Abstract
In the dental profession back pain is a common problem. Risk factors are multifactorial and in many cases are parts of the dentists working habits. Prevention is the most effectual way to enhance dentists’ health and health care quality performance. The aim of this essay is to review the literature on back pain among dentists, role of dental ergonometrics, prevention strategies and highlight relevant related musculoskeletal disorders.
Introduction
Back pain is a common disorder that affects people of all ages; some consider it second only to common cold. In most industrialised countries its prevalence is 70% with an annual incidence between 15 to 20%. Besides pain, it has a considerable social and economic impact and it is a common cause of disability for people under 45 years (the main work-force bulk). Further, it is a common cause for increased health care expenditure, since healthcare costs in USA has increased 65% from 1997 to 2005 for back pain patients without spinal problems. Mechanical or musculoskeletal back pain is the term used for patients with no recognizable cause (e.g. disc prolapsed, tumour…) (Bahangle et al 2009).
In the dental profession (dentists and dental hygienists) back pain is a common problem. Several reasons are responsible for this disorder among dentists; first, dentists spend their working time in an uncomfortable static position working in a narrow work space (the oral cavity). Second, because error is not tolerated, they keep a steady posture and a steady hand which are achieved on the expense of the back, neck and shoulder.
The discomfort ranges from occasional pain felt at irregular positions attained during work to regular pain that becomes cumulative in nature resulting in disability. The dentists suffering from pain may have reduced productivity in terms of decreased work time, or inefficient movements during work; thus, increasing the time spent per patient (Chowanadisai et al 2000). The aim of this essay is to review the literature on back pain among dentists and highlight relevant related musculoskeletal disorders.
Background
Although Scully et al (1990, p. 6) described modern dentistry as one of the least hazardous occupations, evidence suggests that there are many risks in the dental profession to question this assumption. Leggat et al (2007, p. 611) suggested there are physical hazards that include exposure risks like exposure to infection, bio-aerosols, noise, radiation and exposure to dental material. In addition, percutanous incidents, eye injuries, vibration induced neuropathy and musculoskeletal disorders are common physical perils specific for dentists. Further, Rada and Johnson-Leong (2004, p. 788) pointed that dentists are prone to professional burn-out, anxiety and clinical depression because of the nature of dental clinical practice. They suggested that dentists should look at maintaining good psychological health and understand the implications of stress.
Apart from biological and psychological hazards, musculoskeletal disorders of the back, neck and shoulders show high prevalence (Leggat et al 2007). Puriene et al (2007) studied the factors that link to this high prevalence and inferred that education level and working without breaks are significant correlating factors. In addition, musculoskeletal back pain starts at an earlier age among dentists, even 70 % of dental student complain of back pain. Puriene et al (2007) recognized the vascular, neural and osteo-articular harms associated with vibration and the chair-dentist interface and posture biomechanical effects; however, they stressed on risk factors for back pain among dentists is multifactorial and prevention should include strategies addressing defects in in operator position, posture, flexibility, strength and ergonomics.
Palmer et al (2000) suggested that nearly 49% of adults in the UK reported back pain that lasted at least 24 hours in the year, and nearly 4 out of five UK adults complained of back pain at some time in their life. Since dentists are part of the community, it appears necessary to educate the professionals of how to prevent such risks. Besides seeking medical advice for the slightest musculoskeletal discomfort, dentist should be aware that prevention is an important line of management of back pain (Health and safety executive n.d.).
It is essential to define chronic back pain before proceeding, Andersson (1999, p. 581) defined back pain as back pain that lasts for 7-12 weeks or more. Others recognise frequently recurring back pain as chronic, while many consider pain that lasts beyond the expected period of recovery is chronic back pain. Industrial and insurance sources look at chronic back pain in terms of disability or lost days of work; thus, the problem is not only absence of a universally accepted definition of chronic back pain but also absence of work disability measures and compensation guidelines (Andersson 1999).
Second, is defining repetitive strain injury (RSI), which covers well-known conditions such as tennis elbow, flexor teno-synovitis and carpal tunnel syndrome. It is commonly caused or aggravated by work associated with repetitive and over-forceful movement, excessive workloads, inadequate rest periods and sustained or constrained postures. This results in pain or soreness due to inflammation of the muscles and the synovial lining of the tendon sheath. Signs and symptoms of RSI include localized pain, tenderness, swelling and a grating sensation in the joint (crepitus) aggravated by pressure or movement (Stranks 2002).
