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Work 56 (2017) 617–623 DOI:10.3233/WOR-172524 IOS Press
Work-related musculoskeletal disorders among Jordanian dental technicians: Prevalence and associated factors Zeid Al-Hourania,∗ , Mohammad Nazzalb , Yousef Khaderc , Khader Almhdawib and Abdel Rahim Bibarsa a Department
of Applied Dental Science, Faculty of Applied Medical Sciences, Jordan University of Science and Technology, Irbid, Jordan b Department of Rehabilitation Sciences, Faculty of Applied Medical Sciences, Jordan University of Science and Technology, Irbid, Jordan c Department of Public Health, Community Medicine, and Family Medicine, Faculty of Medicine, Jordan University of Science and Technology, Irbid, Jordan Received 17 August 2015 Accepted 20 October 2016
Abstract. BACKGROUND: Dental technology is a profession that requires precise manual skills and dexterous handling of small tools. There is an abundance research on work-related musculoskeletal disorders (WMSDs) affecting dentists, dental hygienists and dental assistants, yet very few articles investigated WMSDs among dental technicians. OBJECTIVES: This study aimed to determine the prevalence of WMSDs among Jordanian dental technicians and their associated factors. METHODS: A cross-sectional design was conducted. A sample of Jordanian dental technicians (n = 81) were asked to complete a validated structured self-administrated questionnaire to measure WMSDs and its associated factors. RESULTS: A sample of 81 dental technicians completed the survey (50.6% younger than 30 years, 61.7 were males). Pain complains were significantly higher in female, younger technicians, and with increased workload. All participants reported WMSDs in at least one body part in the last 12 months. The most common pain areas reported were in the neck (70.4%) and shoulders (71.6%). CONCLUSION: This study found a high prevalence of musculoskeletal complaints in dental technicians. Future studies are indicated to investigate the actual mechanisms causing WMSDs among dental technicians. Keywords: Dental technology, dental technician, occupational health, work-related musculoskeletal disorders
1. Introduction
∗ Address for correspondence: Dr. Zeid Al-Hourani, Department of Applied Dental Sciences, Faculty of Applied Medical Sciences, Jordan University of Science and Technology, PO Box 3030, Irbid 22110, Jordan. Tel.: +962 2720 1000 26885; Fax: +962 7201087; E-mail: [email protected].
Work-related musculoskeletal disorders (WMSDs) are common disorders affecting professionals working in dentistry related professions [1]. Common symptoms of WMSDs including fatigue, discomfort, limited ability of movement, and pain in joints, muscles, and tendons [2]. WMSDs are mostly
1051-9815/17/$35.00 © 2017 – IOS Press and the authors. All rights reserved
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associated with work patterns or using vibrating tools that include fixed or constrained body positions; such as repetitive movements, less resting period during breaks and concentrated force/movement on specific parts of the body, such as the back, neck, hand, or wrist [3–6]. Therefore, WRMDs might vary between professionals due to variability of the physical requirement of each profession. WMSDs are relatively common among dental professionals. Pain complaints are associated with abnormal or sustained prolonged posture during sitting or standing, strenuous position of the upper limbs, excessive tightening of hands and the use of vibrating tools [7]. There is extensive literature on the prevalence of WRMDs and its contributing factors to dentists, [7–11] dental hygienists [12] and dental assistants [13]; yet very few articles investigated WMSDs among Dental Technicians (DTs) [5, 14]. The nature of DTs’ work is different than of other dental professions. DTs also are exposed to mechanical vibrating forces produced by dental equipment such as the rotary hand-piece, wax knife, carvers and mixing bowls. Moreover their work requires the artistic aptitude for details and precision to fabricate various dental prostheses [15]. The Extensive use of tools is a well-known contributor to many upper extremity disorders [16]; peripheral nerve entrapment (e.g. median and ulnar nerve) is a common disorder acquired by the excessive vibrations of these tools [13]. DTs work requires high repetition and precision of hand movements, back and neck sustained flexion, and fixed upper extremity positioning [14]. Furthermore, a study conducted in Malaysia showed that the prevalence of back pain among all dental personnel was 44.4%; among those with the highest prevalence were DTs (52.4%) mainly due to poor posture [17]. This study was specific to low back and included heterogeneous sample of dental professionals without highlighting the associated factors to WMSDs among DTs. To the best of our knowledge, there is no study that specifically investigated the prevalence of WMSDs and its associated factors and impact on work performance among DTs. Therefore, the main aim of the study was to estimate the prevalence of WMSDs among DTs. Secondly, to identify personal and workrelated factors that are associated with occurrence of WMSDs for each body region. Finally, it aimed to study the work limitation due to WMSDs. In summary, estimating the prevalence and outlying the jobrelated factors of WMSDs among DTs would contribute to establishing awareness among practitioners,
developing precautions and preventive strategies as well as maximizing job satisfaction and efficiency.
