Relation between perceived and measured workload obtained by long-term inclinometry among dentists

Effect of a Novel Ergonomic Sheath on Dental Device-Related Muscle Work, Fatigue and Comfort-A Pilot Clinical Study

Background: Dental instrumentation with hand-held devices is associated with discomfort, fatigue and musculoskeletal diseases or repetitive stress injuries. The goal of this in vivo study was to determine the effect of an ergonomic handle sheath on muscle work, comfort and fatigue associated with (a) piezoelectric scaling by hygienists with and without musculoskeletal disorders (MSDs), and (b) dental cavity preparation by healthy dentists using a dental micromotor. Materials and Methods: Two groups of ten hygienists each tested the piezoelectric scaler. Hygienists in Group 1 had no MSDs, while those in Group 2 had been diagnosed with MSDs. Additionally, ten dentists with no MSDs used a dental micromotor to prepare four standardized cavities. Time-based work in four muscles, comfort and fatigue were recorded in the presence and absence of an add-on soft, insulating handle sheath. Data were analyzed using a repeated measures analysis of variance model with Tukey's post-hoc test. Results: Comfort, fatigue and muscle work were significantly better for both devices when the sheath was used. While hygienists with MSDs used more muscle work to complete the set scaling task, and the sheath-related reduction in work was somewhat greater, these MSD-related differences did not quite reach significance. Conclusions: The results of this pilot study show that the ergonomic performance of an ultrasonic scaler and a dental micromotor may be improved by the use of an ergonomic handle sheath.

Effect of a Novel Adaptive Handle Design on the Ergonomic Performance of Periodontal Curettes in Dental Hygienists with and without Musculoskeletal Disorders: A Pilot Clinical Study

(1) Background: Musculoskeletal disorders (MSDs), discomfort, fatigue, pain, and other acute and chronic work-related injuries are common among dental clinicians. Hand instruments constitute a primary risk factor for these conditions. The overall goal of this study was to compare in dental hygienists with healthy hands, and in those with MSDs, the effect of three different handle designs on instrumentation-related muscle work, comfort, fatigue, and quality of tactile feedback. (2) Methods: Clinicians tested three periodontal curettes: one with a novel adaptive silicone handle, another with a rigid resin handle, and the third with a rigid silicone handle. Ten hygienists-five with MSDs and five without-each scaled three typodonts using the three different curettes. Statistical analysis was performed using a General Linear Model (GLIM) and Tukey's post hoc test, and a significance level of p < 0.05 was implemented. (3) Results: On average, mean comfort and fatigue across all instruments were significantly worse in testers with MSDs, who also expended significantly more work to complete the same task. In all testers, a novel adaptive handle design was associated with significantly reduced total muscle work and post-instrumentation fatigue, as well as better comfort than conventional rigid handle designs. (4) Conclusions: An adaptive curette handle design demonstrated significantly better ergonomic outcomes than conventional rigid curette handle designs. Hygienists with MSDs expend significantly more muscle work during dental instrumentation.

A Novel Ergonomic Curette Design Reduces Dental Prophylaxis-Induced Muscle Work and Fatigue

BACKGROUND

To compare fatigue, comfort, and muscle work associated with the use of two periodontal curettes during scaling: one with a novel adaptive design, the other with a conventional non-adaptive design.

METHODS

Twelve hygienists scaled a typodont using two Universal Barnhart 5/6 curettes: (1) a prototype featuring an adaptive silicone-covered handle (Curette A), and (2) a stainless-steel curette (Curette B). Surface Electromyography (sEMG) traced muscle work. Hand positions, fatigue, comfort, pinch, and grasp strength were recorded. Paired t-tests and a repeated measures ANOVA with covariates were tested for differences. The significance level was set at p < 0.05.

RESULTS

Curette A performed significantly better in all categories. Pinch and grasp strength and fatigue were significantly reduced post-instrumentation for Curette B. Curette A required significantly less (i) total muscle work and (ii) work in individual muscles. Comfort, correct grasp, and blade adaptation were significantly better using Curette A.

CONCLUSIONS

A curette featuring a novel adaptive handle design demonstrated significantly improved ergonomic performance. Additional clinical studies are needed to solidify our understanding of the potential short- and long-term benefits of the novel curette handle design.

