Evaluation of knowledge and application towards ergonomic principles among undergraduate dental students

This study evaluated the knowledge and application of ergonomic principles as well as manifestation of pain by dental students at the Federal University of Maranhão. Forty-four students answered a questionnaire on ergonomic principles. Photographs of the clinical rounds were performed to evaluate the postures adopted, without the students knowing the moment of photographic registration, avoiding that they modified their posture. The relationship between theoretical knowledge and the applicability of ergonomics in dental setting was evaluated. Data were analyzed using descriptive statistics. The Chi-square test analyzed the distribution of categorical variables among the evaluation instruments (α = 5%). Most of the participants adopted a satisfactory posture and presented knowledge about ergonomic postures, however, one can observe the poor positioning of the eyes and spine. 75% of the patients experienced pain in the body, being the spine (61.4%) and neck (40.9%) the most affected sites. The sample evaluated had good knowledge on ergonomic principles, but these were not adopted entirety, which may have led to the onset of pain.


Introduction
Ergonomics is the science that brings a set of multidisciplinary knowledge applied in the workplace organization and the elements which make up labour activities, with the objective of assuring a safe, healthy and comfortable environment and preventing work-related diseases by improving the effectiveness of the service (Gopinadh et al., 2013).
Ergonomic conditions should provide a work situation which does not harm the health of those who do so, allowing them to be able to exercise their tasks and avoid work-related hazards (Oliveira et al., 2018).
In dentistry, ergonomics aims to reduce physical and mental stress, to prevent dental practice diseases related, to seek greater productivity, with better quality of life, comfort for the professional and, consequently, for the patient (Kee & Karwowski, 2007;Garcia, 2016;Sachdeva et al., 2020;Shobhana et al., 2020).
Although dentistry has evolved technologically in recent decades, there is a consensus on the lack of progress with regards to the professional's health (Ahearn et al., 2010). Nature of the dental profession and postures assumed by dentists during their work has an effect on their body (Sachdeva et al., 2020;Shobhana et al., 2020). The dentist acts repeatedly, performing clinically operational skills restricted to a small region as the oral cavity and requirements for precision in this region and the muscular exertion required in some dental procedures make these individuals very vulnerable to occupational risks (Garbin et al., 2011).
It is known that the prevalence of discomfort and musculoskeletal pain in dentists is higher than in the general population (Wilson et al., 2006;Michalak-turcotte, 2000;Shobhana et al., 2020), with neck, shoulders, upper limbs and, mainly, lower back the most sites being affected. These factors may result in the decline of the working production of the dental practitioners, with early withdrawal from work due to permanent or temporary disability (Hosseini et al., 2019;Saliba, et al., 2016;Evelyn & Jain, 2020). Most of the time, musculoskeletal disorders are sluggish to emerge; consequently, professionals end up getting used to pain or discomfort, and forgetting to take care of his/her own health (Saliba, et al., 2016).
In order to prevent work-related illnesses, as well as providing greater comfort and health to the professionals and patients, the International Standards Organization (ISO) and the Fédération Dentaire Internacionale (FDI) have promoted a Research, Society andDevelopment, v. 10, n. 14, e123101421561, 2021 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v10i14.21561 3 restructuring in order to standardize the daily work at the dental office, establishing ergonomic norms and guidelines, which should be adopted by dental professionals and academics (Garbin et al., 2011). The application of the principles of ergonomics to equipment and the workplace is an effective way to guarantee healthiness, safety, high performance, motivation and satisfaction in the dental set-up.
The acquisition of these knowledges must occur at any given moment of professional life, however, the earlier they are installed, greater will be the benefits, assimilation and incorporation, thus avoiding in the case of dental ergonomic posture, the formation of detrimental habits (Garcia et al., 2008;Kumar et al., 2012).
As dental students are also subject to occupational risks inherent to dental practice (Movahhed et al., 2013;Pejčić et al., 2020), researches on the knowledge and application of ergonomic principles by those individuals becomes relevant, aiming at prevention, awareness and early education, in order to take them to new postural conditions and better professional performance. Facing the exposed, the objective of this study is to assess the knowledge on ergonomic principles, as well as to identify the difficulties of clinical posture during dental practice and painful manifestation by final-year dental students at a public dental school in Brazil.