Classification of back pain among dentists
Since the scope of this thesis is to review back pain in a specific group of the population (dentists), classification can be looked upon from a biophysical perspective, also known as a person-centred rather than a disease- based approach. It recognizes the interaction of biomedical or physical factors with psychological and behavioural influences in addition to social factors, which include family, culture and occupation. When considering a person who is troubled by a regional pain problem of the upper limb or back, it is helpful to think in terms of predisposing factors, precipitating factors and perpetuating factors.
This assists problem solving by identifying clinical, emotional, cognitive, social or environmental factors that may be influenced by intervention to promote restoration of function and symptom relief. For example, precipitating factors for back pain may be biomechanical: minor trauma, change of equipment, change of work or recreational routines, excessively long hours of work leading to muscle fatigue.
Psychosocial: poor job satisfaction, interpersonal difficulties, personal problems and negative life events. Successful management of a person with these disorders demands that the clinician makes a confident diagnosis and identifies perpetuating factors and obstacles to recovery. Communicating with other professionals such as occupational health staff is very important for optimal outcome since these disorders are easier to treat in the early stages (Brown 2005).
Musculoskeletal disorders are considered occupational when work related body pain is associated with physical strain affect these areas during the work course in the absence of other causes. Thus, work related musculoskeletal disorders can be classified to three general categories; traumatic, irritation of musculoskeletal tissues and accelerated degenerative changes. Irritation of musculoskeletal tissues results from repeated functioning of these tissues in un-physiological way, thus are considered to repetitive strain injuries (Tak-sun 1992).
From a pathological viewpoint, Kinkade (2007) classified back pain to nerve roots syndromes characterised by radicular pain and results from disc herniation, inflammation or irritation. Second, the musculoskeletal pain syndromes that include myofascial pain and fibromyalgia; finally, the non-mechanical skeletal pain syndrome that include sacroiliitis, tumours or osteomyelitis.
Mechanisms of back pain among dentists
Prolonged sitting with limited movement produces biomechanical and physiological effects. The biomechanical strain placed on the musculoskeletal system depends on the posture adopted, which controls the loading on the lumbo-sacral region considered the weakest point of the vertebral column as a kinetic chain. Posture adopted during work depends, in turn, on how the individual’s body dimensions relate to the different items in the work space, which is called dimension compatibility. Another factor to consider is the force (s) acting on the vertebral column, which include tension in surrounding contractile tissue (muscles and ligaments), intra-abdominal pressure and external loads.
Normally, the back extensor muscles generate an extensor moment to counteract that of the flexion moment produced by gravity, which is a large forced compared to the small extension arms of the back extensors. Prolonged sitting results in extensor muscles fatigue. The clinical implication for this is unsupported sitting would link to a wilting posture, which increase compression forces on the vertebral column and may result in disc herniation. Therefore, a chair designed to provide efficient lumbar support and reduce spinal loading will contribute to relaxing the extensor back muscles and help to maintain the normal lumbar lordosis (Todd et al 2007).
On working seated for long periods, especially when there is dimension incompatibility resulting in limited movement with reduced dynamic muscle activity. This results in increased capillary net transcapillary filtration and oedema of the lower limbs. Increased venous pressure because of prolonged sitting causes increased capillary hydrostatic pressure, which contributes to oedema. Further, nearly 50% of the body’s muscles contract to hold the body in the bending position of a dentist to resist both gravity and the static forces resulting from taking this posture. This proved to be more demanding than dynamically moving posture.
Finally, limited movement causes localised tension in certain parts of the body depending on the posture adopted. The clinical implication of the above discussion is to show the importance of having suitable rest periods during work time moving, standing and stretching (Nordander 2004).
Valachi and Valachi (2003 a, p. 1344) inferred that causes of musculoskeletal disorders among dentists are multifactorial. Wilt posture adopted leads to increased pressure on disk spaces and reduces spinal mobility; both are factors that accelerate spinal degenerative disorders. Further, prolonged almost static muscle contraction may result in muscle ischemia or necrosis creating a vicious circle.
The question of gender differences in work related musculoskeletal disorders was approached by Nordander (2004, p. 10) who reported these disorders are more common in females compared to male’s dentists. The reasons for this difference can be biological differences making females more vulnerable, or to factors other than those of the work place as family burdens, which can produce an added effect, but not evenly distributed between genders.
Epidemiology of back pain among dentists (disorder statistics)
Epidemiology is the study of the distribution and determinants of disease frequency in man. Such data are needed for further investigations of patterns of disease in subgroups of the population. This definition is based on two fundamental assumptions: First, the occurrence of diseases in populations is not a purely random process. Second, it is determined by causal and preventive factors (Ahrens and Pigeot 2005).
