Medical

Communication

Biosci. Biotech. Res. Comm. 9(4): 814-820 (2016)

An interventional ergonomics program assessment of

dental students

Samane Gharekhani

, Aram Tirgar*

, Monireh Seyyed

and Hemmat Gholinia

Department of Pediatric Dentistry, School of Dentistry, Babol University of Medical Sciences, Babol, Iran

Department of Social Medicine, School of Medicine, Babol University of Medical Sciences, Babol, Iran

Department of Pediatric Dentistry, School of Dentistry, Babol University of Medical Sciences, Babol, Iran

MSc, Health Research Center, Babol University of Medical Sciences, Babol, Iran

ABSTRACT

The objective was to evaluate the effect of ergonomic education on knowledge, attitude and practice of dental stu-

dents about working body posture. In an interventional study, 50 right-handed dental students aged 20–25 years

were educated and assessed on ergonomic body posture. The participants were requested to  ll out a questionnaire

about ergonomics, before and after the education. They also frequently paid attention to their sitting posture while

treating the school children during a four-week period. Data were analyzed using chi-square, independent t-test and

paired-sample t-test at a signi cance level of P<0.05. The mean (SD) score of knowledge before and after the educa-

tion were estimated at 11.9±4.4 and 20.5±6.7, respectively. There was a signi cant difference between knowledge

scores before and after the intervention (P=0.00). No signi cant difference was found between the baseline scores of

knowledge in terms of gender, but the knowledge scores of females after the intervention were signi cantly higher

than that of the males. Knowledge scores were not signi cantly different in terms of semesters. The attitude scores

were calculated at 27.9±2.1, 28.8±1.8, respectively before and after the intervention and the practice scores were

17.2±2.2 and 18.2±2.2, respectively. These scores improved after education (P=0.03, P=0.00), with no signi cant

differences in terms of gender or semester. During the observation period, ergonomic principles were respected for

78.4±10.1%, not correlated to gender or semester. It was concluded that knowledge, attitude and practice of dental

students were improved by an ergonomic educational program.

KEY WORDS: ERGONOMICS, DENTAL STUDENTS, KNOWLEDGE, ATTITUDE, PRACTICE

814

ARTICLE INFORMATION:

*Corresponding Author: aramtirgar@yahoo.com,

sgharekhani@gmail.com

Received 28

Nov, 2016

Accepted after revision 29

Dec, 2016

BBRC Print ISSN: 0974-6455

Online ISSN: 2321-4007

Thomson Reuters ISI ESC and Crossref Indexed Journal

NAAS Journal Score 2015: 3.48 Cosmos IF : 4.006

reserved.

Online Contents Available at: http//www.bbrc.in/

Samane Gharekhani et al.

INTRODUCTION

In spite of industrialization, mechanization, develop-

ment of feasibilities and equipment, and lowering phys-

ical work-load, work-related musculoskeletal disorders

(WMSDs) are still considered to be one of the occupa-

tional health hazards (Mohammadi, et al. 2010). WMSDs

include a wide range of signs and symptoms involving

muscles, tendons and joints (Muslim, et al. 2012 ; Tirgar,

et al. 2013).This occupational disorder is a multi-factorial

phenomenon. Morphological and genetic risk factors, as

well as psycho-social and biomechanical risk factors

have a role in WMSDs (Muslim, et al. 2012; Moham-

madi, et al. 2010). Morphological and genetic factors in

terms of personal characteristics which include weight

and body mass index (BMI), etc are the main predictors

of WMSDs (Tirgar, et al. 2013).

Psychosocial risk factors such as heavy work-load,

insuf cient rest and stressful job constitute other impor-

tant predictors of WMSDs (Tirgar, et al. 2013). Biome-

chanical risk factors which are described as unfavora-

ble with prolonged statistical working posture, forceful

and repetitive motions alongside unsuitable workplace

physical conditions such as light, temperature, sound,

design of equipment, etc. were found to have greatly

in uenced WMSDs (Muslim, et al. 2012 ; Diaz-Cabal-

lero, et al. 2010; Mohammadi, et al. 2010).

Dentistry as a very  ne and precise profession is nat-

urally stressful. Dental professionals frequently suffer

from physical and psychological tensions while work-

ing. Prolonged working time, static body posture, force-

ful and repetitive motions, badly designed instruments

or workplaces alongside inevitable psychological stress

exposes them to WMSDs (Muslim, et al. 2012 ; Diaz-

Caballero, et al. 2010; Mohammadi, et al. 2010; Kariba-

sappa et al. 2014). Limited studies were conducted on

dental students to evaluate MSDs despite many docu-

mented data for dental professionals (Hayes, et al. 2009).

