Ergonomic interventions for preventing musculoskeletal disorders in dental care practitioners
Dentistry is a profession with a high prevalence of work‐related musculoskeletal disorders (WMSD) among practitioners, with symptoms often starting as early in the career as the student phase. Ergonomic interventions in physical, cognitive, and organisational domains have been suggested to prevent their occurrence, but evidence of their effects remains unclear.
To assess the effect of ergonomic interventions for the prevention of work‐related musculoskeletal disorders among dental care practitioners.
We searched CENTRAL, MEDLINE PubMed, Embase, PsycINFO ProQuest, NIOSHTIC, NIOSHTIC‐2, HSELINE, CISDOC (OSH‐UPDATE), ClinicalTrials.gov, and the World Health Organization International Clinical Trials Registry Platform (ICTRP) Search Portal to August 2018, without language or date restrictions.
We included randomised controlled trials (RCTs), quasi‐RCTs, and cluster RCTs, in which participants were adults, aged 18 and older, who were engaged in the practice of dentistry. At least 75% of them had to be free from musculoskeletal pain at baseline. We only included studies that measured at least one of our primary outcomes; i.e. physician diagnosed WMSD, self‐reported pain, or work functioning.
Data collection and analysis
Three authors independently screened and selected 20 potentially eligible references from 946 relevant references identified from the search results. Based on the full‐text screening, we included two studies, excluded 16 studies, and two are awaiting classification. Four review authors independently extracted data, and two authors assessed the risk of bias. We calculated the mean difference (MD) with 95% confidence intervals (CI) for continuous outcomes and risk ratios (RR) with 95% confidence intervals for dichotomous outcomes. We assessed the quality of the evidence for each outcome using the GRADE approach.
We included two RCTs (212 participants), one of which was a cluster‐randomised trial. Adjusting for the design effect from clustering, reduced the total sample size to 210. Both studies were carried out in dental clinics and assessed ergonomic interventions in the physical domain, one by evaluating a multi‐faceted ergonomic intervention, which consisted of imparting knowledge and training about ergonomics, work station modification, training and surveying ergonomics at the work station, and a regular exercise program; the other by studying the effectiveness of two different types of instrument used for scaling in preventing WMSDs. We were unable to combine the results from the two studies because of the diversity of interventions and outcomes.
Physical ergonomic interventions. Based on one study, there is very low‐quality evidence that a multi‐faceted intervention has no clear effect on dentists' risk of WMSD in the thighs (RR 0.57, 95% CI 0.23 to 1.42; 102 participants), or feet (RR 0.64, 95% CI 0.29 to 1.41; 102 participants) when compared to no intervention over a six‐month period. Based on one study, there is low‐quality evidence of no clear difference in elbow pain (MD −0.14, 95% CI −0.39 to 0.11; 110 participants), or shoulder pain (MD −0.32, 95% CI −0.75 to 0.11; 110 participants) in participants who used light weight curettes with wider handles or heavier curettes with narrow handles for scaling over a 16‐week period.
Cognitive ergonomic interventions. We found no studies evaluating the effectiveness of cognitive ergonomic interventions.
Organisational ergonomic interventions. We found no studies evaluating the effectiveness of organisational ergonomic interventions.
There is very low‐quality evidence from one study showing that a multi‐faceted intervention has no clear effect on dentists' risk of WMSD in the thighs or feet when compared to no intervention over a six‐month period. This was a poorly conducted study with several shortcomings and errors in statistical analysis of data. There is low‐quality evidence from one study showing no clear difference in elbow pain or shoulder pain in participants using light weight, wider handled curettes or heavier and narrow handled curettes for scaling over a 16‐week period.
We did not find any studies evaluating the effectiveness of cognitive ergonomic interventions or organisational ergonomic interventions.
Our ability to draw definitive conclusions is restricted by the paucity of suitable studies available to us, and the high risk of bias of the studies that are available. This review highlights the need for well‐designed, conducted, and reported RCTs, with long‐term follow‐up that assess prevention strategies for WMSDs among dental care practitioners.
Priti Mulimani, Victor CW Hoe, Melanie J Hayes, Jose Joy Idiculla, Adinegara BL Abas, Laxminarayan Karanth
Plain language summary
Ergonomic interventions to prevent musculoskeletal disorders among dental care practitioners
What is the aim of this review?