In the mid 1990s Moen and Bjorvatn (1996), doubted that dentistry practice predisposes to musculoskeletal disorders. They conducted across sectional survey study among dentists, dental auxiliaries and office workers and inferred no significant differences in musculoskeletal symptoms existed among groups. In this study, female dentists reported more musculoskeletal symptoms than their male counterparts; however, no significant differences in symptoms reporting between female dentists and other female staff. Nearly in the same period, Finsen et al reported 65% prevalence rate of musculoskeletal symptoms among dentists and Chowanadisai et al (2000) reported 78% prevalence rate.
Al Wassan et al (2001) surveyed 204 dentists and dental auxiliaries in Riyadh, KSA for prevalence of musculoskeletal symptoms. Results showed 73.5% of participants complained of back pain and 54.4% complained of neck pain, unexpectedly, only 37% of those complaining of back pain sought medical advice. In Brazil, Filho and Barreto (2001) surveyed 358 dentists. The highest prevalence rate was for upper limb pain (58%), while back pain accounted for 21% of musculoskeletal complaints. Daily frequency of pain was reported in 26% of participants and 40% classified their pain as moderate to severe. In a multivariate analysis of results, back pain was linked manual activity, neck pain to compressor in the office and indirect vision; while upper limb pain linked to the desire of greater productivity and income increase.
Alexopoulos et al (2004) examined the link between physical work-load, psychosocial and individual traits and musculoskeletal complaints’ end points (back, neck, shoulder). Results showed 62% of dentists had at least one musculoskeletal complaint, 30% had chronic complaints and 16% had periods of work absence. Physical work-load related to the number of musculoskeletal complaints while psychosocial factors showed no significant link to the number of complaints, absence or chronicity.
Reports showed that dentists suffer back pain at earlier onset, which was confirmed by Rising et al (2005) who examined the prevalence of musculoskeletal complaints in dental school students. Body pains were reported in 47 to 71% of the students and increased with increased years of study with most student reporting pains at the third year. Leggat and Smith (2006) reported 87.2% of dentists in Queensland, Australia reported one musculoskeletal symptom in the past year with neck pain representing 57.5%, back pain 53.7% and shoulder pain 53.3%. They inferred that musculoskeletal disorders represent a serious occupational health hazards for dentists.
Puriene et al (2008) conducted a survey designed to focus on the specificity of self-reported complaints in a group of 2449 Lithuanian dentists. Results showed back pain was the most prevalent complaint (42.8% for males and 53.6% for males.
Risk factors for back pain in dentistry
A risk factor is the quality, characteristic, or vulnerability factor, which makes an individual susceptible to a disorder more than a randomly selected individual from the general population. Risk factors should, therefore, precede the onset of the disorder. Risk factors can be unchanging, like gender or altered by interventions, like education level (Ahrens and Pigeot 2005).
Marklin and Cherney (2005) conducted a detailed task analysis study by video- taping four hours long working sessions for dentists and dental hygienists aiming to study their working postures. The group studied was found to have their trunks flexed 30 degrees or more for more than 50% of working time, their necks flexed to the same degree for 85% of the working time. In addition, their shoulders were abducted 30 degrees or more for more than 50% of the working time. Further, posture of the trunks, necks and shoulders were static for the time mentioned. They inferred these postures are important risk factors for musculoskeletal disorders in these regions.
Gandavadi et al (2007) assessed the role of the dentists’ chair as a risk factor for musculoskeletal troubles in two groups of dental students. Their results showed student using ordinary chairs had higher risk scores, while the group used a back support (Bambach) chair had lesser risk score. They suggested that posture can be corrected by using back support chair; thus, minimising risks for musculoskeletal disorders.
Yamalik (2007) in an informative literature review classified musculoskeletal risk factors according to the clinical task undertaken by the dentist. First, is limited range of motion and isometric muscle contraction secondary to confined working area, second, is the indirect visualization of the oral cavity; third, is the visual demands of the task that requires a fixed posture for long periods. Yamalik (2007) also recognised that certain tasks need repetitive movements for long periods, tasks that require forceful procedures and work that needs flexion and stability of the wrist are all risk factors for musculoskeletal disorders. The author inferred that work-related musculoskeletal disorders are parts of oral health providers’ professional life that can hardly be avoided, but can be attended and modified to reduce risks.