2. Methods 2.1. Study design and study population A cross-sectional design was used. Cross-sectional design is the design of choice for surveying a prevalence of a certain topic in a population at one time [18]. Data was collected between November 2013 and March 2014. DTs with at least one year of employment in dental laboratories in all health sectors in the Middle and the Northern part of Jordan were included. Technicians with systemic disorders, history of musculoskeletal trauma, and pregnant women were excluded. In Jordan, there is estimated 300registered DTs. Among those technicians, around one hundred technicians who met the criteria were approached. The response rate was 81%. 2.2. Data collection procedure Data collection was conducted by trained research assistant (occupational therapist) who approached the eligible DTs in their offices. This study has been conducted in full accordance with the World Medical Association Declaration of Helsinki [19] and approved by the Jordan University of Science and Technology ethical committee board and the institutional review board. Technicians consented verbally to participate after full explanation of the study. The technicians were asked to complete a validated structured self-administrated questionnaire. The research assistant was available for any inquiry. 2.3. Instrument The questionnaire had two major sections. The first section was to collect relevant socio-demographic and work-related data. Socio-economic data collected were age, gender, and level of education. Work-related data collected were years of experience, number of working days per week, number of working hours per day, and work sector (governmental versus private). In addition, the questionnaire included some other questions related to rest breaks, length of rest break, job description (administrative versus technician), as well as, daily physical activities. This section was developed through intensive literature review and series of discussion among the
Z. Al-Hourani et al. / Work-related musculoskeletal disorders among Jordanian
research team members and expert DTs to ensure the validity of its content. This section consisted mainly of yes/no response format as well as a 5-point Likert scale format [20]. This first section was validated on a group of 8 DTs to ensure its comprehensibility. No changes were done on the questionnaire because all items were clearly understood by participants (those were not included in the analysis). The second section included an Arabic version of the Nordic musculoskeletal questionnaire [21] which was cross-culturally translated and adapted into Arabic for the purpose of using it in this study by MN (unpublished). The Nordic questionnaire is used to detect acute and chronic musculoskeletal complaints in the neck, shoulders and upper extremities, upper and lower back, thighs and lower extremities [22]. Its validation included both forward and backward translation. An expert committee then confirmed the final version. It was then conducted twice on a number of 40 individuals, 24 hours apart. The new adapted Nordic questionnaire was reported to have very good test-retest reliability as evidenced by kappa coefficient values ranging from 0.88 to 1.
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Table 1 The socio-demographic and job related characteristics of participants Variable Gender Males Females Age 15 years Working days 4-5 day 6-7 days Working hours ≤7 hours >7 hours Work sector Governmental Private
n
%
50 31
61.7 38.3
41 40
50.6 49.4
35 46
43.2 56.8
64 17
79.0 21.0
38 43
46.9 53.1
25 56
30.9 69.1
41 40
50.6 49.4
The socio-demographic and job related characteristics of participants are shown in Table 1.
2.4. Statistical analysis 3.2. Prevalence rates of musculoskeletal pain Data were analyzed using the Statistical Package for Social Sciences software, SPSS (SPSS Inc., Chicago, IL, USA) version 16 (16 SPSS Inc. 2007. SPSS for Windows, Version 16.0. Chicago, SPSS Inc). Percentages were used to describe categorical variables. The differences in prevalence rates were tested using chi-square test. Multivariate logistic regression analyses were performed to determine the factors associated with musculoskeletal disorders in each body part. A p-value of less than 0.05 was considered statistically significant.
3. Results 3.1. Participants’ characteristics This study included a total 81 DTs (50 males and 31 females). Almost half of them (50.6%) were younger than 30 years old. Less than half of the participants (43.2%) had a diploma education and 56.8% had a bachelor or higher degree education. Furthermore, almost 79.0% of the participants had experience less than 15 years, and more than half of the participants (53.1%) work 6-7 days a week; In addition 69.1% of the participants work for more than 7 hours per day.