Dental care providers are more prone to injuries and disorders of the bones, muscles, and joints, which are known as musculoskeletal disorders (MSDs), due to the physically and mentally stressful nature of their work. Various measures or solutions have been suggested to prevent work‐related MSDs (WMSDs). These are known as ergonomic interventions, which means harmonising things with which people interact, in order to meet people's needs, abilities, and limitations. Ergonomic interventions fall under physical, cognitive (mental), or organisational domains. The aim of this Cochrane Review was to find out if any of these ergonomic interventions were effective in preventing WMSDs among dental care practitioners. We collected and analysed all relevant studies to answer this question. We found two relevant studies.
There is very low‐quality evidence from one study, that a comprehensive ergonomics intervention, consisting of training, work station modification, and a regular exercise program has no effect on dentists' risk of WMSDs in the thighs or feet, over a period of six months. There is low‐quality evidence from one study that changing the tools used for scraping off dental plaque has no clear effect on dentists' elbow pain or shoulder pain over a four‐month period. Both included studies have several shortcomings, and did not follow‐up with participants for a sufficiently long period of time. We found no studies that evaluated the effectiveness of cognitive or organisational ergonomics interventions. We need better studies to evaluate the effectiveness of ergonomic interventions in dental care practitioners. It is very likely that including the results of new studies will change the conclusions of this review.
What was studied in the review?
Dental practitioners are highly susceptible to occupational hazards like MSDs, which have been attributed to deteriorating quality of life, burnout, and poor health, which often result in some practitioners quitting the profession. It has been suggested that introducing ergonomic interventions, by making improvements in working style, instruments used, dental office designs, physical activity, work posture, mental stress levels, appointment scheduling, or work environment may help to prevent WMSDs. Our review evaluated the effectiveness of all of these interventions in preventing WMSDs among those who practiced dentistry, be it dentists, dental hygienists, dental auxiliaries, dental nurses, or dental students. We assessed how well these measures prevented the occurrence of new WMSDs, not how they reduced the severity, or how they eliminated WMSDs that already existed. We evaluated the effectiveness of ergonomic interventions on the number of physician‐diagnosed WMSDs, self‐reported pain, or work ability.
What are the main results of the review?
We found two studies, involving 212 participants, that were conducted in dental practices or clinics in Iran and the United States. Both studies assessed physical ergonomic interventions. One study assessed a comprehensive ergonomics intervention, consisting of training, work station modification, and a regular exercise program, and the other study assessed two different types of instruments used for carrying out a dental procedure. The first study found that the comprehensive ergonomics intervention did not reduce musculoskeletal pain in the thighs or feet. The second study found that people using the two different kinds of tools for scraping off dental plaque had similar levels of elbow and shoulder pain. These studies had shortcomings, like poor methodology and short follow‐up times, hence we could not draw any definitive conclusions based on their findings.
We found no studies that assessed the effectiveness of cognitive or organisational ergonomics interventions. We need studies that are designed, conducted, and reported better to evaluate the effects of physical, cognitive, and organisational ergonomics interventions.
How up to date is this review?
We searched for studies published up to August 2018.
Priti Mulimani, Victor CW Hoe, Melanie J Hayes, Jose Joy Idiculla, Adinegara BL Abas, Laxminarayan Karanth
Implications for practice
Currently, there is insufficient evidence to conclude whether ergonomic interventions in the physical domain are effective in preventing musculoskeletal disorders among dental care practitioners.
There is very low‐quality evidence, provided by one study, indicating that a multi‐faceted ergonomic intervention has no clear effect on musculoskeletal pain in the thighs and feet.
There is low quality evidence, provided by another study, showing that changing instrument weight and handle size for scaling has no clear effect on pain in the elbows or shoulders.
Considering the methodological flaws and high risk of bias of the first study, and short follow‐up period and unclear risk of bias of the second study, we could not draw any reliable conclusions, or make recommendations for practice.
There is no evidence available to determine effectiveness of ergonomic interventions in the cognitive and organisational domains. Future studies will very likely affect the conclusions of this review.
Implications for research
Given that this review identified only two studies – one with high and another with unclear risk of bias – both of which assessed the effectiveness of physical ergonomics interventions, there is a clear need for high‐quality randomised controlled trials (RCTs) that examine the effectiveness of ergonomic interventions in all three ergonomics domains: physical, cognitive and organisational, in the prevention of work‐related musculoskeletal disorders (WMSDs) among dental care practitioners.
Participants. Future studies should have sufficient numbers of participants to detect statistically significant differences. Sample size determination for these trials should be based on Type 1 error (alpha value), adequate power (probability of correctly rejecting null hypothesis), and expected effect size acquired from previous literature. For example, to assess the prevalence of WMSD related to intervention effects would require a sample size of 369, at 5% width of a 95% confidence interval, assuming the expected prevalence was an average of 60%, based on values seen in the literature. To detect a 0.5 unit change in mean pain score with a standard deviation of 1.5, would need a total sample size of 284, with 142 for each arm of the study. As there are no trials of cognitive and organisational ergonomics interventions, researchers undertaking such studies may need to conduct initial pilot studies to acquire the effect size needed to estimate the final sample size for the larger parent projects.