PRACTICAL IMPLICATIONS

A novel adaptive curette handle design that enables the clinician to adapt the instrument across the index finger may reduce musculoskeletal burden and fatigue, as well as improve comfort during periodontal instrumentation.

Wearable Motion Capture Devices for the Prevention of Work-Related Musculoskeletal Disorders in Ergonomics-An Overview of Current Applications, Challenges, and Future Opportunities

Work-related musculoskeletal disorders (WMSDs) are a major contributor to disability worldwide and substantial societal costs. The use of wearable motion capture instruments has a role in preventing WMSDs by contributing to improvements in exposure and risk assessment and potentially improved effectiveness in work technique training. Given the versatile potential for wearables, this article aims to provide an overview of their application related to the prevention of WMSDs of the trunk and upper limbs and discusses challenges for the technology to support prevention measures and future opportunities, including future research needs. The relevant literature was identified from a screening of recent systematic literature reviews and overviews, and more recent studies were identified by a literature search using the Web of Science platform. Wearable technology enables continuous measurements of multiple body segments of superior accuracy and precision compared to observational tools. The technology also enables real-time visualization of exposures, automatic analyses, and real-time feedback to the user. While miniaturization and improved usability and wearability can expand the use also to more occupational settings and increase use among occupational safety and health practitioners, several fundamental challenges remain to be resolved. The future opportunities of increased usage of wearable motion capture devices for the prevention of work-related musculoskeletal disorders may require more international collaborations for creating common standards for measurements, analyses, and exposure metrics, which can be related to epidemiologically based risk categories for work-related musculoskeletal disorders.

Mind the gap - development of conversion models between accelerometer- and IMU-based measurements of arm and trunk postures and movements in warehouse work

Sensor type (accelerometers only versus inertial measurement units, IMUs) and angular velocity computational method (inclination versus generalized velocity) have been shown to affect the measurements of arm and trunk movements. This study developed models for conversions between accelerometer and IMU measurements of arm and trunk inclination and between accelerometer and IMU measurements of inclination and generalized (arm) velocities. Full-workday recordings from accelerometers and IMUs of arm and trunk postures and movements from 38 warehouse workers were used to develop 4 angular (posture) and 24 angular velocity (movement) conversion models for the distributions of the data. A power function with one coefficient and one exponent was used, and it correlated well (r2 > 0.999) in all cases to the average curves comparing one measurement with another. These conversion models facilitate the comparison and merging of measurements of arm and trunk movements collected using the two sensor types and the two computational methods.

The Healing Environment of Dental Clinics through the Eyes of Patients and Healthcare Professionals: A Pilot Study

The physical environment of healthcare settings can promote both the healing process and patient feelings of well-being, as well as instill positive emotions in employees. The present study aimed to evaluate the dental work environment of a typical private and public dental clinic to identify key parameters that determine the perception of health facilities by patients and employees. The study was carried out from 1 to 20 December 2021, in two dental clinics in Ekaterinburg (Russian Federation) using 'ASPECT'. The participants were 58 staff and 94 patients. The results showed that, compared with patients, staff reported higher views scores, nature and outdoors scores, and comfort and control scores. The common criterion that distinguishes private clinics from public ones was comfort and control. Compared with patients in state clinics, patients in private clinics reported higher privacy, company and dignity scores, comfort and control scores, interior appearance scores, and facility scores. In general, while views scores and nature parameters can be singled out as a universal absolute value for everyone in a particular environment, staff pay more attention to factors that contribute to long-term comfortable stay and performance of their duties.

Ergonomics problems in dental profession-dentists working position

Background/Aim: Dental professionals are under higher risk of development musculoskeletal disorders. Working in unnatural position is one of the main risk factor for the development of MSDs. The aim of study was to record inclinations of the back in dentists during typically dental work. Material and Methods: In order to monitor the inclination of the body, high-performance sensor systems, triaxial digital 12-bit accelerometers LIS3LV02 (SGS-Thomson Microelectronics, USA) were installed. The inclination of the body was measured in ten dentists, while performing dental work. Results: During dental work in a sitting position, sloping back more than 20 ̊ was during 74% of the time, while during standing 62% of the time. The participants performed the dental examination sloping to the left side. During sitting, the inclination to the left side was greater than 20 ̊ during 65% of the time, while during work in the standing position it was 50%. Conclusions: An inclination of the back, more than 20 degrees is state as one of the main risk factor for the development of MSD. Inclination of the dentist's body in antero-posterior and medio-lateral direction during daily work in standing as well in sitting position was greater than 20 degrees. According to those facts dentists are under risk of developing musculoskeletal diseases during their daily working procedure. According to that ergonomics in dentistry is an area of research that needs more attention. The implementation of ergonomic principles in usual dental work leads to increased work performance, greater satisfaction, efficiency and productivity.