Table 2 shows the prevalence of musculoskeletal disorders among DTs in each part of the body. All participants had at least one musculoskeletal disorder in a body part during the last 12 months. The most common musculoskeletal pain was found to be in the neck (70.4%) and shoulders (71.6%). About two thirds of the participants reported upper (65.0%) and/or lower back (66.3%) pain during the last 12 months. Work limitation due to musculoskeletal pain was reported by 46.6% to 63.2% of the participants. However, work limitations due to WMDs were more common in the elbow (56.3%), the lower back (62.3%) and the hip (63.2%). Moreover, musculoskeletal pain during the last 7 days was mostly common in the neck (50.5%), shoulders (53.8%), upper back (59.0%) and low back (56.0) body parts. The prevalence of musculoskeletal pain during the last 12 months according to socio-demographical and job-related characteristics is shown in Table 3. Musculoskeletal pain in the neck, shoulder and wrist were associated with at least one participant characteristic. Neck pain was reported in those who are younger than 30 years in comparison to the elder (80.5% Vs 60.0%). Shoulder pain was reported more by females compared to males (90.3% Vs 60%) whereas wrist
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Z. Al-Hourani et al. / Work-related musculoskeletal disorders among Jordanian Table 2 Prevalence rates musculoskeletal disorders in different body parts in dental technicians Body part
Neck Shoulder Elbow Wrist Upper back Lower back Hip Knee Ankle
Musculoskeletal pain in the last 12 months n % 57 58 16 38 52 53 19 31 26
Work limitation due to musculoskeletal pain n %
70.4 71.6 20.3 48.1 65.0 66.3 24.1 38.3 32.9
27 27 9 19 26 33 12 16 13
Musculoskeletal pain in the last 7 days n %
47.4 46.6 56.3 50.0 50.0 62.3 63.2 51.6 50.0
40 42 10 30 46 44 12 25 24
50.0 53.8 12.7 38.5 59.0 56.4 15.2 32.1 30.4
Table 3 The prevalence rates of musculoskeletal pain in the last 12 months according to socio-demographical and job-related characteristics Neck n (%) Gender Male 32 (64.0) Female 25 (80.6) Age 15 years 5 (29.4) Working Days/week 4-5 days 29 (76.3) 6-7 days 28 (65.1) Working Hours/Day ≤7 days 17 (68.0) >7 days 40 (71.4)
Shoulder n (%)
Elbow n (%)
Wrist n (%)
Upper Back n (%)
Lower Back n (%)
Hip n (%)
Knee n (%)
Ankle n (%)
30 (60.0)∗ 28 (90.3)
10 (20.0) 6 (20.7)
17 (34.0)∗ 21 (72.4)
31 (63.3) 21 (67.7)
34 (68.0) 19 (63.3)
13 (26.0) 6 (20.7)
19 (38.0) 12 (38.7)
16 (32.0) 10 (34.5)
33 (80.5) 25 (62.5)
10 (24.4) 6 (15.8)
25 (61.0)∗ 13 (34.2)
27 (67.5) 25 (62.5)
26 (65.0) 27 (67.5)
10 (24.4) 9 (23.7)
14 (34.1) 17 (42.5)
14 (34.1) 12 (31.6)
23 (65.7) 35 (76.1)
3 (9.1) 13 (28.3)
8 (24.2)∗ 30 (65.2)
24 (68.6) 28 (62.2)
27 (77.1) 26 (57.8)
10 (30.3) 9 (19.6)
16 (45.7) 15 (32.6)
13 (39.4) 13 (28.3)
46 (71.9) 12 (70.6)
14 (22.6) 2 (11.8)
35 (56.5)∗ 3 (17.6)
42 (66.7) 10 (58.8)
39 (61.9) 14 (82.4)
15 (24.2) 4 (23.5)
22 (34.4) 9 (52.9)
22 (35.5) 4 (23.5)
30 (78.9) 28 (65.1)
10 (26.3) 6 (14.6)
26 (68.4)∗ 12 (29.3)
24 (64.9) 28 (65.1)
22 (59.5) 31 (72.1)
9 (23.7) 10 (24.4)
14 (36.8) 17 (39.5)
15 (39.5) 11 (26.8)
21 (84.0) 37 (66.1)
5 (21.7) 11 (19.6)
9 (39.1) 29 (51.8)
14 (56.0) 38 (69.1)
13 (52.0) 40 (72.7)
7 (30.4) 12 (21.4)
8 (32.0) 23 (41.1)
8 (34.8) 18 (32.1)
∗ p-vale < 0.05.
pain was significantly more common in women, subjects less than 30 years old, those with a bachelor degree or higher, subjects with ≤15 years of experience and among those who reported working of 4-5days/week. 3.3. Multivariate analysis of factors associated with musculoskeletal pain The multivariate analysis of factors associated with musculoskeletal disorders (Table 4) showed that the factors that were significantly associated with musculoskeletal disorders in at least one body part were age, gender, education, and daily working hours. Elder participants were less likely to report neck pain (OR = 0.4). Females were almost 6 times (OR = 6.2) more likely to report shoulder pain than males.
Bachelor or higher education was associated with increased odds of elbow pain. Females (OR = 7.7), bachelor or higher education (OR = 8.3), working hours >7 hours/day (OR = 7.7) were significantly associated with increased risk of developing wrist pain. None of the studied characteristics was associated with musculoskeletal pain in any other body parts.