From the outset, studies should be clear whether they are testing interventions for prevention or treatment. Prevention studies should recruit participants with minimum (not more than 25%, as a rough guideline) to no baseline MSD levels, and studies assessing treatment should include not less than 75% of participants with MSDs. As we explained in the background of our review, the occurrence of WMSDs in dental practitioners is a function of: gender, age, sitting or standing position of practice, posture, use of assistants, number of work hours per day, number of years worked, intensity of work done, force used, nature of procedures carried out, type of instruments, work‐rest cycles, office design, equipment used, organisational set‐up, stress, work environment, and pre‐disposing factors like weight, smoking, physical fitness, and pre‐existing systemic conditions. These participant attributes should be matched across experimental and control groups, in order to generate comparable and meaningful results. The best way to achieve this could be stratified randomisation, adjusting for stratification factors instead of simple randomisation. Conducting multiple‐centre studies, in both high‐ and low‐income countries, will further increase the usefulness of the findings.
Interventions. Instead of grouping interventions as an intervention unit, a better understanding of intervention effects could be obtained by assessing individual interventions over longer follow‐up times. We found no studies that assessed the effectiveness of cognitive or organisational interventions, and these need to be planned in the future. These must include trials to evaluate cognitive interventions such as: stress management and relaxation techniques, improving communication with co‐workers and patients, support systems to handle family‐work conflicts, training to master precision skills, prioritisation of operator preferences, role designation to increase job satisfaction, and organisational ergonomic interventions like: organisation of workflow, appointment scheduling, patient‐management system, pace and variety of workload, sequence and administration of procedures, taking breaks, stretching, exercising and mobilising after prolonged static posture, assistant support, task rotation, work‐rest cycles, and time management.
Comparisons. Interventions of the same domain, and within the domain, of similar types, should be compared with each other. For example, in the physical domain, comparisons can be made between interventions aimed at improving overall body posture or aimed at positioning and balance (such as appropriate use of patient and dentist chair, operatory design, workstation layout, dental operatory lighting, magnification devices, visual aids), or those targeting smaller and more intricate muscle groups (such as correct method of instrumentation and tool handling, changing the grip of hand‐held instruments, or instrument design factors). Within the cognitive domain, comparisons could be made between interventions aiming to provide relaxation, or between interventions aimed at improving social interactions and providing support systems, or between interventions aimed at improving precision skills. In the organisational domain, comparisons could be drawn between interventions aimed at streamlining organisation of workflow (such as appointment scheduling, patient‐handling system, time management), or between interventions aimed at mobilisation and rest during work (such as stretching, exercising and mobilising after prolonged static posture, or work‐rest cycles).
Outcomes. Objective measures to diagnose WMSDs are better than self‐assessments. Future studies might consider including independent medical examinations for diagnosis, or other institutional or workplace injury reporting systems as objective measures. Workers' compensation records can indicate number of hours lost due to WMSD, but it has to be borne in mind that not all workers may report WMSD or claim compensation for it, especially if they are self‐employed. We excluded many studies on ergonomic interventions, since they assessed surrogate outcomes, like grip strength, muscle activity, tactile discrimination, posture, tilt angle of body, neck and back extensions, or kinematics, instead of measuring the real clinical manifestation of a musculoskeletal disorder. A surrogate end point, or marker, has been defined as a laboratory measurement or physical sign that is used in therapeutic trials as a substitute for a clinically meaningful end point that is a direct measure of how a patient feels, functions, or survives, and that is expected to predict the effect of the therapy (Twadell 2009). Since surrogate outcomes do provide a good objective assessment of risk factors, it is important to first establish the validity of these outcome measures in predicting or representing the WMSD, through extensive research, and only then use them as authentic predictors of WMSDs. Until that time, we recommend that future studies use direct measurement of resulting WMSD, instead of measuring surrogate outcomes, to provide more meaningful results.
Appropriate randomisation methodology, with sequence generation, allocation concealment, and blinding should be executed and reported. The main risk for bias we identified in this review was blinding (performance and detection bias). Although blinding of participants and personnel (performance bias) is difficult to achieve for ergonomic interventions, researchers should consider minimising detection bias, by having independent, blinded assessors diagnosing upper limb and neck WMSDs. Trialists should also include objective measures to monitor compliance.