Ergonomics problems in dental profession-dentists working position

Background/Aim: Dental professionals are under higher risk of development musculoskeletal disorders. Working in unnatural position is one of the main risk factor for the development of MSDs. The aim of study was to record inclinations of the back in dentists during typically dental work. Material and Methods: In order to monitor the inclination of the body, high-performance sensor systems, triaxial digital 12-bit accelerometers LIS3LV02 (SGS-Thomson Microelectronics, USA) were installed. The inclination of the body was measured in ten dentists, while performing dental work. Results: During dental work in a sitting position, sloping back more than 20 ̊ was during 74% of the time, while during standing 62% of the time. The participants performed the dental examination sloping to the left side. During sitting, the inclination to the left side was greater than 20 ̊ during 65% of the time, while during work in the standing position it was 50%. Conclusions: An inclination of the back, more than 20 degrees is state as one of the main risk factor for the development of MSD. Inclination of the dentist's body in antero-posterior and medio-lateral direction during daily work in standing as well in sitting position was greater than 20 degrees. According to those facts dentists are under risk of developing musculoskeletal diseases during their daily working procedure. According to that ergonomics in dentistry is an area of research that needs more attention. The implementation of ergonomic principles in usual dental work leads to increased work performance, greater satisfaction, efficiency and productivity

Comparing the Structured Multidisciplinary work Evaluation Tool (SMET) questionnaire with technical measurements of physical workload in certified nursing assistants in a medical ward setting

The Certified Nursing Assistant (CNA) is an important part of the workforce in hospitals and nursing homes, whose work includes heavy and repetitive work tasks including patient manual handling. The Structured Multidisciplinary work Evaluation Tool (SMET) questionnaire is an Occupational Health Service method for evaluation of the work environment. The aim of this study is to compare the SMET questionnaire with technical measurements of physical workload in CNAs in a medical ward setting. 16 CNA's participated voluntarily to 8 h of measurements during one workday. Physical workload was measured with surface electromyography and inclinometers, and the work environment was evaluated with the SMET questionnaire during the same working day. Spearman's rho was used in the statistical correlation analysis between measurements. This study shows strong, statistically significant correlations between the items in the SMET questionnaire and measured physical workload, n CNAs.

Effects of Sensor Types and Angular Velocity Computational Methods in Field Measurements of Occupational Upper Arm and Trunk Postures and Movements

Accelerometer-based inclinometers have dominated kinematic measurements in previous field studies, while the use of inertial measurement units that additionally include gyroscopes is rapidly increasing. Recent laboratory studies suggest that these two sensor types and the two commonly used angular velocity computational methods may produce substantially different results. The aim of this study was, therefore, to evaluate the effects of sensor types and angular velocity computational methods on the measures of work postures and movements in a real occupational setting. Half-workday recordings of arm and trunk postures, and movements from 38 warehouse workers were compared using two sensor types: accelerometers versus accelerometers with gyroscopes-and using two angular velocity computational methods, i.e., inclination velocity versus generalized velocity. The results showed an overall small difference (<2° and value independent) for posture percentiles between the two sensor types, but substantial differences in movement percentiles both between the sensor types and between the angular computational methods. For example, the group mean of the 50th percentiles were for accelerometers: 71°/s (generalized velocity) and 33°/s (inclination velocity)-and for accelerometers with gyroscopes: 31°/s (generalized velocity) and 16°/s (inclination velocity). The significant effects of sensor types and angular computational methods on angular velocity measures in field work are important in inter-study comparisons and in comparisons to recommended threshold limit values.