4. Discussion Studies that examined the WMSDs among DTs in terms of prevalence and its associated factors are scarce [2]. This is the first study to provide the prevalence of WMSDs among DTs and their associated factors. Consistent with the existing literature
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Table 4 Multivariate analysis of factors associated with musculoskeletal pain for each of body part as response variable Neck pain Age (≥30 vs. 7 hours vs. ≤7 hours)
[5, 7, 23], this study showed that the profession of dental technicians is associated with a high rate of WMSDs. This study highlighted the WMSDs among DTs using Nordic Musculoskeletal questionnaire, the most prevalent WMSDs were in neck, shoulder, upper back and lower back. The most relevant contributed factors to WMSDs among DTs were, age, gender, education, and daily working hours. Despite all of our participants being healthy individuals, every single one complained of work-related pain in at least one body part during the last 12 months. In this study the most common pain sites were in the neck (70.4%), shoulders (71.6%) and lower back (66.3%). This is consistent with previous studies on health workers and dental professions WMSDs [24, 25]. In dental professions, neck and lower back pain are highly associated with working postures that may exert high pressure on intervertebral disk as well as prolonged spinal hypomobility [26]. Furthermore, increased biomechanical stress is consideed as a risk factor that might lead to spine and/or nerve roots degenerative changes and subsequent related pain [13, 27]. Nevertheless, back pain has been found to be a major occupational health hazard also in other dental professions [13]. Neck pain was most common in DTs younger than 30 years old. Around 79% of the participants have had a work experience of less than 15 years which might indicate inefficient work skills or habits/patterns due to lack of experience. In addition, some argue that older population have an increased pain tolerance or adapt better to pain compared to younger population [28, 29]. Consistant with the literature, younger dentists have a higher frequency of musculoskeletal pain and discomfort than older colleagues [30]. In this study, wrist and shoulder pain were significantly higher in female as compared to male. Carpal tunnel syndrome is more prevalent in dental
OR (95% confidence interval)
P-value
0.4 (0.1, 1.0)
0.047
6.2 (1.7, 23.3)
0.007
4.8 (1.2, 19.8)
0.028
7.1 (1.9, 26.8) 8.3 (2.3, 30.9) 7.7 (1.9, 31.2)
0.004 0.001 0.004
professionals, especially in women [27, 31, 32]. It is well documented that certain WMSDs are more common among female dental professionals. For example, a study demonstrated higher prevalence of neck pain among female dentists as compared to males [30]. Other studies reported that wrist and hand pain including CTS are most common among female dental professional [33, 34]. The differences among genders still remain unknown; yet some studies suggest that females might have higher sensitivity to pain and therefore usually report more pain complains than males [35, 36]. Moreover, other studies suggests that females usually show substantially higher muscular activity in relation to their capacity, making them more prone to exertion and eventually hurting their muscles and joints more [37]. Synthasizing these studies results might explain the increased levels of pain among female DTs when compared to male colleagues. The workload of the participants is considered a heavy and a demanding workload. Around 53% of participants work 6 or more days per week and around 69% of our participants work 7 or more hours per day. Being a DT in Jordan requires generally to work long hours considering that most of the DT laboratories are owned and operated by private bussinesses whose major concern is profit. Many of these bussinesses employ cost-effective strategies that demand employees to produce as maximum dental prosthesis as possible in less time as possible. This forces DTs to carryout repetitive tasks in repetitive or static postures [1]. It is well documented that repetitive stress could result in repetitive trauma which could explain the high WMSDs among our participants. The presented data showed that increased working load of participating DTs (working hours >7 hours/day) was significantly associated with wrist pain. This is consistent with the WMSDs research
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among other dental health professionals revealing high association between WMSDs affecting upper extremities and high workload [38, 39]. Generally, as job requirements increase, most musculoskeletal symptoms also increase [40]. Furthermore, longer exposures to awkward postures might lead to increased musculoskeletal complains [41]. Previous studies on DTs have not discussed high prevalence of wrist pain yet it might be common among DTs due to the repetitive precise nature of their work using rotary instruments and carrying out finishing and polishing procedures for various dental prosthesis fabricated in the dental laboratory [14]. 5. Clinical implications Specific studies on effective interventions to prevent or treat WMSDs among DTs lack in the literature. DTs are generally advised to adhere to recommendations obtained from other dental professions and general population studies. There are many suggested conservative interventions available for other dental professions to reduce the effects of WMSDs [42]. These interventions can be categorized into physiotherapy and exercises, ergonomics, behavioral modifications and other interventions [6]. Using proper ergonomic tools, taking enough breaks, reducing working load are few suggestions to reduce WMSDs among DTs [6, 43, 44]. This study reported that certain DT categories are more prone to WMSDs than others. Female and young DTs are advised to take more precautions to avoid potential WMSDs especially those of wrist and neck. In general, there should be a focus on prevention rather than remedy. Education workshops on proper ergonomics in the workplace can be pivotal in reversing this phenomenon among DTs especially among the more prone category; female and young DTs.