Dentist Job demands and back pain
As early as the 1950s, researchers recognized the fact that the practice of dentistry is associated with several musculoskeletal disorders that may be attributable to risk factors found in the typical dental work environment. Since then, advances in dental practice involved three aspects, first, a change of technique from standing to sit down dentistry (Murphy 2001). However current researchers have identified potential risk conditions related to sitting.
Second, advances in tools and equipments as compressed air-driven high-speed hand-pieces replaced the old drills. While the increased speed of the new instruments improves the quality of care and reduces the time required to complete the dental procedure, it has also resulted in vibration-related hand and wrist conditions. A third significant development in dentistry involves the move from a single practitioner, i.e. the dentist, to four-handed dentistry.
This switch now incorporates a professionally trained helper, usually a dental hygienist, into the daily practice. Like most changes there have been benefits such as a reduction in the length of the patient visit due to increased efficiency and there have been liabilities such as the development of work-related musculoskeletal disorders in a whole new cadre of workers (Murphy 2001).
Further, researchers have identified six risk factors for the development of work-related musculoskeletal disorders and they are: repetition, awkward postures, force, vibration, direct pressure, and insufficient rest. In addition, they state that a combination i.e. the presence of more than one risk factor markedly increases the potential for the development of these disorders (Chowanadisai et al 2000 and Yamalik 2007). Hakanen et al (2008) studied the job demands model that integrate working conditions and centers on negative and positive indicators of well being and inferred that work characteristics play a pivot role for health and well being.
Dental ergonometrics and back pain
Ergonometrics simplest definition is the study of the man–machine interface (Stranks 2002, p. 3). There are many issues that ergonometric researcher have to look at to improve dental care work environment and reduce risk to develop musculoskeletal disorders. Sadig (2000) classified the role ergonometric needs to play in dental practice to room design aiming to provide adequate space for comfortable patient management, the instruments should be easily reached. In addition, the dental chair should have a back and arms support, movable and can go up and down. Bridger (2003) focused on the importance of work space compatibility and that it should fit dental tasks design in all elements (appropriate tasks design space, instruments and work environment).
Morse et al (2007) suggested that specific dental procedures put the clinician at increase risk for fingers or hands’ injury; however, posture is a common risk factor to all musculoskeletal disorders. In the same way risk is multifactorial, proper posture depends on many factors like appropriate patient and dentist chairs, proper magnification and visualization and using ergonomically suitable instruments. Morse et al (2007) summarised the factors in dental stool selection to seat angle and depth, back support (height and tilt), shoulder support, adjustability, stability and finally the fabric.
Improving visibility of the working site by direct light and-or magnification results in improving posture habit, precision of work and increased productivity. The requirements of an ergonomically suitable magnification tool besides dentist’s preference are availability of proper space, speed of building up a learning curve, magnification requirements and cost (Spear 2006).
Summary of evidence work-related back pain in dentistry
The Ergonomics and Disability Support Advisory Committee of the American Dental association (2004) recognised back pain and other musculoskeletal disorders as common occupational hazards among dentists. On reviewing the literature, the report outlined the primary occupational risk factors linked to dentistry profession and included repetition defined as the average number of movements or efforts done by a joint or a muscle within a unit of time
. Second is force defined as the mechanical effort done to complete a movement, the report defined mechanical stress risk factor as the impact or injury resulting from using, grasping, balancing or manipulating an equipment or instrument. Posture was identified as a major risk factor and was defined as the position of a body part relative to the nearest part in terms of the angle of the joint connecting these parts.
The report identified whereas vibration is a risk factor at frequencies between 20-80 Hz, dental hand pieces and other powered dental instruments produce vibration at 5000 to 10000 Hz. Thus, even with short periods of exposure, dental vibrating instrument are capable of producing musculoskeletal disorders. Finally, the report identifies the importance of external stress factors like nature of the work process and work load time pressure. The report recognized that back pain in dentists is multifactorial and attention should be given not only to the end point organ but also to the possible underlying biochemical and physical condition that precipitate or aggravate the condition.
Prevention of dentists work-related back pain
There are three strategies for work-related back pain among dentists; first, primary prevention aiming at taking action on the determinants of health like adopting good posture and proper ergonometrics. It is like changing the focus of attention upstream to prevent people from getting wet by the waters of musculoskeletal disorders (UK Department of Health 2007). The only indicator that workplace interventions targeting primary prevention produced an effect on important outcomes such as sickness absence is the spread of information and beliefs of the importance and prevalence of the disorder.