Study design:
This cross-sectional study was conducted at the dental clinics of the School of Dentistry of the Federal University of Maranhao from September to December 2017. Initially, the Research Ethics Committee of the University Hospital of the Federal University of Maranhao approved this study (nº 2,510,609).
The study population consisted of all last year undergraduated students of the School of Dentistry (in order to make the sample more homogeneous, as they have already studied Ergonomics and exercises similar clinical activities). A total of 44 students participated, whose Informed Consent was obtained.
Firstly, the students answered a questionnaire to evaluate their knowledge about ergonomic principles and painful manifestations. In addition, students were photographed during their clinical rounds to assess the application of ergonomic postures.

Data collection:
Participants answered a self-administered survey questionnaire with 14 objective questions regarding social data, painful manifestations and knowledge of ergonomic principles.
A pilot study was performed with students who did not make up the study sample, in order to assess the quality of the questionnaire. Questions that generated doubts were reformulated, until the questionnaire was fully validated.

Photographic record:
Photographs of the students during their routine dental procedures at the clinics were taken. Students were not informed when the photographs would be taken, thus preventing them from changing their posture, which allowed a reliable analysis of the positions adopted during the visits. Two previously calibrated evaluators analyzed the images independently.
For calibration, photographs of procedures performed by students who were not part of the study sample were taken and analyzed together by the evaluators, using the same assessment criteria that would be used in the study.
To analyze the photographs, a checklist-type evaluation system was used, according to the methodology adopted in other studies (Michalak-turcotte, 2000;Bendezú et al., 2006). The list contained nine items on ergonomic postures, related to the professional's positions and equipment used, following the specifications established by ISO (2006). Research, Society and Development, v. 10, n. 14, e123101421561, 2021 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v10i14.21561 4 For each item correctly performed by students, a 1 point value was assigned, as proposed by Garbin et al. (2011), with the following classification: 1 to 2 points -unsatisfactory; 3 to 4 points -regular; 5 to 7 points -satisfactory; and 8 to 9 pointsexcellent.

Statistical analysis:
Statistical analysis used GraphPad Prism version 9.1 (GraphPad Software Inc., San Diego, United States). Descriptive statistics was performed using measures of frequency, central tendency and dispersion. Pie and bar charts were used to represent the distribution of the sample data. The Chi-square test was used to assess the distribution of categorical variables among the types of assessment instruments: questionnaire or photographs. The level of significance adopted was 5% for all tests.

Results
The sample consisted of 44 students, the majority (61.4%) under the age of 25 and female (75%). Although more than half of the interviewees (68.2%) claimed to apply ergonomic principles during their clinical care, a substantial part (75%) experienced frequent pain and 70.5% reported experiencing pain during and / or after dental treatment (Table 1). Among the students who reported frequent pain and discomfort, 46% reported pain 1 time per month, 30% said they feel pain more than 1 time per week, 15% more than once a month, 6% once a week and 3% daily (Figure 1). Regarding pain distribution by anatomical location, the results showed back trouble to be the most prevalent (61.4%), followed by the neck (40.9%), the head (27.3%), legs (25%), arms (20.5%), eyes (11.4%) and other sites (11.4%) (Figure 2). In terms of the classification of ergonomic posture adopted by students during dental practice, through the evaluation of photographic records, it was observed that 38.6% of students adopted satisfactory working posture and only 6.8% inappropriately (Table 2).