work in dental technology is not expected to be significantly different across countries since technician’s manual procedures fabricating dental prostheses are similar. 7. Conclusions This study concluded a high prevalence of musculoskeletal complaints among DTs in Jordan. Neck, shoulder, and lower back were the most commonly affected body parts. Pain complaints were significantly higher in female, younger technicians, and as workload increased. Future studies are indicated to investigate the actual mechanisms causing WMSDs among DTs. Conflict of interest The authors declare no conflict of interest. References [1] [2]
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6. Limitation of the study [7]
Due to self-reported nature of the data collection in the study, dental technician could have over or under reported their pain. However, completing the questionnaire posed no direct benefit to the respondent so there was no incentive other than accurate responses. The study can be enhanced by objectively assessing the participants. The sample was limited to northern and middle region in Jordan which may limit the generalizability of the findings; however the practice type is not supposed to be different. The nature of
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Work 56 (2017) 617–623 DOI:10.3233/WOR-172524 IOS Press
Work-related musculoskeletal disorders among Jordanian dental technicians: Prevalence and associated factors Zeid Al-Hourania,∗ , Mohammad Nazzalb , Yousef Khaderc , Khader Almhdawib and Abdel Rahim Bibarsa a Department
of Applied Dental Science, Faculty of Applied Medical Sciences, Jordan University of Science and Technology, Irbid, Jordan b Department of Rehabilitation Sciences, Faculty of Applied Medical Sciences, Jordan University of Science and Technology, Irbid, Jordan c Department of Public Health, Community Medicine, and Family Medicine, Faculty of Medicine, Jordan University of Science and Technology, Irbid, Jordan Received 17 August 2015 Accepted 20 October 2016
Abstract. BACKGROUND: Dental technology is a profession that requires precise manual skills and dexterous handling of small tools. There is an abundance research on work-related musculoskeletal disorders (WMSDs) affecting dentists, dental hygienists and dental assistants, yet very few articles investigated WMSDs among dental technicians. OBJECTIVES: This study aimed to determine the prevalence of WMSDs among Jordanian dental technicians and their associated factors. METHODS: A cross-sectional design was conducted. A sample of Jordanian dental technicians (n = 81) were asked to complete a validated structured self-administrated questionnaire to measure WMSDs and its associated factors. RESULTS: A sample of 81 dental technicians completed the survey (50.6% younger than 30 years, 61.7 were males). Pain complains were significantly higher in female, younger technicians, and with increased workload. All participants reported WMSDs in at least one body part in the last 12 months. The most common pain areas reported were in the neck (70.4%) and shoulders (71.6%). CONCLUSION: This study found a high prevalence of musculoskeletal complaints in dental technicians. Future studies are indicated to investigate the actual mechanisms causing WMSDs among dental technicians. Keywords: Dental technology, dental technician, occupational health, work-related musculoskeletal disorders
1. Introduction
∗ Address for correspondence: Dr. Zeid Al-Hourani, Department of Applied Dental Sciences, Faculty of Applied Medical Sciences, Jordan University of Science and Technology, PO Box 3030, Irbid 22110, Jordan. Tel.: +962 2720 1000 26885; Fax: +962 7201087; E-mail: [email protected].
Work-related musculoskeletal disorders (WMSDs) are common disorders affecting professionals working in dentistry related professions [1]. Common symptoms of WMSDs including fatigue, discomfort, limited ability of movement, and pain in joints, muscles, and tendons [2]. WMSDs are mostly
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associated with work patterns or using vibrating tools that include fixed or constrained body positions; such as repetitive movements, less resting period during breaks and concentrated force/movement on specific parts of the body, such as the back, neck, hand, or wrist [3–6]. Therefore, WRMDs might vary between professionals due to variability of the physical requirement of each profession. WMSDs are relatively common among dental professionals. Pain complaints are associated with abnormal or sustained prolonged posture during sitting or standing, strenuous position of the upper limbs, excessive tightening of hands and the use of vibrating tools [7]. There is extensive literature on the prevalence of WRMDs and its contributing factors to dentists, [7–11] dental hygienists [12] and dental assistants [13]; yet very few articles investigated WMSDs among Dental Technicians (DTs) [5, 14]. The nature of DTs’ work is different than of other dental professions. DTs also are exposed to mechanical vibrating forces produced by dental equipment such as the rotary hand-piece, wax knife, carvers and mixing bowls. Moreover their work requires the artistic aptitude for details and precision to fabricate various dental prostheses [15]. The Extensive use of tools is a well-known contributor to many upper extremity disorders [16]; peripheral nerve entrapment (e.g. median and ulnar nerve) is a common disorder acquired by the excessive vibrations of these tools [13]. DTs work requires high repetition and precision of hand movements, back and neck sustained flexion, and fixed upper extremity positioning [14]. Furthermore, a study conducted in Malaysia showed that the prevalence of back pain among all dental personnel was 44.4%; among those with the highest prevalence were DTs (52.4%) mainly due to poor posture [17]. This study was specific to low back and included heterogeneous sample of dental professionals without highlighting the associated factors to WMSDs among DTs. To the best of our knowledge, there is no study that specifically investigated the prevalence of WMSDs and its associated factors and impact on work performance among DTs. Therefore, the main aim of the study was to estimate the prevalence of WMSDs among DTs. Secondly, to identify personal and workrelated factors that are associated with occurrence of WMSDs for each body region. Finally, it aimed to study the work limitation due to WMSDs. In summary, estimating the prevalence and outlying the jobrelated factors of WMSDs among DTs would contribute to establishing awareness among practitioners,
developing precautions and preventive strategies as well as maximizing job satisfaction and efficiency.