However, it has been reported that 64-93% of dentists

and 70% of dental students suffer from WMSDs and

moreover they are at risk of neurovascular and postural

disorders (Khan and Chew et al. 2013).

In an analytical cross-sectional study conducted

by de Carvalho et al 2009. the frequency of pain dur-

ing or after clinical work was estimated to be 76.2%

in dental students and this was signi cantly associated

with gender (de Carvalho, et al. 2009). In addition, in

an investigation conducted by Tirgar et al. on general

dental practitioners working in Babol-Iran, it was dem-

onstrated that 83.3% of dentists suffered from cervical

pain, 56.7% and 41% reported to be suffering from back

and shoulder pains (Tirgar, et al. 2015).

Ergonomics focuses on WMSDs and its causative fac-

tors such as individual and environmental risks, creat-

ing fatigue and damage to the muscular and skeletal

structures that represent some approaches to relieve the

occupational health problems

(Mohammadi, et al. 2010).

Thus, it seems that the ergonomic educational interven-

tions and provision of appropriate occupational environ-

ments and equipment based on the ergonomics princi-

ples may be effective in reducing WMSDs (Mohammadi,

et al. 2010).

Shirzaei and colleagues reported that 80.8% of dental

students were not aware of ergonomic posture during

dental procedures. They believed that dental students

with knowledge of ergonomic principals would be able

to maintain their health (Shirzaei, et al. 2015). Lewis

et al. 2001, demonstrated that the frequency and severity

of WMSDs might decrease in the video display termi-

nal users by training the ergonomic principles (Lewis,

et al. 2001). On the other hand, Karibasappa et al. (2014)

have reported that although knowledge and attitude of

quali ed dentists towards ergonomic body posture were

suf cient and proper, respectively, they did not result

in favorable behavior. They indicated that awareness

had not motivated the dental practitioners adequately

to adopt ergonomic principles (Karibasappa, et al. 2014).

In addition, Garcia et al. 2015, found no correlation

between knowledge and practice of dental student in

term of ergonomic working posture (Garcia et al, 2015).

The aim of this study was to evaluate the effect of

ergonomics educational intervention on knowledge, atti-

tude and practice of dental students of Babol University

of Medical Sciences in relation to working body posture.

MATERIAL AND METHODS

An interventional trial by ergonomic training program

was carried out on dental students (8th and 10th semes-

ters) of Babol University of Medical Sciences, Babol, Iran,

in winter, 2014 with a four-week observational period.

The study protocol was approved by the Ethics Commit-

tee of Babol University of Medical Sciences and a written

information regarding consent was obtained from each

volunteer. Also, this trial was registered in Iranian Reg-

istry of Clinical Trials website (IRCT2015041721519N3).

All the right-handed participants aged 20–25 years,

who were attending the pediatric dentistry course, were

invited for the study (n=50). Left-handed dental students

and those over 25 years of age were excluded. Prior to

training in ergonomics, the subjects were asked to com-

plete a tailored questionnaire consisting of 22 ques-

tions, with  ve response options based on the results

of previous studies, reviewed and gathered by (Muslim,

et al. 2012) in order to evaluate the knowledge, attitude

and practice of participants in relation to ergonomics in

dentistry.

BIOSCIENCE BIOTECHNOLOGY RESEARCH COMMUNICATIONS ERGONOMICS EDUCATION FOR DENTAL STUDENTS 815

Samane Gharekhani et al.

The questionnaire had  ve sections comprising demo-

graphic information (age, gender and semester), two

questions on the history of ergonomics training (previ-

ous awareness and training), eight questions on knowl-

edge about height of the dental stool, elbow level, ideal

range of upper arm abduction, bending of the neck and

trunk, positions of the upper and lower extremities and

appropriate sitting area for the right and left quadrants,

six questions on attitude (importance of awareness about

ergonomic principles, performance of educational pro-

grams, use of ergonomic equipment, four-handed den-

tistry, sitting position vs. standing, body posture of the

dentist relative to the patient) and six questions on prac-

tice (static posture, ergonomic exercise, back support,

bending of the trunk, indirect visualization of maxillary

teeth and receiving instruments without tensions). The

options related to questions involving attitude and prac-

tice were designed according to Likert scale. The face

validity of the questioner had already been con rmed

by three Dental Faculty members of Babol University of

Medical Sciences and the reliability had been assessed

by test-retest method (the Cronbach’s alpha internal

consistency coef cient = 0.926).

