Strategies for Preventing Musculoskeletal Disorders

Musculoskeletal disorders (MSDs) are a common occupational hazard, significantly affecting dental professionals’ well-being, work performance, and career longevity. MSDs refer to injuries affecting the musculoskeletal system and often stem from muscle imbalances caused by repetitive motions in prolonged, nonergonomic postures. This imbalance affects muscles, nerves, and skeletal structures, leading to ischemia, muscle necrosis, chronic pain, and fatigue.^1-5

A 2018 systematic review and meta-analysis by Lietz et al¹ on MSD and pain prevalence among dental professionals in Western countries revealed an aggregated annual prevalence rate of 78%. The neck was the most frequently affected body region, with a prevalence of 58.5%, lower back at 56.4%, upper back at 41.1%, shoulders at 43.1%, and hand/wrist at 33.6%.

Causes of Musculoskeletal Disorders in Dentistry

Throughout their careers, dental professionals may spend 60,000 hours working in tense and distorted positions, which can lead to potential musculoskeletal disorders (MSDs). MSDs are a significant contributor to early retirement in dentistry, accounting for 29.5% of such cases.⁶

Clinicians adopt awkward positions for repetitive tasks such as coordinating with assistants, ensuring optimal visibility, providing patient comfort, and handling equipment. Awkward positions include extreme forward-head and neck flexion, trunk inclination and rotation to one side, lifting of one or both shoulders, increased curvature of the thoracic spine, and incorrect positioning of the legs with a hip-thigh angle of less than 90°.⁷ Other contributors include a lack of proper magnification, lighting, indirect vision, and four-handed dentistry. Additionally, cluttered spaces lead to repetitive reaching and stretching.

Procedures demanding forceful exertions, tightly gripping instruments, and retracting strong tissues place higher loads on muscles, tendons, ligaments, and joints. Force requirements increase with awkward postures, faster movements, small tool handles, increased slipperiness of objects, vibration, and specific gripping techniques.⁶

Forward head posture (FHP) significantly contributes to MSDs due to the anterior protrusion of the head and rounded upper back to gain better visibility during treatment. In an investigation of the surgeon’s neck posture, Naresh-Babu et al⁸ estimate that for every inch the head moves forward or 10° of neck flexion, an additional 10 pounds of effective weight is added to the cervical spine. The authors report that the average FHP observed in operating surgeons is 5.3 inches, resulting in a head weight exceeding 50 pounds.

The additional stress on the cervical and thoracic spine requires the upper back and neck muscles to work harder. FHP can be the first domino in a series of muscle imbalances leading to upper crossed syndrome (UCS). The imbalance involves overactive muscles on one side of the neck, countering under-active muscles on the adjacent side, forming an “X” pattern through reciprocal inhibition. This results in the lengthening of muscles on one side to compensate for the contracted muscles on the other side of the joint.⁹ The upper back, shoulders, and neck muscles — particularly the middle and lower trapezius muscles — tend to get long and weak due to under-activity. In contrast, the upper trapezius and levator scapula muscles become overworked and tight.

Over time, prolonged postural imbalance intensifies muscular imbalance, creating a vicious cycle. Clinical presentations of UCS include neck and shoulder pain, muscle tightness, hunched shoulders, headaches, and cervical disc degeneration.^9,10

Treatment Options

Developing effective treatment strategies for MSDs involves a comprehensive approach addressing both symptoms and underlying causes. Early intervention of immediate symptoms may involve physical therapy, chiropractic care, and massage therapy, where qualified professionals can offer targeted exercises and manual therapies for immediate relief from pain and overall improvement of musculoskeletal health.^2,6,10 Self-myofascial release uses foam rollers and balls to massage and compress the affected areas to increase circulation, release trigger points, and rehydrate the connective tissue.

Ergonomic Strategies to Minimize Risk

Ergonomics is the practical science of designing and arranging items used by people to optimize safe and efficient interaction between them. The literature widely acknowledges the importance of ergonomic measures in preventing MSDs, emphasizing maintaining a neutral and balanced posture and utilizing a modern workstation with appropriate ergonomic support.^2,5,7,9,11

The following interventions should be considered in the dental practice:

• Maintaining neutral posture
• Utilization of ergonomic tools in the workstation
• Optimized positioning of clinician and patient
• Strategic scheduling to allow for breaks and stretching

To maintain proper posture while practicing dentistry, sit upright with a neutral spine and pelvis, keeping neck flexion less than 20°, with chin lifted and slightly tucked. Keep shoulders down and back, elbows close to the body, and feet flat and evenly balanced. Sitting with hips slightly higher than knees and a seat angle slightly tilted forward helps maintain the low back curve and prevent low back pain.

Ergonomic loupes reduce strain with features such as prismatic lenses with a steep declination angle, working length and width adjustability, reduced weight, improved magnification, and focused lighting. Traditional loupes provide relatively small declination angles (20° to 25°), which require practitioners to look down and maintain a FHP, contributing anywhere from 20 to 50 lbs of effective weight to the cervical spine. Even with steeper declination angles, traditional loupes increase eye strain.¹²

Newer ergonomic loupes using prism technology can offer declination angles up to 60° to 80°. Prismatic loupes mimic a microscope, allowing practitioners to look straight out and down, eliminating FHP and the resulting muscle imbalances. Lindegard et al¹³ investigated the ergonomic benefits of using prismatic glasses during dental procedures. They found that a reduction in head and neck flexion achieved by the prismatic glasses will likely reduce clinicians’ risk of neck pain during dental work.