Discussion
Ergonomics has been an ally in dentistry in terms of improving the work environment and reducing certain occupational musculoskeletal problems (Shobhana et al., 2020). Maintaining a proper posture would aid body in reducing its energy expense, improving the functioning of organs and it is protected against disturbances that can impair occupational practice (Garbin et al., 2011).
According to Oliveira et al. (2018), dental students are increasingly targets for developing disorders that affect both the muscular and the skeletal system, which can lead to extremely detrimental consequences in the future. This was evidenced in the present study, in which 75% of the participants reported experiencing frequent pain. Attention should be drawn to the fact that vast majority (95.5%) of participants were up to 30 years of age. As many individuals usually ignore the potential risk factors, this process can extend over time, resulting in temporary or permanent early absence from work due to disability.
At the Federal University of Maranhao, Ergonomics is taught in the 2nd year of the academic course, a period in which clinical training also begin. With the incorporation of Ergonomics into curriculum, it is expected that the individual, since the inception of the course be concerned with adopting correct postures during consultations, using equipment and instruments that enhance their work within ergonomic principles (Saliba, 2016;Evelyn & Jain, 2020).
It is known, however, that theoretical knowledge is not always sufficient in preventing work-related musculoskeletal disorders (Evelyn & Jain, 2020). The applicability of ergonomics in dental preactice is essential for good health, both physical and mental. Although faculty members can intervene and provide ergonomic feedback, improvements may not be sustained if students are unaware or unwilling to adopt the ergonomic principles in routine dental practice (Partido, 2017).
Previous studies conducted demonstrate lack of knowledge on the topic, as well as frequent inappropriate postures during dental practicing (Harutunian et al., 2011;Khan, 2013). According to a study carried out in India by Bathan (2016) involving dentists and students, only 33.3% had previous knowledge about ergonomics, while nearly 38.7% had participated in any workshop on prevention of musculoskeletal disorders. In another study conducted in Malaysia, about 58% of students reported that ergonomics had not been taught in their curriculum, while 93% of them had never participated in lectures on the prevention of musculoskeletal disorders in the dental school. The same percentage developed work-related musculoskeletal problems (Khan, 2013).
These data contrast with those found in the present study, in which 68.2% of the subjects reported applying ergonomic principles during their dental practice with patients, which was also confirmed by analysing the postures through photographs, in which 65.9% of students had adopted postures considered satisfactory or excellent.
On the other hand, although adequate postures were found in the vast majority of participants, 75% complained having frequently pain, among which 70.5% reported feeling during and/or after routine dental work. This survey, however, assessed only the position of students during dental procedures. It is known, however, that apart from work posture, other factors such as physical activity, levels of mental stress and work environment may contribute to the development of work-related musculoskeletal disorders (Mulimani, 2018), being important the development of future studies that assess these factors.
Furthermore, the clinical training for a fixed amount of time required by dental students is generally long, often lasting an entire shift, with no rests. According to a study by Khan (2013), only 20% of students reported exercising after clinical work, which is a key factor to prevent the onset of musculoskeletal disorders. The authors also concluded that students with long working hours at the clinic were 12 times more likely to report uneasiness in one or more regions of the body. According to Gupta et al. (2014), nearly 70 and 90% of dentists have recurrent episodes of pain, and one third of them continue to present recurrent or intermittent pain after the first episode. Hence, it is very important to identify ergonomic factors present in the dental workplace to prevent or reduce the risks of work musculoskeletal hazards.
Research has revealed that more than 70% of dental students have experienced neck, shoulders and lower back ache as early as the third year of dental practice (Rising et al., 2005). Literature review conducted by Mulimani (2018), the authors reported that the prevalence of back pain ranged from 22.2 to 91.0%, neck pain from 20 to 84.9% and shoulder pain from 18.9 to 73.5%. These data corroborate with those in the our study, in which 61.4% and 40.9% of the students reported feeling spine and neck pain, respectively.
The evaluations of this study revealed a scarcity of theoretical knowledge as well as poor positioning of the participants' spine and eyes, the latter positioned very close to the patient, leading to an excessive bending of the neck forward.
In addition, though most of the students adopted fairly correct neck position in both evaluations (questionnaire and photographs), it was noticed that a significant number (47.7%) of students tilted the neck sideways during clinical practice, which might justify the pains reported in these regions.

Conclusion
Overall, students evaluated had a sound knowledge towards ergonomic principles, as well as an adequate posture during routine dental procedures, but they did not put this into practice entirety, which may be related to the frequent discomfort reported by most of the interviewees.
It is therefore suggested that greater attention should be paid to dental graduates to implement the adoption of dental ergonomic principles throughout the course period, as well as the development of more studies on the subject. Such measures can significantly assist in reducing ergonomic-related heath disorders among these future professionals.