Then, lectures were given on Ergonomics in Den-

tistry by a trained pedodontist and the ergonomic sit-

ting posture during the restorative procedures (based on

Muslim’s study) was shown and impacted in volunteers

(Muslim, et al. 2012). The ergonomic sitting posture con-

sidered for education and evaluation in this study can be

seen in Table 1.

The same questionnaire was completed again by

the participants after four weeks. During the obser-

vation period, sitting posture of participants was fre-

quently checked by two calibrated and skillful dentists

(Kappa=0.791) by  lling out a checklist with 10 items

illustrated in Table 1, three times within one month for

each volunteer when they used dental hand pieces on

cooperative school children. The observational assess-

ment was performed for each participant at the begin-

ning of the dental procedure. The participants were not

informed when they were checked out.After collecting

data, scoring the knowledge, attitude and practice was

done before and after intervention based on the fol-

lowing method: In the knowledge section, the scores of

‘true’, ‘false’ and ‘no idea’ answers were ‘4’, ‘0’ and ‘1’,

respectively. Each question on attitude and practice was

scored from ‘1’ to ‘5’, adding up to ‘30’ based on the

degree of agreement with the ergonomic principles in

thought and behavior. In the period of observation, one

score was given to each favorable position, adding up

to 10 for work on maxillary teeth and nine for man-

dibular teeth. The mean percentage of scores of practice

was based on the observational study and recorded for

each volunteer and the mean percentage of scores of

each item on the checklist was estimated too.Statisti-

cal analyses were carried out with SPSS 18, using the

chi-squared test, independent t-test and paired-sample

t-test. Statistical signi cance was de ned at P=0.05.

RESULTS

Out of the 50 dental students participating in the study,

26 were females and 24 were males; 13 males and nine

females were in the 8th semester and 11 males and 17

females were in 10th semester. Chi-squared test revealed

no signi cant differences between different genders

or semesters (P=0.134). Prior to the study, one of the

dental students reported that he was familiar with the

ergonomics comprehensively; 34 subjects were familiar

Table 1: Ergonomic principles for sitting posture

Variable Ideal range Remarks

Height of dental stool - Should be adjusted at the level of dentist’s knees

Elbow level - The mouth positioned with maximum height of 5 cm above the elbow

Upper arm abduction <10 Should be maintained as close as possible to the trunk

Forward bending of the head <20 Eyeball movements help dentists maintain normal position of the head

Trunk rotation <20 Avoid bending trunk exceeding 60 degrees for more than 5% of the working hours

Trunk sideward inclination <10 -

Back support - To maintain the normal arch of the skeleton

Leg-knee angle 90–120 The upper extremity is parallel and the lower extremity is perpendicular to the  oor

Indirect visualization - For maxillary teeth by a dental mirror

Appropriate sitting area 9–11 O’clock 9 O’clock for the right side, 11 O’clock for the left side of the mouth

816 ERGONOMICS EDUCATION FOR DENTAL STUDENTS BIOSCIENCE BIOTECHNOLOGY RESEARCH COMMUNICATIONS

Samane Gharekhani et al.

FIGURE 1. Showing Frequency percent of ergonomic positions during the observational period.

FIGURE 2. Showing the correct and incorrect sitting postures(A: Correct, B: Incorrect).

BIOSCIENCE BIOTECHNOLOGY RESEARCH COMMUNICATIONS ERGONOMICS EDUCATION FOR DENTAL STUDENTS 817

Samane Gharekhani et al.

Table 2: Mean (SD) values of knowledge, attitude and practice before and after the

education in terms of gender.

Knowledge

Time Gender Mean SD P-value

T1 F 11.19 5.24 0.234

M 12.70 3.35

T2 F 22.69 6.80 *0.019

M 18.25 6.10

Attitude

T1 F 28.19 2.40 0.400

M 27.66 1.92

T2 F 28.84 2.16 0.860

M 28.75 1.59

Practice

T1 F 17.07 2.49 0.516

M 17.50 2.02

T2 F 18.38 2.53 0.731

M 18.16 1.83

Practice based on check list F 79.32% 10.53% 0.529

M 77.34% 9.89%

*signi cant: P<0.05 based on the independent t-test, F: female, M: male, T1: before the intervention, T2: after

the intervention

with it a little bit and 15 were not familiar with it at

all. Only nine subjects have previously been treated in

ergonomics in dentistry. The mean (SD) values of knowl-

edge before and after the education were estimated at

11.9±4.4 and 20.5±6.7, respectively. Paired-sample t-test

revealed a signi cant difference between the knowledge

scores before and after the intervention (P=0.00).