Additionally, practicing four-handed dentistry, correctly positioning the instrument table, and regularly reorganizing operatory storage can reduce excessive leaning, twisting, and bending. Transthoracic (over-the-patient) systems minimize twisting.^2,10 Consider the periodic evaluation of tools, as employing sharp instruments helps decrease the need for excessive force during procedures. When possible, utilize automatic instruments, such as ultrasonic scalers or rotary files. Additionally, visual documentation can aid in evaluating working posture and supporting continuous improvement.

Patients should recline fully for tasks involving the maxillary arch or a 20° angulation when working on mandibular teeth.⁵ Elevating the patient chair allows the mouth to align with the clinician’s elbow to avoid raised arms and shoulders and facilitates free thigh movement to ensure unimpeded access to the patient’s head, especially for right-handed operators working from the 7 to 12:30 o’clock positions.⁶

Clinicians should choose adjustable seating that ensures lumbar and arm support. Tilting the clinician’s seat angle slightly forward (5° to 15°) enhances the low back curve and maintains a hip angle greater than 90°, which allows for closer positioning to the patient.^2,10 Consider using a saddle stool to promote a more natural, neutral spine position, alleviating pressure on the lower back. Additionally, alternating between sitting and standing may be helpful. Lastly, positioning the light source directly above and slightly behind the patient’s oral cavity optimizes visibility and illumination during procedures.

Task rotation, posture shifting, and alternating between easy and challenging cases can mitigate muscle strain resulting from prolonged, repetitive, and awkward postures. Short stretches every 45 to 60 minutes can increase blood flow, joint fluid production, and nutrient supply while promoting relaxation.^2,10 Stretches should be opposite to the frequent work postures, two to three times daily, even while seated in the dental chair, during short breaks (eg, 30-second breaks between treatments).¹¹ Notably, the emphasis should be on frequent, brief stretches, which are more advantageous than longer, infrequent stretching sessions.

Prevention of Musculoskeletal Disorders

MSDs can be caused by muscle imbalances stemming from the ergonomic challenges inherent to practicing dentistry. The approach to preventing MSDs and addressing muscle imbalances, such as UCS, involves stretching tight muscles to alleviate tightness and improve flexibility and strengthening weak muscles to address muscular imbalances and provide stability.^2,10,11

Holzgreve et al¹⁴ evaluated the impact of a 10-week trunk-oriented resistance training program on pain intensity and ergonomic risks experienced by dental assistants and dentists. The results indicated significantly reduced pain intensity and improved maximum voluntary isometric contraction in trunk muscles.

Another paper by Jones and Forsythe¹⁵ presents a tailored exercise prescription for oral health professionals, focusing on functional training to address the specific physical challenges of dental work. The authors emphasize torso training, often known as core training, which stabilizes the shoulders, abdominals, and hips. Another study by Kumar et al¹¹ explores exercise prescriptions as a preventive measure against musculoskeletal disorders in dentists.

Combining the findings of these studies yields a comprehensive list of recommended exercises for dental professionals to prevent MSDs to enhance strength, flexibility, and overall musculoskeletal health. Effective stretches such as neck rolls, chest openers, backbend variations, forward and side bending, and lunge variations target short, tight muscles such as the upper trapezius, levator scapula, pectoralis, erector spinae, and iliopsoas (see Figures 1 through 8).^9,16

Effective strengthening exercises, such as neck retractions (chin tucks), scapular squeezes and rowing, prone arm raises, back extensions, core stabilization, trunk rotation and flexion, and glute activation exercises, strengthen weak, under-active muscles such as the deep neck flexors, lower trapezius, serratus anterior, abdominals, and gluteus maximus.^11,14,15 Additionally, engaging in aerobic exercises three to four times per week for a minimum of 20 minutes is recommended to improve the delivery of nutrients and oxygen to the muscles and reduce the risk of developing MSDs.^2,10

Beyond physical training, making behavioral and lifestyle modifications and encouraging healthy lifestyle habits, including stress management, contribute to preventing and managing MSDs. Stress has the potential to induce muscle contraction and pain. Dentists should prioritize stress management techniques, including mindfulness practices, deep breathing exercises, and relaxation techniques.^2,9,10

Yoga offers a unique and practical approach to musculoskeletal health and stress management. Yoga is an ancient system, dating back to 3000 BC in the Indian subcontinent, encompassing relaxation, exercise, and healing that can be practiced daily for overall well-being. Numerous studies highlight yoga’s efficacy in alleviating stress and anxiety, impacting both physical and mental health conditions.¹⁷

Koneru and Tanikonda¹⁸ found that practicing yoga can help reduce musculoskeletal pain among dentists, especially those working more than 50 hours per week. Yoga strengthens the musculoskeletal system and helps reduce stress by triggering the release of beneficial hormones. The special breathing and meditation techniques inherent to yoga positively influence the central nervous system to improve pain control and tolerance. They also found that regular yoga practice is more effective than other physical activities in reducing pain, possibly due to its controlled, consistent nature and positive effects on the musculoskeletal system and psychological well-being.

