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Journal of Back and Musculoskeletal Rehabilitation 28 (2015) 755–759 DOI 10.3233/BMR-140579 IOS Press

Musculoskeletal disorders among a group of Iranian general dental practitioners Aram Tirgara , Khodabakhsh Javanshira, Arash Talebianb, Fatemeh Aminic and Alireza Parhizc,∗ a

Motion Disorder Research Center, Babol University of Medical Sciences, Babol, Iran Dental College, Babol University of Medical Sciences, Babol, Iran c Dental College, Tehran University of Medical Sciences, Tehran, Iran b

Abstract. BACKGROUND: Dentists have to remain in a fixed position during dental practices for the accuracy required, therefore they are susceptible to musculoskeletal disorders (MSDs). OBJECTIVES: Considering the infrequency of ergonomics studies in general dental practitioners (GDPs), especially in cervical region, this study aimed to reviews MSDs in the neck region among GDPs. METHODS: An analytic cross-sectional study was carried out among the GDPs in 2011. A total of 60 dentists (40 males and 20 females) were examined through a combination of questionnaires (concerning their demographic information) such as the Nordic standardized musculoskeletal disorder questionnaire (NMQ) and Body Discomfort Assessment questionnaire (BDA). Each dentist’s working posture was assessed using Rapid Upper Limb Assessment (RULA) and deep cervical flexor muscle endurance through a Craniocervical Flexion test (CCFT). Descriptive statistical indexes and Chi-square test were used for statistical analysis, while considering p < 0.05. RESULTS: The mean dental practice experience was 16.9 ± 5.6 years with average 41.2 ± 13.4 working hours per week. About 45% of dentists took regular exercises weekly. Some 83.3% of these dentists expressed to be suffering from the cervical pain, whereas, 56.7% complained about back pains and 41% shoulder problems. Female dentists were found more at risk of neckache, discomfort and pain in shoulder and hand than males. Greater pain frequency in knee was found in more experienced and older age dentists (P = 0.07). Results from the CCF test showed that the deep cervical flexor muscles endurance increased with regular exercise and decreased with aging. CONCLUSION: Many dentists experience the MSDs, especially in cervical region, as a consequence of occupational stresses. Therefore, detecting occupational risk factors, standards of work position, regular exercise and following ergonomic policy are intensely recommended. Keywords: Musculoskeletal disorders (MSDs), Rapid Upper Limb Assessment (RULA), ergonomics, Craniocervical Flexion Test (CCFT), dentistry, general dental practitioners (GDPs)

1. Introduction Work-related Musculoskeletal Disorders (WMSDs) are one of the most common occupational hazards [1]. About 11.6 million days were expired in 2005 due to MSDs based on American Statistical Association ∗ Corresponding author: Alireza Parhiz, Oral and Maxillofacial Surgery Department, Shariati Hospital, Jalal Al-Ahmad Ave, Tehran, Iran. Tel./Fax: +98 21 22076110; Mobile: +98 912 5130627; E-mail: [email protected].

(ASA) research [1]. Unnatural and uninterrupted working postures, repeated and forceful hand movements and unsuitable equipments lead to MSDs which manifest mainly as pain [2,3]. According to the studies, 63– 93% of MSDs were reported in the neck, shoulders, back and hands [2,3]. Rundcrantz et al. (1991) reported that worldwide MSDs were common in cervical and upper regions more than the other areas of the body [4]. Dentists who used dental mirrors, avoided unnatural postures, had regular exercises and took a brief during dental practice were less susceptible to cervical and up-

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A. Tirgar et al. / Musculoskeletal disorders among a group of Iranian general dental practitioners

per regions MSDs [4]. This article investigates the frequency of MSDs, emphasizing the neck region among the dentists in Iran and additionally, expresses which parts of their bodies are most affected.

2. Methods An analytic cross-sectional study was carried out on 60 General Dental Practitioners (GDPs) (40 males and 20 female) in 2011. Each dentist had an experience of at least 5 years of general dental practice. The sample size was determined based on 80% frequency of MSDs [5,6] and 0.15% error. The dentists were randomly selected from private offices or clinics. The data were collected using RULA (Rapid Upper Limb Assessment), posture analysis technique, CCFT (Craniocervical Flexion test) and a three part questionnaire containing demographic aspects, Nordic standardized musculoskeletal disorder questionnaire (NMQ) and Body Discomfort Assessment (BDA) questionnaire. All the dentists were informed about the study both verbally and in written, signed and dated and an informed consent was obtained from them. The university’s Clinical Research Ethics Board approved the research protocol, including requirement procedures, questionnaires, analytic tests and the informed consent. Two observers examined all participants. 2.1. Demographic questionnaire Age, height, weight (in order to estimate the Body Mass Index), experience, weekly working hours and a note about regular exercise (at least 2 times a week) were requested in this part. 2.2. Nordic standardized musculoskeletal disorder questionnaire (NMQ) The Nordic questionnaire was developed in Scandinavian Institute of Occupational Health by Kuorinka et al. in 1987 [7]. NMQ can be used in different professions comparing low back, neck, shoulder pain and general complaints [7]. This study estimated the frequency of pain and work disturbance in dentists during the last 12 months and recent weeks. 2.3. Body discomfort assessment questionnaire (BDA) The intensity of pain and discomfort in the different parts of the body was estimated using this questionnaire which the amount of pain was changed from a

