Work related muskuloskeletal disorders among dentists at the university dental clinic in Skopje

Summary Introduction Musculoskeletal disorders (MSDs) are one of the most common types of work-related diseases that affect health workers, especially dentists. The aim of our study was to examine the presence of musculoskeletal disorders among dentists at the university dental clinic in correlation with risk factors. Materials and methods A questionnaire survey was carried out among 78 dental practitioners aged between 20 to 60 years old, employed at the university dental clinic. Questions included data on physical and psychosocial workload, perceived general health and occurrence of musculoskeletal complaints in the past 12 months, chronic complaints, frequency and length of breaks, exercising habits as well as medical care seeking. Results Pain in the back, neck and shoulders (84.6% / 85.9%) was the most common complaint among the majority of respondents, while reduced range of movement was noticed among significantly fewer subjects, mostly between 40-60 years of age. Prolonged statistic position was considered to be one of the main causes of MSDs (82.05%) while 73.08% of respondents stated at least two more reasons beside this one. Conclusion The percentage of MSDs prevalence among dentists in public health sector is high. More extensive surveys should be undertaken to cover larger group of dentists from both private and public sector, in order to obtain complete analysis of the prevalence of occupational disorders in our country.


INTRODUCTION
According to the US department of Safety and Health Administration musculoskeletal disorders (MSDs) develop as a result of imbalance between the level of demand of physical effort at the workplace and physical capacity of worker [1]. Despite having physical and psychological effects, professional disorders can impact worker's economic state and wellbeing on a larger scale, which contributes to more frequent absence from work and early retirement [2]. Some of professional hazards in dentistry are exposure to chemical substances, radiation, dangerous biological materials and inadequate body positioning during work. Based on data received from the Occupational Information Network and US Department of Labour database, dentistry was ranked as profession that has the worst impact on the health of workers [3].
Musculoskeletal disorders are one of the most common types of work-related diseases that affect health workers, especially dentists. There are multiple factors that contribute to development of musculoskeletal disorders among dentists [4]: continuous movements, insufficient lighting, improper body position during work, psychological stress, genetics, physical conditions, age and weight [5,6].
Ergonomics is a science about design of products and regulations that assure maximal utility and safety during work. It also studies relationship between workers, equipment and work environment. The implementation of ergonomic conditions and principles in the work place is important element in the prevention of musculoskeletal disorders and improvement of productivity and effectiveness of dentist for a longer period of time [7].
The aim of our study was to examine the presence of musculoskeletal disorders among dentists at the university dental clinic in Skopje in correlation with work-related risk factors.

MATERIAL AND METHOD
This study examined 78 dental practitioners aged between 20 to 60 years old, employed at the public health institution Dental Clinic Centre. They were given a Standard Nordisk Questionnaire consisting of two parts [8]. The first part consisted of questions regarding the gender and age, years of working experience, average working hours per day and per week, number and length of their breaks and position of their bodies while working.
The second part (Standard Nordisk Questionnaire) consisted of questions addressing the musculoskeletal disorders, the presence of genetic predisposition, the frequency of painkiller usage and questions regarding diagnosis and request for medical help among patients with these disorders.
In addition to the Standard Nordisk questionnaire, another questionnaire was distributed. This questionnaire addressed frequency and length of breaks, position of body during work, exercising habits, wearing orthopedic shoes and utilization of alternative methods for improving health. The obtained results were analyzed with descriptive statistical analysis.