2. Methods 2.1. Study design and study population A cross-sectional design was used. Cross-sectional design is the design of choice for surveying a prevalence of a certain topic in a population at one time [18]. Data was collected between November 2013 and March 2014. DTs with at least one year of employment in dental laboratories in all health sectors in the Middle and the Northern part of Jordan were included. Technicians with systemic disorders, history of musculoskeletal trauma, and pregnant women were excluded. In Jordan, there is estimated 300registered DTs. Among those technicians, around one hundred technicians who met the criteria were approached. The response rate was 81%. 2.2. Data collection procedure Data collection was conducted by trained research assistant (occupational therapist) who approached the eligible DTs in their offices. This study has been conducted in full accordance with the World Medical Association Declaration of Helsinki [19] and approved by the Jordan University of Science and Technology ethical committee board and the institutional review board. Technicians consented verbally to participate after full explanation of the study. The technicians were asked to complete a validated structured self-administrated questionnaire. The research assistant was available for any inquiry. 2.3. Instrument The questionnaire had two major sections. The first section was to collect relevant socio-demographic and work-related data. Socio-economic data collected were age, gender, and level of education. Work-related data collected were years of experience, number of working days per week, number of working hours per day, and work sector (governmental versus private). In addition, the questionnaire included some other questions related to rest breaks, length of rest break, job description (administrative versus technician), as well as, daily physical activities. This section was developed through intensive literature review and series of discussion among the
Z. Al-Hourani et al. / Work-related musculoskeletal disorders among Jordanian
research team members and expert DTs to ensure the validity of its content. This section consisted mainly of yes/no response format as well as a 5-point Likert scale format [20]. This first section was validated on a group of 8 DTs to ensure its comprehensibility. No changes were done on the questionnaire because all items were clearly understood by participants (those were not included in the analysis). The second section included an Arabic version of the Nordic musculoskeletal questionnaire [21] which was cross-culturally translated and adapted into Arabic for the purpose of using it in this study by MN (unpublished). The Nordic questionnaire is used to detect acute and chronic musculoskeletal complaints in the neck, shoulders and upper extremities, upper and lower back, thighs and lower extremities [22]. Its validation included both forward and backward translation. An expert committee then confirmed the final version. It was then conducted twice on a number of 40 individuals, 24 hours apart. The new adapted Nordic questionnaire was reported to have very good test-retest reliability as evidenced by kappa coefficient values ranging from 0.88 to 1.
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Table 1 The socio-demographic and job related characteristics of participants Variable Gender Males Females Age 15 years Working days 4-5 day 6-7 days Working hours ≤7 hours >7 hours Work sector Governmental Private
n
%
50 31
61.7 38.3
41 40
50.6 49.4
35 46
43.2 56.8
64 17
79.0 21.0
38 43
46.9 53.1
25 56
30.9 69.1
41 40
50.6 49.4
The socio-demographic and job related characteristics of participants are shown in Table 1.
2.4. Statistical analysis 3.2. Prevalence rates of musculoskeletal pain Data were analyzed using the Statistical Package for Social Sciences software, SPSS (SPSS Inc., Chicago, IL, USA) version 16 (16 SPSS Inc. 2007. SPSS for Windows, Version 16.0. Chicago, SPSS Inc). Percentages were used to describe categorical variables. The differences in prevalence rates were tested using chi-square test. Multivariate logistic regression analyses were performed to determine the factors associated with musculoskeletal disorders in each body part. A p-value of less than 0.05 was considered statistically significant.
3. Results 3.1. Participants’ characteristics This study included a total 81 DTs (50 males and 31 females). Almost half of them (50.6%) were younger than 30 years old. Less than half of the participants (43.2%) had a diploma education and 56.8% had a bachelor or higher degree education. Furthermore, almost 79.0% of the participants had experience less than 15 years, and more than half of the participants (53.1%) work 6-7 days a week; In addition 69.1% of the participants work for more than 7 hours per day.