Similarly, a study by Gandolfi et al¹⁶ developed an in-office yoga protocol for dental professionals to prevent MSDs. This protocol includes sitting and standing asanas (yoga poses) targeting areas such as the neck, upper back, chest, shoulder girdle, and wrists to mobilize, decompress, and nourish the musculo-articular system.

Yoga is a means to restoring muscle flexibility and mobility, alleviating strain, and enhancing overall physical and mental well-being through stretching and strengthening, breath-driven movement (vinyasa), focused attention, self-awareness, and mind–body connection. The approach combines physical exercise with mindfulness, offering dental practitioners a well-rounded strategy for preventing musculoskeletal issues and managing stress.¹⁶

Conclusion

Dental professionals should adhere to a stretching and strengthening regimen. Yoga offers a holistic approach to prevent MSDs and manage stress. Comprehensive literature highlights the significant health impact of MSDs on dentists, affecting their well-being and career longevity. Combining ergonomic adjustments, targeted exercises, and stress management can help mitigate these risks.

References

1. Lietz J, Kozak A, Nienhaus A. Prevalence and occupational risk factors of musculoskeletal diseases and pain among dental professionals in Western countries: A systematic literature review and meta-analysis. PLoS One. 2018;13:e0208628.
2. Chopra A. Musculoskeletal disorders in dentistry — a review. JSM Dent. 2014;2:1032.
3. Hayes M, Cockrell D, Smith DR. A systematic review of musculoskeletal disorders among dental professionals. Int J Dent Hyg. 2009;7:159-165.
4. Morse T, Bruneau H, Dussetschleger J. Musculoskeletal disorders of the neck and shoulder in the dental professions. Work. 2010;35:419-429.
5. Kumar M, Pai KM, Vineetha R. Occupation-related musculoskeletal disorders among dental professionals. Med Pharm Rep. 2020;93:405-409.
6. Gupta A, Bhat M, Mohammed T, Bansal N, Gupta G. Ergonomics in dentistry. Int J Clin Pediatr Dent. 2014;7:30-34.
7. De Sio S, Traversini V, Rinaldo F, et al. Ergonomic risk and preventive measures of musculoskeletal disorders in the dentistry environment: an umbrella review. PeerJ. 2018;6:e4154.
8. Naresh-Babu J, Arun-Kumar V, Raju DGS. Surgeon’s neck posture during spine surgeries: “the unrecognised potential occupational hazard.” Indian J Orthop. 2019;53:758-762.
9. Raja SR, Prem BR, Triveni MG, Tarun ABK, Ravi SPL, Dhoom M. Upper crossed syndrome and dentistry: why the need for concern. Biomed J Sci & Tech Res. 2017;1:1-2.
10. Valachi B, Valachi K. Preventing musculoskeletal disorders in clinical dentistry: strategies to address the mechanisms leading to musculoskeletal disorders. J Am Dent Assoc. 2003;134(:1604-1612.
11. Kumar DK, Rathan N, Mohan S, Begum M, Prasad B, Prasad ER. Exercise prescriptions to prevent musculoskeletal disorders in dentists. JClin Diagn Res. 2014;8:ZE13-ZE16.
12. Chang BJ. Declination angle: the key factor for custom loupes. Oral Health Group. Available at: oralhealthgroup.com/​features/​declination-angle-the-key-factor-for-custom-loupes-b-j-chang-phd. Accessed June 11, 2014.
13. Lindegård A, Gustafsson M, Hansson GÅ. Effects of prismatic glasses including optometric correction on head and neck kinematics, perceived exertion and comfort during dental work in the oral cavity — a randomised controlled intervention. Appl Ergon. 2012;43:246-253.
14. Holzgreve F, Fraeulin L, Maurer-Grubinger C, et al. Effects of resistance training as a behavioural preventive measure on musculoskeletal complaints, maximum strength and ergonomic risk in dentists and dental assistants. Sensors (Basel). 2022;22:8069.
15. Jones AC, Forsythe S. Functional training for dentistry: an exercise prescription for dental health care personnel. J Calif Dent Assoc. 2005;33:137-145.
16. Gandolfi MG, Zamparini F, Spinelli A, Prati C. ĀAsana for neck, shoulders, and wrists to prevent musculoskeletal disorders among dental professionals: in-office yóga protocol. J Funct Morphol Kinesiol. 2023;8:26.
17. Nayak NN, Shankar K. Yoga: a therapeutic approach. Phys Med Rehabil Clin N Am. 2004;15:783-vi.
18. Koneru S, Tanikonda R. Role of yoga and physical activity in work-related musculoskeletal disorders among dentists. J Int Soc Prev Community Dent. 2015;5:199-204.

From Decisions in Dentistry. June/July 2024; 10(4):42-45