RESULTS
The research was conducted on 79.59% (79/98) of the total number of dental employees at the University dental clinic, Skopje. Employees that did not participate in the research were absent due to illness, lack of time or other subjective reasons. The sample consisted of specialists 87.18% (oral surgeons, prosthodontists, orthodontists, pedodontists, periodontologists and endodontologists) and 12.82% general dentists. Most of the participants held a postgraduate degree (MSc, PhD).
Gender distribution among the participants was not equal. 73.08% of respondents were female at age 20-60, with an average working experienceof 16.9 years. The average working experience of male participants was 17.24 years. Furthermore, the amount of effective working hours among 82.05% of the respondents was 30 hours per week, while 17.95%, out of which were mainly male respondents, worked effectively for 40 hours per week. Table 1 shows work related reasons that caused musculoskeletal disorders or discomfort. 57.69% of respondents showed genetic predisposition. 82.05% of respondents spent significant amount of time in the same position while working, 52.56% respondents reported that their work required investing lot of strength, 62.82% reported their work required repetition of movements. Furthermore, 66.67% of the respondents reported exposure to constant machine vibrations as a part of their every day work, while 73.08% described two or three work-related conditions at the same time.
Another part of our research focused on pain and other complaints related to the musculoskeletal system (Table  2), where 66 respondents (84.61%) reported pain in the lower back, out of which 33.33% reported back pain in the last 12 months. Upper back pain was noticed among 60.26% of respondents, of which 19.23% have been experiencing pain in the last 12 months. 14.10% of respondents had reduced movements, all of the age group of 40-60 years with an average length of working experience, 22.5 years. None of the respondents from the age group of 20-40 years reported presence of upper back pain. The majority of respondents (85.9%) of both age groups reported the presence of shoulder and neck pain. Moreover, 28 (35.9%) examinees reported pain in hand fingers, while 14% of examinees experienced reduced hand strength, while holding instruments. All subjects had multiple musculoskeletal conditions. 47.44% of respondents used painkillers often and 33.33% of respondents used painkillers on occasional basis. However, despite the high prevalence of complaints among respondents related to pain in different parts of the MS system, only 37.18% sought professional help and have been diagnosed with MSD.
The results further showed that 51.28% of respondents were familiar with ergonomic principles of work, while 43.59% were more informed. Partial application of ergonomic principles was noticed among 55.13% of respondents and only 14 respondents (17.95%) fully applied them during work. Another finding was that most of respondents (67.97%) worked in both positions, seating  Have been taking proper medications/ painkillers Uzimali lekove protiv bolova and standing and only 6.41% of the respondents (mostly from the group of 20-40 years) were working in seating position (Table 3).
Almost all respondents were familiar that exercise, massage, physical therapy and other alternative methods affect musculoskeletal system and reduce the occurrence of musculoskeletal disorders, but only 40 (51.28%) occasionally went to physical therapy and 41.03% occasionally got massages. Only 26 (33.33%) respondents exercised frequently while 48% exercised occasionally even though exercise (strength and muscle stretching) is one of the most important factors for the preservation of the musculoskeletal system health (Table 3).