Table 2 shows the prevalence of musculoskeletal disorders among DTs in each part of the body. All participants had at least one musculoskeletal disorder in a body part during the last 12 months. The most common musculoskeletal pain was found to be in the neck (70.4%) and shoulders (71.6%). About two thirds of the participants reported upper (65.0%) and/or lower back (66.3%) pain during the last 12 months. Work limitation due to musculoskeletal pain was reported by 46.6% to 63.2% of the participants. However, work limitations due to WMDs were more common in the elbow (56.3%), the lower back (62.3%) and the hip (63.2%). Moreover, musculoskeletal pain during the last 7 days was mostly common in the neck (50.5%), shoulders (53.8%), upper back (59.0%) and low back (56.0) body parts. The prevalence of musculoskeletal pain during the last 12 months according to socio-demographical and job-related characteristics is shown in Table 3. Musculoskeletal pain in the neck, shoulder and wrist were associated with at least one participant characteristic. Neck pain was reported in those who are younger than 30 years in comparison to the elder (80.5% Vs 60.0%). Shoulder pain was reported more by females compared to males (90.3% Vs 60%) whereas wrist
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Z. Al-Hourani et al. / Work-related musculoskeletal disorders among Jordanian Table 2 Prevalence rates musculoskeletal disorders in different body parts in dental technicians Body part
Neck Shoulder Elbow Wrist Upper back Lower back Hip Knee Ankle
Musculoskeletal pain in the last 12 months n % 57 58 16 38 52 53 19 31 26
Work limitation due to musculoskeletal pain n %
70.4 71.6 20.3 48.1 65.0 66.3 24.1 38.3 32.9
27 27 9 19 26 33 12 16 13
Musculoskeletal pain in the last 7 days n %
47.4 46.6 56.3 50.0 50.0 62.3 63.2 51.6 50.0
40 42 10 30 46 44 12 25 24
50.0 53.8 12.7 38.5 59.0 56.4 15.2 32.1 30.4
Table 3 The prevalence rates of musculoskeletal pain in the last 12 months according to socio-demographical and job-related characteristics Neck n (%) Gender Male 32 (64.0) Female 25 (80.6) Age 15 years 5 (29.4) Working Days/week 4-5 days 29 (76.3) 6-7 days 28 (65.1) Working Hours/Day ≤7 days 17 (68.0) >7 days 40 (71.4)
Shoulder n (%)
Elbow n (%)
Wrist n (%)
Upper Back n (%)
Lower Back n (%)
Hip n (%)
Knee n (%)
Ankle n (%)
30 (60.0)∗ 28 (90.3)
10 (20.0) 6 (20.7)
17 (34.0)∗ 21 (72.4)
31 (63.3) 21 (67.7)
34 (68.0) 19 (63.3)
13 (26.0) 6 (20.7)
19 (38.0) 12 (38.7)
16 (32.0) 10 (34.5)
33 (80.5) 25 (62.5)
10 (24.4) 6 (15.8)
25 (61.0)∗ 13 (34.2)
27 (67.5) 25 (62.5)
26 (65.0) 27 (67.5)
10 (24.4) 9 (23.7)
14 (34.1) 17 (42.5)
14 (34.1) 12 (31.6)
23 (65.7) 35 (76.1)
3 (9.1) 13 (28.3)
8 (24.2)∗ 30 (65.2)
24 (68.6) 28 (62.2)
27 (77.1) 26 (57.8)
10 (30.3) 9 (19.6)
16 (45.7) 15 (32.6)
13 (39.4) 13 (28.3)
46 (71.9) 12 (70.6)
14 (22.6) 2 (11.8)
35 (56.5)∗ 3 (17.6)
42 (66.7) 10 (58.8)
39 (61.9) 14 (82.4)
15 (24.2) 4 (23.5)
22 (34.4) 9 (52.9)
22 (35.5) 4 (23.5)
30 (78.9) 28 (65.1)
10 (26.3) 6 (14.6)
26 (68.4)∗ 12 (29.3)
24 (64.9) 28 (65.1)
22 (59.5) 31 (72.1)
9 (23.7) 10 (24.4)
14 (36.8) 17 (39.5)
15 (39.5) 11 (26.8)
21 (84.0) 37 (66.1)
5 (21.7) 11 (19.6)
9 (39.1) 29 (51.8)
14 (56.0) 38 (69.1)
13 (52.0) 40 (72.7)
7 (30.4) 12 (21.4)
8 (32.0) 23 (41.1)
8 (34.8) 18 (32.1)
∗ p-vale < 0.05.
pain was significantly more common in women, subjects less than 30 years old, those with a bachelor degree or higher, subjects with ≤15 years of experience and among those who reported working of 4-5days/week. 3.3. Multivariate analysis of factors associated with musculoskeletal pain The multivariate analysis of factors associated with musculoskeletal disorders (Table 4) showed that the factors that were significantly associated with musculoskeletal disorders in at least one body part were age, gender, education, and daily working hours. Elder participants were less likely to report neck pain (OR = 0.4). Females were almost 6 times (OR = 6.2) more likely to report shoulder pain than males.
Bachelor or higher education was associated with increased odds of elbow pain. Females (OR = 7.7), bachelor or higher education (OR = 8.3), working hours >7 hours/day (OR = 7.7) were significantly associated with increased risk of developing wrist pain. None of the studied characteristics was associated with musculoskeletal pain in any other body parts.
