Work-related Musculoskeletal Disorders and Associated Factors among Dental Professionals in Tanzania

INTRODUCTION

Musculoskeletal disorders (MSDs) have been defined as health problems of the locomotor apparatus, i.e., muscles, tendons, the skeleton, cartilage, ligaments, and nerves.¹ They are becoming an increasing problem globally for dental professionals.² A systematic review of MSDs among dental professionals has shown that the global prevalence of work-related MSDs among dental professionals ranges from 64 to 93%.³ A study conducted in Greece has reported the prevalence of MSDs among dentists to be 62%.⁴ In the African region, a study done in Cameroon documented the prevalence of work-related MSDs among oral health workers to be 78.7%.⁵

Dentists and other dental professionals are at risk of developing musculoskeletal due to the nature of their work. They are required to be at a certain position, performing certain repetitive movements and using vibrating instruments for a specific period of time every day of their working lives. The World Dental Federation in 2007 has identified risk factors for dentists and categorized them into work-associated (physical and psychological) and nonwork-related. The physical work-associated factors include deviated postures, long working hours, and nonergonomic working place/tools, whereas the psychological work-associated factors are time, pressure, and financial matters. The individual and nonwork-related factors can be smoking, obesity, lack of physical exercise, etc.⁶ It has been shown that working with an assistant resulted in fewer problems and there is an association between body mass index (BMI) and MSDs.⁷ A study done in KwaZulu-Natal, South Africa, found that 99.1% of the dentists experienced musculoskeletal pain in one or more sites. There was a strong association between the number of years in practice and work-related pain in the neck.⁸

MSDs can present as pain, swelling, tenderness, numbness, and loss of strength at the neck/shoulder region, lower back, wrist/forearm, upper back, etc. According to the report by the World Health Organization, MSD-related conditions are the second largest contributor to disability worldwide, with low back pain being the single leading cause of disability globally.¹ These conditions limit efficiency, movement, and dexterity of a person significantly and can result in absenteeism from work or even early retirement from work. Upper body symptoms have been noted to be higher than lower body symptoms.^3,9 Symptoms in the shoulders (75%), neck (72%), and lower back (66%) compared to the lower body (hips, buttocks, legs, knees, ankles, and feet) which ranged from 13 to 15% have been reported among dentists in Taiwan.⁹

Despite these disorders presenting as important hazards for the professionals that can negatively affect their performance and efficiency, very little is known about the epidemiology of MSDs in Tanzania. This study was therefore carried out with an objective of determining the prevalence of MSDs and associated factors among dental professionals in Tanzania.

MATERIALS AND METHODS

This was a cross-sectional descriptive study that was conducted between October 2018 and January 2019 in public and private clinics in Tanzania. The sample population included all practicing dental professionals, i.e., dentists, dental therapists, assistant dental officers, and dental laboratory technicians who work in the identified clinics.

The sample size was estimated using the formula

where

• N is the amount of desired sample.
• Z is the standard normal deviation, a constant at 95% confidence level which is 1.96.
• P is the proportion of the population affected by MSDs. This is estimated to be (78.7%) 0.787, from the study done in Cameroon.⁵
• D is the marginal error or the degree of uncertainty, desired at 5%.

Therefore,

A self-administered questionnaire inquiring about sociode-mographic characteristics, factors related to chronic medical conditions, and participation in other recreational activities was used to collect data. Questions pertaining to the practice of dentistry included duration of employment, working posture, patient workload, working hours, use of dental instruments, type of treatment frequently provided (endodontics, extractions, etc.), use of dental chair, and tendency to take breaks between patients. The questionnaires (257) were sent out to randomly selected clinics from a list of clinics obtained prior; however, only 164 questionnaires returned, out of which 9 were poorly filled, hence were excluded, and a total of 155 questionnaires were used for analysis.

Musculoskeletal complaints were explored using the standardized Nordic questionnaire by Kuorinka et al.,¹⁰ which assesses the presence of any musculoskeletal complaint and identifies regions suffering from musculoskeletal symptoms (MSS). Regions included are neck, shoulders, elbow, wrists/hands, upper back, lower back, hips, knees, and ankles/feet. This tool was validated in a pilot study among dental professionals in Dar es Salaam and a good response was achieved. Dental professionals who were not willing to participate in the study, who were not practicing, and or are retired were excluded.

The collected data were coded into the computer. Analysis was done using computer Statistical Package for the Social Sciences (SPSS) software version 20.0. The age was dichotomized into ≤45 years and >45 years; years of practice was dichotomized into ≤5 years and >5 years, and the BMI was grouped into underweight (<18 kg/m²), normal (18–24 kg/m²), and overweight and obese (>24 kg/m²). For data presentation, mean for continuous variables and percentages for categorical variables were used. Chi-square test was used to determine the associations between two variables, and p-value was set at p <0.05.

The study was approved by the Institutional Review Board of the Muhimbili University of Health and Allied Sciences (MUHAS). Informed consent was obtained from participants after the nature and purpose of the study were explained. Participation of the professionals was entirely voluntary and they had the right to withdraw from the study any time they wished. For confidentiality reasons, all respondents were registered in the study using serial numbers rather than names.

RESULTS

A total of 155 dental professionals responded to the questionnaire. Majority (75.5%) of the respondents were male with a male-to-female ratio of 3.1:1. The age range of the participants was from 24 to 70 years, with a mean of 37.94 ± 8.96 years. Most (63.9%) participants were dentists, with work experience of over 10 years (Table 1) and had no chronic medical condition (hypertension, diabetes, etc.).