DISCUSSION
The term MSDs refers to injuries that affect soft tissues such as muscles, tendons, ligaments, joints, cartilage and nervous system. These conditions most often affect arms and back and are known as cumulative disorders caused by trauma, repetitive movements, stress, or as a syndrome of occupational overload. MSDs develop gradually within weeks, months and years and in a longer period of time may cause disabilities [9].
Several studies have examined the relationship between the occurrence of MSDs and type of profession. Dentists belong to vulnerable group constantly exposed to the threat of occupational disorders due to their static activity while working continuously for a longer period of time. Other factors that contribute to the presence of MSDs are lack of small breaks, constant repetitive movements of the arms and wrists and use of force while working [10,11]. Another important factor that influences the occurrence of musculoskeletal disorders is working environment. According to Custodio, the positions recommended by ISO and FDI, for patient and dentist (for example, the patient is in laying position and at the "9 o'clock" orientation to the dentist) are rarely observed due to the limited workspace [12]. In their study, Burke, Main and Freeman have come to the conclusion that approximately one third of dentists are forced to retire early because of work-related difficulties [13]. A number of dental studies reported that on average, two out of three dentists experienced musculoskeletal pain [14,15]. Most commonly reported disorders of this kind occur around spinal area, shoulders and wrist that can result in lower back pain, neck pain, brachial pain, shoulder tendonitis, carpal tunnel syndrome etc. [16,17,18].
Sartorio et al. indicated higher presence of MSDs (54-93%) among dental staff in Italy and significantly higher risk of exposure among senior and female dentists [19]. This study further showed that backbone, shoulder, elbow and arm were most affected.
Our research was conducted in order to investigate the prevalence of musculoskeletal disorders among dentists in the largest public health institution in our country. Seventy-eight dentists aged 20 to 60 years participated in the study. Both female and male participants were involved, specializing in different dental areas and most of them held a postgraduate degree (Master's or Doctoral Degree).
The pain in the back, neck and shoulders was the most common complaint among the majority of respondents, while reduced range of movement was noticed among significantly fewer subjects, mostly between 40-60 years of age. An interesting finding was that all examinees experienced more than one musculoskeletal disorder. Furthermore, hand pain was present with significantly lower percentage compared to the pain in the back, neck and shoulders that was connected and dependent on the area of specialty. Our examination included respondents from different dental areas of specialty that share similar positioning of neck, shoulders and spine while working. The application of force at work and vibrations is related to only few dental areas that require use of hands and fingers and that explains low percentage of complaints related to hand and finger disorders.
The results of our research agree with the results presented by several authors. Legg and Smith surveyed 285 Australian dentists, out of which 90% practiced general dentistry, and most of complaints were related to neck, shoulder, and back. About 37.5% of dentists needed medical care, while 25% reached the point of disability and 9% required prolonged absence from their practice [20]. Alexopoulos EC et al. concluded that hand/wrist complaints (46% / 60%) were one of the most important occupation related musculoskeletal disorder and ergonomic and educational interventions could hold a prominent role in its prevention [21]. Several authors pointed out that position of dental chair needed to be adjusted according to the height of the dentist, together with the light source, in order to prevent the occurrence of MSDs [22]. Furthermore, the results show high percentage of lower back pain that can be related to working conditions as large number of respondents had long work experience or inability to apply ergonomic principles of work (defective workplace, poor lighting, inability to work in a seating position, etc.). Prolonged statistic position is considered to be one of the main causes of MSDs and should be addressed properly in order for dentists to practice preventive measures [23,24]. These findings correspond with data obtained from our survey where 82.05% of respondents reported prolonged static posture as a cause for disorders and 73.08% of respondents reported at least two more reasons beside this one.
Recently, several studies have highlighted other factors such as obesity and physical inactivity in the development of chronic MSDs among dentists. Moreover, due to exhaustion and fatigue, caused by heavy workload and long working hours, dentists avoid physical exercise and activities [25,26]. Published literature points out the important role of physical activity (pilates, aerobics) as a preventative ergonomic measure. Aerobic exercise improves the flow of oxygen in tissues, thereby increasing efficiency. Stretching exercises are effective measure for relaxing and reducing muscle tension caused by improper posture [27]. It is well known that prolonged static posture requires contraction of 50% of body's muscles explain the need for stretching.
Even though all respondents from our research were aware that regular exercise is of exceptional importance to the musculoskeletal health, only one third of respondents exercised regularly, while 48% exercised only occasionally. The percentage of respondents who were utilizing alternative methods such as massage or spa centers was even lower. Besides the high percentage of musculoskeletal complaints among respondents, only 37.18% sought professional help and only 47% took medication to reduce pain, which comes as a result either from the respondent's negligence or the frivolous approach to this issue.
This study covered only dentists employed in the public sector. Further studies are advised to examine dentists from private dental institutions, where working conditions impose more complex schedule of work, fewer breaks and free time as well as fewer absences from work.

CONCLUSION
The percentage of MSDs prevalence among dentists in public health sector is high. More extensive surveys should be undertaken to cover larger group of dentists from both private and public sector, in order to get complete analysis of the prevalence of occupational disorders in our country. Consequently, appropriate measures should be taken in order to inform and educate dentists regarding MSD. Awareness should be raised pointing out that dentistry, as a profession, is susceptible to high risk of occupational disorders and injuries. Ignorance and avoidance of the MSDs symptoms could lead to early career ending and therefore it is important to have a knowledge regarding its prevention.