Measurements and observations of movements at work for warehouse forklift truck operators

Inclinometry and video analyses can provide objective measures of physical workloads. The study aim was to measure and observe arm, back and head postures and movements among forklift truck operators (FLTOs) during a working day, analyzing differences between types of forklift trucks and to assess reported workload and health. Twenty-five male FLTOs in a high-level warehouse were randomly included. The data collected comprised technical measurements, video analyses of postures and movements, and a questionnaire measuring health, pain and workload. On average, the FLTOs rotated their head more than 45°, in total, 232 times/h. Video analysis revealed that FLTOs periodically drive the forklift truck sideways with the head rotated in the direction of travel, and in periods look upwards, in which the head is highly rotated and extended. Inclinometry and observations during the working day has the potential to be a valuable part of risk assessment promoting occupational safety and health.

Dentists working conditions - factors associated with perceived workload

BACKGROUND

Dentists are often exposed to occupational health hazards such as stress, high workload, and ergonomic and mental strain. However, there are limited studies focussing on occupational health and factors associated with working conditions. The aim of this study was to identify possible gender differences and factors associated with a high workload.

METHOD

The study population comprised of 187 dentists (123 women and 64 men) who had been working between 5 and 12 years. All participants completed a questionnaire regarding perceived workload and different working conditions. In the logistic regression analyses, gender and employment (employee or employer/manger), influence over work, social support, ergonomics, and working hours were used as independent covariates.

RESULTS

Poor satisfaction with ergonomic conditions and low influence on the work situation were reported by 40 and 47% of the participants, respectively. Female dentists were more often employees, reported lower influence over work situation, and more often worked part-time compared to male dentists. Those who reported a high workload significantly more often experienced that they had low influence over work, low levels of social support, and were not satisfied with ergonomic working conditions.

CONCLUSION

Dentists with low influence over work, low levels of social support, and who were unsatisfied with the ergonomic conditions reported higher levels of workload. The dentists experienced a similar workload, regardless of employment and gender. Preventive actions at the workplace in order to maintain a moderate workload promote both individual and organizational measures, to minimize the risk of poor occupational health.

Musculoskeletal Pain Survey Outcomes in Cleft Surgeons and Orthodontists

OBJECTIVE

Determine prevalence and characteristics of musculoskeletal pain and pathology in cleft providers.

DESIGN

An IRB-exempt survey based on previously validated surveys was administered. Data collected included demographics, practice description, musculoskeletal pain history, formal diagnoses, and interventions.

SETTING

Survey was sent to all cleft centers approved by the American Cleft Palate-Craniofacial Association worldwide.

PATIENTS, PARTICIPANTS

All cleft surgeons and orthodontists at these centers met entry criteria. Eighty-three providers responded. Cleft center coordinators were unable to confirm the number of survey recipients.

MAIN OUTCOME MEASURES

The hypothesis formulated prior to data collection was that prevalence would be comparable to general plastic surgeons and other at-risk health care providers.

RESULTS

Average age of respondents was 49.8 ± 11.3 years; 33.9% of respondents were female. Average body mass index was 24.8 ± 3.5 kg/m². Headaches were observed in 62.7% of surveyed respondents while musculoskeletal symptoms were reported in 89.8%. Of the 12 body parts addressed, most commonly affected were the neck (71.2%), shoulders (52.5%), and lower back (67.8%). Pain interfered with hobbies and home life in the majority of respondents (62.7%). Those who reported a formal diagnosis were more likely to undergo treatment including surgery (P < .01), medication (P = .03), and physical therapies (P < .01).

CONCLUSIONS

Cleft surgeons and orthodontists experience a higher frequency of headaches compared to the general population, and musculoskeletal disorders are more prevalent than reported by general plastic surgeons. Pain interferes with hobbies and home life. Formal diagnosis leads to treatment. Preventative exercises and interventions are presented.

Evaluation of biomechanical risk factors for neck and back disorders in traditional bakers during a work-day: Implications for ergonomics intervention

Awkward back and neck postures have been recognized as one common problem in bakery workers. This study aimed to evaluation of the biomechanical risk factors on the back and neck of bakers. Twenty bakers of four types of bread- baking systems were randomly selected. Working postures and movements of the back and neck during work were continuously recorded with inclinometry measurements during three hours. Physical workload in bakers was characterized by awkward postures and the percentage of time spent with the neck flexed more than 20°. Besides, low angular velocity and lack of postural variation during baking shows that bakers' back is in the static position and bakers have to work with constrained back for a long time. The current findings have important implications for prioritizing ergonomic interventions and any ergonomic interventions should be focused on reducing neck flexion and constrained postures of the back.