Only a few (10%) participants suffered from underlying chronic medical conditions such as hypertension, diabetes, bronchitis, and cervical spondylosis. More than half (57%) of the participants were either overweight or obese (Fig. 1).

Majority (79%) of the dental professionals reported experiencing symptoms of MSDs. The lower back was the most (54.2%) affected body part followed by the neck and upper back, while the hips and legs were the least affected (Table 2).

Among the factors assessed for the association with MSDs, only BMI, years of practice, and type of mostly performed treatment were found to have a statistically significant association (p <0.05) (Table 3).

DISCUSSION

The study captured all cadres of dental professionals who were actively participating in clinical work in Tanzania, of whom the majority (63.9%) were dentists. This illustrates the real situation in clinical practice. The majority (75.5%) of the respondents in this study were male which is in contrast to the results from a study done in Southern Thailand where the majority of the dental health workers were female.¹¹ The reason for a higher number of male dental professionals may be attributed to the likelihood of male students taking science subjects (which are a requirement for admission into medical/dental school) in their high school education as compared to their female counterparts.

In this study, most (67%) of the dental professionals were aged below 45 years, and this reflects the general age profile of dental professionals in the country. The reason for this rather young profile could be the duration of the course and a recent commencement of the dental studies in the country (i.e., earlier 80s).

In the current study, slightly more than half (63.2%) of the respondents had BMI above the normal range. This finding may be attributed to the fact that dentistry is a time-consuming profession that involves long hours of static postures and a heavy workload that leaves no time for recreational activities and physical exercise. Furthermore, it is a relatively good earning profession that can favor adoption of a sedentary lifestyle.

The prevalence of symptoms of MSDs in this study is concurrent with the results of a study conducted in Cameroon which found the prevalence of MSDs among oral health workers to be 78.7%.⁵ A study conducted in Barcelona, Spain, in 2011 found that 79.8% of the dentists had musculoskeletal pain.¹² This high prevalence of MSDs affects more than half (79%) of the dental professionals in Tanzania, who could be prone to having a shorter time of efficient work and stay in the profession.

The factors associated with the development of MSDs among the studied dental professionals included BMI, number of years in practice, and type of treatment mostly performed. Majority (84.7%) of those who were either overweight or obese had experienced MSS. This may be explained by the reduced flexibility and excess load on weight-bearing areas such as the lower back. A study conducted in New Zealand found an association between BMI and MSDs.⁷ This further reveals that the BMI of a dental professional can play an important role in their risk of developing MSDs.

In this study, participants who had practiced for more than 5 years experienced more MSS than those who had practiced for less than 5 years. It may be hypothesized that the participants who have been practicing for less than 5 years have had recent training/graduation, thus observing good ergonomics in practice and availability of appropriate dental equipment and instruments that were nonexistent in the past.

Dentistry is a demanding profession considering that it entails adopting different positions while treating patients, requirement of repetitive movements, and the use of high-frequency vibration tools.⁴ The cumulative effect of these practices predisposes one to develop MSDs over time. A study conducted in KwaZulu-Natal, South Africa, found a strong association between the number of years in practice and work-related pain.⁸

The findings of the study depicted that MSS were more common among the dental professionals who often performed orthodontic treatment and restorative treatment as compared to those who routinely performed oral surgical procedures. This may be explained by the fact that most of the orthodontic and restorative treatments require the dental professional to be seated and in a stationary posture for most of the time which puts more strain on weight-bearing areas such as the lower back.

Although female dental professionals were found to experience more MSS than their male counterparts, this experience was not statistically significant. A study done in 2001 in Sweden reported that MSS was more among female dental professionals.¹³ In our study, age of the dental practitioners was not associated with MSS, findings which were in concurrence with a study done in India.¹⁴ Likewise, the functionality and adjustability of the dental chair were associated with MSS. This could probably be because unlike in the past, majority of the dental professionals these days use a fully functional and adjustable dental chair. These findings suggest that MSS may be attributed to other factors other than the functionality of the dental chair.

With regard to the most affected body parts by MSDs, it is apparent that the upper body symptoms are more prevalent than those on the lower body symptoms, especially the lower back. This can be attributed to the fact that dentistry requires more upper body involvement than lower body involvement. This finding was in agreement with the study conducted in Taiwan.⁹ On the contrary, a study conducted in southeast Turkey among dentists reported that the most common symptoms were foot-leg pain.¹⁵

The findings of the current study shed light on the severity of MSDs among dental professionals. In addition, it emphasizes the need for an intervention that can include physical ergonomics and cognitive ergonomic interventions.

The main limitation of this study was that the sample size was not reached, yet the findings of the current study shed light on the severity of MSDs among dental professionals in Tanzania. In addition, it emphasizes the need for an intervention that can include physical ergonomics, cognitive ergonomic interventions, and organizational ergonomic interventions.

CONCLUSION

The symptoms of MSDs are very common among dental professionals in Tanzania. Duration of practice, BMI, and type of treatment mostly performed were significantly associated with the development of MSS. The lower back was the most affected body part.

RECOMMENDATIONS

• Dental professionals should strive to observe ergonomics during practice, take breaks in between patients so as to reduce stress on weight-bearing areas, e.g., lower back.
• Dental professionals should be cautious of their weight by observing their diets and engaging in physical exercises.

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