4. Discussion Studies that examined the WMSDs among DTs in terms of prevalence and its associated factors are scarce [2]. This is the first study to provide the prevalence of WMSDs among DTs and their associated factors. Consistent with the existing literature
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Table 4 Multivariate analysis of factors associated with musculoskeletal pain for each of body part as response variable Neck pain Age (≥30 vs. 7 hours vs. ≤7 hours)
[5, 7, 23], this study showed that the profession of dental technicians is associated with a high rate of WMSDs. This study highlighted the WMSDs among DTs using Nordic Musculoskeletal questionnaire, the most prevalent WMSDs were in neck, shoulder, upper back and lower back. The most relevant contributed factors to WMSDs among DTs were, age, gender, education, and daily working hours. Despite all of our participants being healthy individuals, every single one complained of work-related pain in at least one body part during the last 12 months. In this study the most common pain sites were in the neck (70.4%), shoulders (71.6%) and lower back (66.3%). This is consistent with previous studies on health workers and dental professions WMSDs [24, 25]. In dental professions, neck and lower back pain are highly associated with working postures that may exert high pressure on intervertebral disk as well as prolonged spinal hypomobility [26]. Furthermore, increased biomechanical stress is consideed as a risk factor that might lead to spine and/or nerve roots degenerative changes and subsequent related pain [13, 27]. Nevertheless, back pain has been found to be a major occupational health hazard also in other dental professions [13]. Neck pain was most common in DTs younger than 30 years old. Around 79% of the participants have had a work experience of less than 15 years which might indicate inefficient work skills or habits/patterns due to lack of experience. In addition, some argue that older population have an increased pain tolerance or adapt better to pain compared to younger population [28, 29]. Consistant with the literature, younger dentists have a higher frequency of musculoskeletal pain and discomfort than older colleagues [30]. In this study, wrist and shoulder pain were significantly higher in female as compared to male. Carpal tunnel syndrome is more prevalent in dental
OR (95% confidence interval)
P-value
0.4 (0.1, 1.0)
0.047
6.2 (1.7, 23.3)
0.007
4.8 (1.2, 19.8)
0.028
7.1 (1.9, 26.8) 8.3 (2.3, 30.9) 7.7 (1.9, 31.2)
0.004 0.001 0.004
professionals, especially in women [27, 31, 32]. It is well documented that certain WMSDs are more common among female dental professionals. For example, a study demonstrated higher prevalence of neck pain among female dentists as compared to males [30]. Other studies reported that wrist and hand pain including CTS are most common among female dental professional [33, 34]. The differences among genders still remain unknown; yet some studies suggest that females might have higher sensitivity to pain and therefore usually report more pain complains than males [35, 36]. Moreover, other studies suggests that females usually show substantially higher muscular activity in relation to their capacity, making them more prone to exertion and eventually hurting their muscles and joints more [37]. Synthasizing these studies results might explain the increased levels of pain among female DTs when compared to male colleagues. The workload of the participants is considered a heavy and a demanding workload. Around 53% of participants work 6 or more days per week and around 69% of our participants work 7 or more hours per day. Being a DT in Jordan requires generally to work long hours considering that most of the DT laboratories are owned and operated by private bussinesses whose major concern is profit. Many of these bussinesses employ cost-effective strategies that demand employees to produce as maximum dental prosthesis as possible in less time as possible. This forces DTs to carryout repetitive tasks in repetitive or static postures [1]. It is well documented that repetitive stress could result in repetitive trauma which could explain the high WMSDs among our participants. The presented data showed that increased working load of participating DTs (working hours >7 hours/day) was significantly associated with wrist pain. This is consistent with the WMSDs research
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among other dental health professionals revealing high association between WMSDs affecting upper extremities and high workload [38, 39]. Generally, as job requirements increase, most musculoskeletal symptoms also increase [40]. Furthermore, longer exposures to awkward postures might lead to increased musculoskeletal complains [41]. Previous studies on DTs have not discussed high prevalence of wrist pain yet it might be common among DTs due to the repetitive precise nature of their work using rotary instruments and carrying out finishing and polishing procedures for various dental prosthesis fabricated in the dental laboratory [14]. 5. Clinical implications Specific studies on effective interventions to prevent or treat WMSDs among DTs lack in the literature. DTs are generally advised to adhere to recommendations obtained from other dental professions and general population studies. There are many suggested conservative interventions available for other dental professions to reduce the effects of WMSDs [42]. These interventions can be categorized into physiotherapy and exercises, ergonomics, behavioral modifications and other interventions [6]. Using proper ergonomic tools, taking enough breaks, reducing working load are few suggestions to reduce WMSDs among DTs [6, 43, 44]. This study reported that certain DT categories are more prone to WMSDs than others. Female and young DTs are advised to take more precautions to avoid potential WMSDs especially those of wrist and neck. In general, there should be a focus on prevention rather than remedy. Education workshops on proper ergonomics in the workplace can be pivotal in reversing this phenomenon among DTs especially among the more prone category; female and young DTs.
work in dental technology is not expected to be significantly different across countries since technician’s manual procedures fabricating dental prostheses are similar. 7. Conclusions This study concluded a high prevalence of musculoskeletal complaints among DTs in Jordan. Neck, shoulder, and lower back were the most commonly affected body parts. Pain complaints were significantly higher in female, younger technicians, and as workload increased. Future studies are indicated to investigate the actual mechanisms causing WMSDs among DTs. Conflict of interest The authors declare no conflict of interest. References [1] [2]
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Due to self-reported nature of the data collection in the study, dental technician could have over or under reported their pain. However, completing the questionnaire posed no direct benefit to the respondent so there was no incentive other than accurate responses. The study can be enhanced by objectively assessing the participants. The sample was limited to northern and middle region in Jordan which may limit the generalizability of the findings; however the practice type is not supposed to be different. The nature of
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