The Combination of Different Ergonomic Supports during Dental Procedures Reduces the Muscle Activity of the Neck and Shoulder

Ergonomic supports have become popular for the prevention of musculoskeletal disorders. This study sought to evaluate the efficacy of different ergonomic supports and their combination to reduce muscle activity of the neck and shoulder muscles. A one-way repeated measures design was used to evaluate 36 practicing dentists while they performed three posterior composite restoration procedures on a phantom head. Portable surface electromyography (sEMG) recordings were used to measure the muscle activity of three muscles (Upper Trapezius, Lateral Deltoid and Anterior Deltoid) in the dominant upper extremity, with and without the use of different ergonomic supports (ergonomic stool, magnification lenses and both) during the performance of these tasks. A repeated measures analysis of variance was used. The muscle activity of all muscles differed significantly across the four ergonomic conditions during the three tasks. The use of ergonomic supports such as magnification lenses, the ergonomic stool, or the combination of both, is effective for decreasing the muscle activity of the three muscles during the three tasks, when compared to standard practice. In addition, the decrease of muscle activity was higher using magnification lenses when compared to the ergonomic stool. Furthermore, the greatest decrease was found with the combination of both supports.

Trunk and upper arm postures in paper mill work

The aim of this study was to assess postures and movements of the trunk and upper arm during paper mill work, and to determine the extent to which they differ depending on method of assessment. For each of 28 paper mill workers, postures and movements were assessed during three full shifts using inclinometer registration and observation from video. Summary metrics for each shift, e.g., 10^th, 50^th, and 90^th posture percentile, were averaged across shifts and across workers. In addition, the standard deviation between workers, and the standard deviation between shifts within worker were computed. The results showed that trunk and arm postures during paper mill work were similar to other occupations involving manual materials handling, but the velocities of arm movements were lower. While postures determined by inclinometry and observation were similar on a group level, substantial differences were found between results obtained by the two methods for individual workers, particularly for extreme postures. Thus, measurements by either method on individuals or small groups should be interpreted with caution.

Effect of neck posture on cervicothoracic loads in overhead crane operators

Awkward neck postures are commonly documented to be associated with an increased risk of neck disorders. This study intended to continuously monitor and evaluate neck postures and to estimate the cervicothoracic loads among overhead crane operators during work time. Neck postures were measured among 40 randomly selected operators by an inclinometer during 2 h of work time. To determine the tasks and adapt the posture recordings to each of their corresponding tasks, direct observation was conducted concurrently. The median neck flexion and lateral bend angles were 28.23° and 11.30°, respectively. The mean compression and shear loads on the neck ranged from 75.22 to 113.14 N and from 9.50 to 41.11 N, respectively. The results indicated substantial levels of exposure to awkward and extreme neck postures among the operators. The nature of the operators' work and the visual requirements of some tasks will increase the mechanical loads on the neck.

Opting to wear prismatic spectacles was associated with reduced neck pain in dental personnel: a longitudinal cohort study

Background

The aim of this study was to investigate effects on perceived exertion, work ability self-reported neck pain and clinically diagnosed conditions in the neck, of an intervention with prismatic spectacles among dental personnel.

Methods

In this cohort study a baseline questionnaire including questions about frequency of neck pain, perceived exertion during work and background information was distributed to dental personnel in municipal dental care units. In connection, personnel from 78 out of 110 dental care units underwent a clinical neck examination and rated their perceived work ability with the single-item question from the Work Ability Index. The study population consisted of 564 participants; 366 in the questionnaire group, 321 in the examination group, whereof 123 participated in both assessments. In total 371 belonged to the intervention group and received individually adjusted prismatic spectacles after the baseline assessments (inclusion based on self-selection) and 193 belonged to the reference group. At the 12-month follow-up the clinical examination was repeated and the same questionnaire with additional questions was completed. Fisher’s exact test or the Mann–Whitney U test was used to assess differences between the intervention group and the reference group at baseline. Differences at follow up between the two groups were assessed by means of Linear-by Linear association test for trends.

Results

A significant decrease in neck pain (p = 0.047), clinical diagnoses in the neck (p = 0.025), and perceived exertion (p = 0.003) was observed at follow up for the intervention group compared to the reference group. Moreover, for the intervention group a significantly improved self-rated work ability (p = 0.040) was reported. Finally, opting to wear prismatic spectacles during dental work appeared to have a preventive effect on neck pain.

