;7:177-82.  Back to cited text no. 10
    
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Vijay S, Ide M. Musculoskeletal neck and back pain in undergraduate dental students at a UK dental school-a cross-sectional study. Br Dent J 2016;221:241-5.  Back to cited text no. 11
    
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Alexopoulos EC, Stathi IC, Charizani F. Prevalence of musculoskeletal disorders in dentists. BMC Musculoskelet Disord 2004;5:16.  Back to cited text no. 12
    
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Feng B, Liang Q, Wang Y, Andersen LL, Szeto G. Prevalence of work-related musculoskeletal symptoms of the neck and upper extremity among dentists in China. BMJ Open 2014;4:e006451.  Back to cited text no. 13
    




 

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  In this article
Abstract
Introduction
Pain Assessment ...
Classification o...
Risk Factors for...
Mechanisms Leadi...
Symptoms of Musc...
Signs of Musculo...
Prevention, Copi...
Discussion
Conclusion[...
References

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