Table 1 Dentists demographic information Variable Mean Standard deviation Domain Age 43.85 6.640 35–65 Height 166.68 7.708 153–183 Weight 68.18 13.140 42–91 BMI 22.34 3.285 19.88–27.08 Experience (year) 16.88 5.551 10–35 Weekly working hour 41.20 13.43 30–49

qualitative variable to a quantitative variable. The intensity of pain was estimated based on a Visual Analogue Scale (VAS) representing zero as no pain and 5 as an intolerable pain [8]. 2.4. Rapid upper limb assessment (RULA) This ergonomic technique provides a quick assessment of the upper limbs and the risk of MSDs incidence [9]. This technique developed by McAtamney and Corlett needs no special equipment [9,10]. The tool determines the exposure of individual workers by scoring the work position, repetitive movements, forces and muscle activity using a coding system. The RULA action level verifies the degree of injury risk. The RULA score 1–2 represents no risk injury, 3–4 score some risks and requirements of investigations, 5– 6 score shows a poor position with a moderate risk of injury. Individual workers who get 7+ score have the worst working position and an immediate change is required [9]. 2.5. Craniocervical flexion test (CCFT) The CCFT is a valid clinical test estimating the action of deep cervical flexor muscles and their interaction with superficial flexors. This test is widely used in studies related to cervical pain and headaches [11,12]. The patient is in a supine lying position placing the neck in a natural posture. Before performing the test, a pressure sensor (pressure biofeedback unit-PBU) is placed behind the neck. Then, it is inflated to a stable baseline pressure of 20 mm Hg. The subject is asked to move his/her head as he/she nods slowly without lifting the head. This action increases the PBU’s pressure. The test consists of five progressive stages, during each stage pressure should increase 2 mm Hg and it reaches 30 mm Hg in the last stage. The patient is told to hold the pressure in each stage for 10 seconds and then relax back to the baseline position pressure for another 10 seconds. Each stage should be repeated ten times, otherwise, the number of repetition is recorded as the individual’s capability.

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Table 2 The frequency of pain, working discomforts and pain complaint due to BDA Organ Neck Shoulder Elbow Hand and wrist Upper back Midback (lumbar) knee

Frequency of pain within previous 7 days % Number 38.3 23 6.7 4 3.3 2 16.7 10 15 9 30 18 5 3

Frequency of pain within previous 12 months % Number 83.3 50 41 26 5 3 38.3 23 40 24 56.7 34 6.7 4

Frequency of pain interrupting work % Number 73.3 44 35 21 3.3 2 16.7 10 33.3 20 55 33 3.3 2

Pain complaint using BDA 1.72 0.53 0.05 0.33 0.57 1 0.07

Table 3 The RULA Risk levels and the required treatments RULA score 1–2 3–4 5–6 7+

Abundance − − 4 56

Relative abundance − − 6.67 93.33

3. Results

MSD risk level Negligible risk Low risk Medium risk High risk

Ergonomic recommendation No action required Change may be needed Change needed soon Implement change now

2.5 male

A total of 60 dentists (40 males and 20 females) participated in the study, whose characteristics are shown in Table 1. Through this investigation, the pain and working discomforts were found to be more common in the neck (83.3%–73.3%), waist (56.7%–55%) and shoulders (41%–35%) during the last 12 months (Table 2). Around 93% of the dentists experienced pain and a MSD in at least one region during the last 12 months. Forty six percent of them visited a therapist and 56.7% took pills. A distinct correlation was found between age, working experience, and the frequency of pain and discomfort in knee during the working year, using Chi-square test (P < 0.05). Neck, shoulder, wrist and hand pain were found more common in female dentists, than males who were suffering more from back pain (Fig. 1). On the basis of the RULA scores, 93.3% of the subjects had the worst position during restorative practices. Restorative tasks constitute the largest block of working hours among the different dental practices (Table 3). According to the RULA action level, an immediate change in the working posture is necessary for such dentists. On the basis of the CCF test, regular exercise increases the endurance of deep cervical flexor muscles, while aging decreases that. But less experienced dentists found to be more prone to MSDs. Using Chisquare test, no significant relation between flexion score and individual variability was found (Table 4).

female 2

1.5

1

0.5

0 neck

soulders

wrist and hand

midback

back

Fig. 1. Relation between distribution of pain intensity and sex.