Conclusions

Dental personnel opting to wear prismatic spectacles reduced their neck pain significantly more at follow up compared with the reference group. These results are worthwhile testing in a randomised design. The practical implication of this study is that recommendations regarding ergonomics for dental professionals may include the use of prismatic glasses, both as primary and secondary prevention of work-related neck pain. Such glasses should also be tested in other working situations where the work tasks include high visual demands in sustained awkward neck postures.

Electronic supplementary material

The online version of this article (doi:10.1186/s12891-016-1145-1) contains supplementary material, which is available to authorized users.

Working postures and physical activity among registered nurses

Nurses report a high prevalence of musculoskeletal discomfort, particularly of the low back and neck/shoulder. This study characterized the full-shift upper arm and trunk postures and movement velocities of registered nurses using inertial measurement units (IMUs). Intensity of occupational physical activity (PA) was also ascertained using a waist-worn PA monitor and using the raw acceleration data from each IMU. Results indicated that nurses spent a relatively small proportion of their work time with the arms or trunk in extreme postures, but had few opportunities for rest and recovery in comparison to several other occupational groups. Comparisons between nurses in different PA groups suggested that using a combination of accelerometers secured to several body locations may provide more representative estimates of physical demands than a single, waist-worn PA monitor. The findings indicate a need for continued field-based research with larger sample sizes to facilitate the development of maximally effective intervention strategies.

The relationship between physical load and musculoskeletal complaints among Brazilian dentists

The aim of the present study was to assess the relationship between physical load and musculoskeletal complaints in dentistry and to analyze the prevalence and severity of such complaints in nine anatomical regions using a cross-sectional study of 387 dentists from Natal, Brazil. The highest prevalence of complaints was related to the lower back (58.4%) and the lowest prevalence was found in the elbow (10.3%). In general, symptoms were classified as mild because they did not cause absence due to illness. Pain complaints were associated with the following characteristics: awkward posture at work; prolonged standing or sitting; strenuous position of the upper limbs; excessive tightening of the hands during clinical treatment; and the use of vibrating tools. The results of the present study suggest a high prevalence of musculoskeletal complaints in dentists that are significantly associated with variables related to their physical workload.

Continuous assessment of back and upper arm postures by long-term inclinometry in carpet weavers

Awkward back and shoulder postures have been suggested to be a cause of back and shoulder discomfort in carpet weavers. This study aimed at continuous assessment of the upper arm and back postures and estimation of biomechanical load subtasks using inclinometers during 4 h. Median of trunk flexion angle in weavers was 18° and 13° during knotting and compacting subtasks, respectively. The weavers worked with arms elevated greater than 45° for %4.5 of the work time. The average cumulative compression load for males and females were estimated at 22 MN-S and 13 MN-S, respectively. In addition to poor workstation design, constrained posture of the trunk and low elevation and velocity for both arms may be the main risk factors for developing fatigue and disorders in the back and shoulder regions among carpet weavers. Therefore, any ergonomic interventions should be focused on reducing trunk flexion and the constrained postures of weavers.

Working conditions, health and productivity among dentists in Swedish public dental care--a prospective study during a 5-year period of rationalisation

In recent decades, comprehensive rationalisations have been implemented in public dentistry in Sweden. How rationalisations affect working conditions, health and production from a long-term perspective has been poorly investigated. This study aims to analyse changes and associations in dentists' working conditions, health and productivity during a 5-year period. In 2003 and 2008, 65 dentists responded to questionnaires measuring work conditions and health. Treatment times for patients and productivity were tracked in electronic registers. Paired t-tests showed that the number of treated adult patients per dentist increased, and perceived physical working conditions improved while perceived work control and leadership deteriorated. Structural equation modelling showed that physical factors were important for health and productivity. When assessing risks in the work environment, there is a need to understand the interaction of effects on working conditions and health due to rationalisations so as to increase the sustainability of production systems.

PRACTITIONER SUMMARY

Dentistry in Sweden has undergone considerable change. Questionnaire surveys with dentists, undertaken in 2003 and 2008, found that the present rationalisations resulted in improved perceived physical working conditions. Aspects of the psychosocial working environment had deteriorated, however. This is a concern as health and workability are important for workplace efficiency.