The primary prevention of back pain, and upper limb pain as a symptom, is an unrealistic goal. At present, the most effective strategies for primary prevention in the workplace appear to be good working relationships and probably good ergonomic and job design factors for upper limb pain, although evidence for this assumption remains scarce (Buchbinder 2001).
Secondary prevention is largely to detect the disorder at an early stage and pursue appropriate intervention as treatment or health promotion (UK Department of Health 2007). This strategy aims to prevent disability and chronicity of the developed musculoskeletal disorder. The occupational health professional has the chance to see dentists with back pain early in the course of the disorder and thus influence the outcome in a positive way. The first consultation with a health-care expert is probably the most important since the symptoms relate problems are still vivid (Brown 2005, p. 43).
Tertiary prevention aims to reduce the effects of the disease and improve the quality of life through active rehabilitation (UK Department of Health 2007). Since the precipitating and perpetuating factors are many, management needs to be multimodal, and the affected dentist needs to be motivated to contribute actively in the rehabilitation plan and take responsibility for maintaining the management program. At this stage, the work place needs reassessment and interventions based on ergonometrics and correcting work habits are of importance. To proceed with the rehabilitation program, the dentist may need support and encouragement to overcome the secondary psychological impact, difficulties and setbacks (Bailoor and Nagesh 2005).
Strategies for primary prevention addressing defective dentists’ posture and dental students’ training and education exist, but with limited success. Although it seems easier and more effective; yet, evidence suggested by the voluminous literature on the prevalence of back pain among dentists is clear and casts shadows of the success of primary prevention interventions (Lungeanu et al 2008). Valachi and Valachi (2003 b, p. 1604) inferred a comprehensive approach towards prevention of the disorders should integrate a multifactorial multistage outlook.
Other relevant work-related musculoskeletal disorders for dentists
Dental hygienists are the commonest health care professional to suffer from work-related neck pain (72%). Dentists are affected by neck musculoskeletal disorders with a prevalence rate of 17%, with an annual prevalence rate as high as 66%. Each year 5.1% to 6% of dentists suffer from work-related neck pain (Cote et al 2008). Prevalence of shoulder pain among dentists varies from 38% to 65% in different studies from different geographical locations having posture and ergonometrics as the commonest risk factors similar to back pain (Leggat et al 2007).
Although the commonest upper limb work-related disorder, shoulder pain is not the only one. Several other disorders are perpetuated by repetitive strain injury like carpal tunnel syndrome and de Quervain disease. A UK study reported 1.3% prevalence rate for lateral epicondylitis. In the same study, prevalence rates of de Quervain disease was 0.5% in males and 1.3% in females and tenosynovitis in 1.1% of males and this rate is doubled in females (van Tulder et al 2007).
Dentists show high prevalence rates of finger-related and interphalangeal joints disorder (e.g. arthrosis) mainly related to longer periods of dental filling and root treatment work tasks. The reason is prolonged use of dental hand pieces producing high frequency vibrations (Rytkonin et al 2006).
Prolonged and regular exposure of the fingers or the hands to vibrating tools can give rise to various signs and symptoms of hand-arm disorder. The disorder may comprise vascular or neurosensory effects, or a combination of both. The vascular effects are characterized by episodic blanching of the fingers precipitated by cold and relieved by warmth. The neurological effects are typically numbness, tingling, elevated sensory thresholds for touch, vibration, temperature and pain, and reduced nerve conduction velocity. In the UK, the disease of hand–arm vibration syndrome entitles the sufferer to apply for compensation from the government through the industrial injuries prescribed disease system (Brown 2005).
Summary and conclusion
This review shows the high prevalence of back pain and other musculoskeletal work-related disorders among dentists. The impact of this problem affects the quality of health care provided and represents an economic burden on the health care and the dentists. It also shows that advances in ergonometrics can positively affect the dentists’ health; however, introducing these advances is not accompanied by providing enough information on the safety and health of the target group involved.
The study also shows that musculoskeletal disorders risk factors among dentists are multifactorial and interacting, they relate to posture, proper selection and use of instruments and tools and most importantly relate to dentists’ work habits. Current evidence suggests that primary prevention strategies, although not achieving full success; yet, they are the best shot to tackle this problem. Therefore, comprehensive versatile approach dealing with education postural strategies, proper use of ergonometric technology advances and awareness of importance of frequent rest periods and stretching needs to focus upon. Dentists need to integrate these practices into their daily work, which may be difficult as it mandates a change in the model of dental practice.
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