4. Discussion Dentists are susceptible to MSDs since they have to remain in a fixed position during dental practice [1]. Although WMSDs are frequently seen among dentists, they are not well studied in Iran. The results of this study showed that 93.3% of dentists experienced at least one MSD during a working year, which generally occurred in the neck, shoulder, back, wrist and hand. Considering the mean age (43.9 years) and working experience (16.9 years) of the subjects, this finding needs a special attention. Based on 9 independent studies published in 2002, on average, each dentist will start to experience MSDs when he/she is about to finish the first half of all the years

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A. Tirgar et al. / Musculoskeletal disorders among a group of Iranian general dental practitioners Table 4 The results of CCF test on dentists of different character Variable Age Work experience Regular exercise

Category < 45 years > 45 years < 15 years > 15 years No Yes

Abundance 35 15 24 26 23 27

he/she works. Such work shows that with the frequency of 62%, MSD appear in the neck, 59% back and 40% wrist and hand [13]. In this study, pain was found more common in the neck region (83.3%). With respect to the gender, women constitute the larger population affected by MSDs; the ratio was 2/1.6 as the number of women affected divided by the number of men affected. Akesson et al. in 1997 reported 81% of cervical and upper limb discomforts among dentists, nurses and oral health workers, with a high prevalence of neck pain in females [14]. The results of this study correlate closely with mentioned study. In another study, cervical discomforts were reported at approximately 72% which was more common in younger dentists [15,16]. Our results are consistent with such findings. MSDs among the young and less experienced dentists have the high rates of 83.4% and 85.7%. The reason for such a high rate is the lack of enough professional experience and the incorrect postures at work (Table 4). For more experienced dentists, it seems that the cumulative effect of physical pressure and psychological anxiety is the main cause of cervical pain. As stated by Yip et al. in 2008, cranio-vertebral angle has an inverse relationship with age, forward head posture (FHP), cervical pain and discomforts. FHP can lead to neck pain but it is not the only cause [17]. Some 75% of dentists in our study hold a fixed neck position at 20 degrees or more. O’Leary et al. in 2007 studied the effect of CCFT and CF test on cervical flexor muscles [18]. A large number of studies indicate the dysfunction of cervical flexor muscles in patients suffering from cervical pain [19,20]. Our study confirmed that flexor muscle endurance increases by taking regular exercise (16.3% to 18.1%) and decreases with aging (27.8% to 24.2%) and less working experience (22.6% to 30.3%).

Flexion score 27.8 24.2 22.6 30.3 18.1 16.3

Domain 6.8–43.4 10.2–22.5 6.8–43.4 10.2–43.4 11.8–43.4 6.8–18.8

of the dentists in Iran are graded in high MSD risk level. In this regard, changing posture during dental practice, avoiding fixed and prolonged neck flexion, taking brief rest between consecutive patients, taking regular exercise and keeping standard working position are suggested.

Acknowledgments This study has been financially supported by Babol University of Medical Sciences (Code No. 9032035). The authors also thank Dr. Evangeline Foronda for proofreading the article.

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5. Conclusion Musculoskeletal disorders are widespread among dentists. On the basis of CCFT and RULA results, most

Standard deviation 21.5 16.7 13.2 24.3 11.7 8.6

[10]

Health and Safety Executive (HSE), Aging and Work related musculoskeletal disorders: a review of the recent literature, HSE, Derbyshire, 2010, 11. Ministry of labour, preventing musculoskeletal disorders (MSDs) at industrial workplaces, fact sheet # 26, January 2012, 1-2. SZYMANSKA J. Disorders of the musculoskeletal system among dentists from the aspect of ergonomics and prophylaxis. Ann Agric Environ Med. 2002; 9: 169-73. RUNDCRANTZ BL, JOHNSSON B, MORITZ U. Pain and discomfort in the musculoskeletal system among dentists. A prospective study. Swed Dent J. 1991; 15: 219-28. American Dental Association (ADA). Ergonomics for dental students: ADA INFOpak, Chicago, UAS, 2011; 1-4. RABIEI M. SHAKIBA M. DEHGJAN SHAHREZA H, TALEBZADEH M. Musculoskeletal Disorders in Dentists, International Journal of Occupational Hygiene. 2012: 4, 3690. KOURINKA I, JONSSON B, KILBOM A. Standardiesed Nordic questionnaires for the analysis of the musculoskeletal symptoms. Appl Ergon. 1987; 18: 233-237. ALEXOPOULOS EC, STATHI IC, CHARIZANI F. Prevalence of musculoskeletal disorders in dentists. BMC Musculoskelet Disord. 2004 Jun 9; 5:16. McATAMNEY L, NIGEL CORLETT E. RULA: a survey method for the investigation of work-related upper limb disorders. Appl Ergon. 1993 Apr; 24: 91-9. CHOOBINE A, TOSIAN R, ALHAMDI Z, DAVARZANIE M. Ergonomic intervention in carpet mending operation. Appl Ergon. 2004 Sep; 35: 493-6.

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Musculoskeletal disorders among a group of Iranian general dental practitioners.

Dentists have to remain in a fixed position during dental practices for the accuracy required, therefore they are susceptible to musculoskeletal disor...
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