Physical workload in neck, shoulders and wrists/hands in dental hygienists during a work-day

Physical workload was recorded by electromyography, inclinometry and goniometry for twelve female dental hygienists during authentic work. Their work was, in relation to other types of work, characterised by pronounced head flexion (90th percentile 46°), high loads on the forearm extensor muscles (90th percentile 23% and 18% of maximal EMG (MVE), for the right and left sides, respectively), average loads on trapezius muscles (90th percentile 15% and 14% MVE), average arm elevation (99th percentile 83° and 72°) and average wrist flexion and velocities (50th percentiles 17° of extension and 7.3°/s, for the right side). Manual scaling and machinery (use of ultrasonic scaling and hand-pieces) showed higher loads on the trapezius muscles, regarding muscular rest, as well as the 10th and 50th percentiles, than the other tasks, and for the forearm extensor muscles, an almost complete lack of muscular rest (0.1% time), and much higher loads regarding the 10th and 50th percentiles. Further, more pronounced head flexion and lower head and upper arm velocities were found, indicating more constrained postures for the neck and shoulders for the manual scaling and machinery. Use of ultrasonic scaler reduced the 50th percentile loads on the right forearm extensor muscles, but had no effect on the fraction of muscular rest and on the 10th percentile load. These findings are consistent with the high prevalences of musculoskeletal disorders among dental hygienists.

Full shift arm inclinometry among dairy parlor workers: a feasibility study in a challenging work environment

Over the last 20 years, the US dairy industry has experienced a significant transformation from small farm operations to an industrialization of the milking process. This transformation has resulted in improvements in process efficiency and product quality. Milking tasks in large-herd parlors are highly-repetitive involving awkward postures and high muscle loads of the upper extremity. Field-based direct measures of physical exposures have been limited in challenging work settings such as dairies. This study evaluated full-shift exposures of posture and motion of the upper extremity among large-herd parlor milkers using wireless inclinometry. Results suggest large-herd parlor workers may be exposed to high exposure levels (posture, movement velocity, repetition, and inadequate rest) associated with the development of shoulder pathology. Compared to other high-risk occupations involving shoulder-intensive work, parlor workers may have higher exposure levels. These findings warrant the need for continued field-based research with larger sample sizes to facilitate the development of cost-effective intervention strategies.

Wrist activity monitor counts are correlated with dynamic but not static assessments of arm elevation exposure made with a triaxial accelerometer

There is evidence in the literature of a link between workplace arm elevation exposure and atraumatic shoulder injuries. However, there are several methods that can be used to assess this exposure. The goal of the present study was to compare the outcomes of an activity monitor attached to the wrist and a triaxial accelerometer mounted on the humerus. Twenty-one workers wore both sensors over the course of a full workday. While the activity monitor data was not significantly correlated with any static humeral parameters, it was strongly correlated with all dynamic parameters. The use of a simple, commercially available activity monitor might offer an inexpensive alternative for the assessment of a large number of subjects over multiple workdays to determine the relationship between dynamic motion and occupation shoulder injuries in the future.

PRACTITIONER SUMMARY

Arm overuse has been linked to occupation-related shoulder injuries. An activity monitor attached to the wrist and a triaxial accelerometer mounted on the humerus were compared in a field trial. The results demonstrate that, under certain conditions, a commercially available activity monitor might be a useful tool for exposure assessment.

Bias and imprecision in posture percentile variables estimated from short exposure samples

Background

Upper arm postures are believed to be an important risk determinant for musculoskeletal disorder development in the neck and shoulders. The 10^th and 90^th percentiles of the angular elevation distribution have been reported in many studies as measures of neutral and extreme postural exposures, and variation has been quantified by the 10^th-90^th percentile range. Further, the 50^th percentile is commonly reported as a measure of "average" exposure. These four variables have been estimated using samples of observed or directly measured postures, typically using sampling durations between 5 and 120 min.

Methods

The present study examined the statistical properties of estimated full-shift values of the 10^th, 50^th and 90^th percentile and the 10^th-90^th percentile range of right upper arm elevation obtained from samples of seven different durations, ranging from 5 to 240 min. The sampling strategies were realized by simulation, using a parent data set of 73 full-shift, continuous inclinometer recordings among hairdressers. For each shift, sampling duration and exposure variable, the mean, standard deviation and sample dispersion limits (2.5% and 97.5%) of all possible sample estimates obtained at one minute intervals were calculated and compared to the true full-shift exposure value.

Results

Estimates of the 10^th percentile proved to be upward biased with limited sampling, and those of the 90^th percentile and the percentile range, downward biased. The 50^th percentile was also slightly upwards biased. For all variables, bias was more severe with shorter sampling durations, and it correlated significantly with the true full-shift value for the 10^th and 90^th percentiles and the percentile range. As expected, shorter samples led to decreased precision of the estimate; sample standard deviations correlated strongly with true full-shift exposure values.

Conclusions

The documented risk of pronounced bias and low precision of percentile estimates obtained from short posture samples presents a concern in ergonomics research and practice, and suggests that alternative, unbiased exposure variables should be considered if data collection resources are restricted.

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

AIM

To quantify the effects of using prismatic glasses including optometric correction, on head and neck kinematics, perceived exertion and comfort, during work in the oral cavity.

METHODS

The study population consisted of forty-five participants. After a basic ergonomic education, baseline measurements of head and neck kinematics were made using inclinometers. Perceived exertion and comfort were rated by the participants. An intervention group (n = 25), selected at random from the participants, received prismatic glasses and optometric correction when needed and were compared with a control group (n = 20). Follow up assessments were made after the intervention.

RESULTS

At follow up there was a reduction in both the intervention group (8.7°) and in the control group (3.6°) regarding head flexion. Neck flexion was reduced by 8.2° in the intervention group and 3.3° in the control group. The difference between the intervention and the control groups, i.e. the effect of the intervention, was statistically significant for both head (5.1°; p = 0.009) and neck (4.9°; p = 0.045) flexion. No effect of the intervention was seen regarding perceived exertion and comfort.

CONCLUSION

The reduction in head and neck flexion achieved by the prismatic glasses is likely to reduce the risk of neck pain during dental work. The effect of the prismatic lenses could not be separated from the effect of the optometric correction. The possible effect of the ergonomic education was not evaluated.

Mechanical exposure among general practice dentists in Sweden and possible implications of rationalisation

The present study investigates the dental work in terms of time distribution and mechanical exposure in value-adding work (VAW) and non-VAW. Further rationalisation of dental work would typically involve an increase in the proportion of VAW. Information on mechanical exposure within the classes of VAW and non-VAW may be used to predict possible implications of rationalisation. Sixteen dentists were investigated. Using a data logger, postures and movements were continuously recorded for each subject during the 4 h of work, which included the 45 min of video recording. Time distribution and mechanical exposure for the six different work activities identified were evaluated from the video recordings, using a loss analysis technique. VAW, which comprised 54% of the total working time, generally implied significantly more constrained mechanical exposures as compared with non-VAW. The results suggest that future rationalisation of dental work, involving a reduction of non-VAW, may increase the risk of developing musculoskeletal disorders. Statement of Relevance: The present study illustrates the potential effects of rationalisation on biomechanical exposures for dentists. The results highlight the significance of integrating ergonomic issues into the rationalisation process in dentistry in addition to ordinary workstation and tool design improvements performed by ergonomists.

A review of direct neck measurement in occupational settings

No guidelines are available to orient researchers on the availability and applications of equipment and sensors for recording precise neck movements in occupational settings. In this study reports on direct measurements of neck movements in the workplace were reviewed. Using relevant keywords two independent reviewers searched for eligible studies in the following databases: Cinahal, Cochrane, Embase, Lilacs, PubMed, MEDLINE, PEDro, Scopus and Web of Science. After applying the inclusion criteria, 13 articles on direct neck measurements in occupational settings were retrieved from among 33,666 initial titles. These studies were then methodologically evaluated according to their design characteristics, exposure and outcome assessment, and statistical analysis. The results showed that in most of the studies the three axes of neck movement (flexion-extension, lateral flexion and rotation) were not simultaneously recorded. Deficiencies in available equipment explain this flaw, demonstrating that sensors and systems need to be improved so that a true understanding of real occupational exposure can be achieved. Further studies are also needed to assess neck movement in those who perform heavy-duty work, such as nurses and electricians, since no report about such jobs was identified.