No signi cant differences were found between the

baseline scores of knowledge in terms of gender, but the

knowledge scores of females after the intervention were

signi cantly higher than those of the males (Table 2). In

addition, the semester had no effect on knowledge scores

(Table 3). Mean scores of attitude before and after the

education were calculated to be 27.9±2.1 and 28.8±1.8,

respectively. The attitude of dental students signi cantly

improved after education (P=0.03 based on the inde-

pendent t-test); however, there was no signi cant dif-

ference between the scores of attitude before and after

education in terms of the gender or semester (Tables 2

and 3).Analysis of data collected from the question-

naires by the independent t-test revealed that follow-

ing the intervention, practice scores were signi cantly

higher than those at the baseline (17.2±2.2 vs.18.2±2.2,

P=0.00). However, there were no signi cant differences

between the practice scores before and after education in

terms of the gender or semester (Tables 2 and 3).

Working and sitting postures of dental students were

totally evaluated 150 times. Mean ± SD score percentage

of practice of participants based on the observational

study was estimated at 78.4±10.1. Figure 1 illustrates the

percentage frequencies of each item of ergonomic body

posture observed by the students throughout the period

of observation. Checking out the working posture of

participants revealed no signi cant differences in terms

of the gender or semester (Tables 2 and 3). The correct

and incorrect sitting positions are shown in Figure A

and B respectively.

DISCUSSION

In the present study, education on ergonomics was

shown to be effective in the promotion of knowledge,

attitude and practice of dental students regardless of

gender or semester. It has been demonstrated that psy-

chosocial and biomechanical factors related to occu-

pational health problems can be controlled by educa-

tion. In agreement with the present study, Mohammadi

et al. (2010), reported that increasing the knowledge of

workers in relation to occupational health is the basic

factor for promoting the positive attitude and practice

(Mohammadi, et al. 2010). Stetler et al. have emphasized

818 ERGONOMICS EDUCATION FOR DENTAL STUDENTS BIOSCIENCE BIOTECHNOLOGY RESEARCH COMMUNICATIONS

Samane Gharekhani et al.

that the multi-interventional methods, including the

elimination of risk factors along with the educational

programs, might be effective in solving the problem of

MSDs (Stetler, et al. 2003).

Considering the positive effect of education in this

study (Tables 2 and 3), dental professionals should be

aware of the importance of ergonomics in dentistry and

should be encouraged to apply it while providing dental

care. Additionally, it should be emphasized that regular

exercises and breaks during working hours can decrease

the frequency and severity of various MSDs (Sharma and

Gholchha 2011). In the present observational study, the

height of the dental stool, trunk sideward inclination,

leg-knee angle and upper arm abduction were favorable

in more than 90% of the cases while back support was

observed in only 47.3% of the cases.

Unfortunately, forward bending of the head exceed-

ing favorable range or lack of back support were

observed in almost half of the cases (Figure 1). It seems

that although the students were aware of the correct sit-

ting posture, they frequently lost their correct posture

to improve visualization while working. Based on the

results of Hayes’s study, back (36.3-60.1%) and neck

(19.8-85%) pains were shown as the most common pain-

ful regions in Dentists (Hayes, et al. 2009). Also, Shaik

et al. (2011), assessed frequency of MSDs in dental sur-

geons and concluded that 83.3% and 70% respectively

suffered from back and neck pains sometimes and 73.3%

felt stiffness in back region

(Shaik, et al. 2011).

Al-Ghadir et al. (2015) have reported the lower back

(60%), neck (49%) and shoulder (49%) regions as the

most common regions with pain and fatigue (Alghadir,

et al. 2015). Recently it has been shown that the neck

and low back regions are the most common painful

body areas among dental students (Ng, et al. 2016).In

the present study, correct forward bending of the neck

was observed in 56.6% of cases. In a study conducted

by Vakili et al (2016 ) in Tehran, the prevalence of the

forward head posture was reported in 85.5%, of the par-

ticipants (Vakili, et al. 2016).

Forward bending of the neck more than 20° is consid-

ered beyond the balanced ergonomic parameters (Hoer-

ler, et al. 2012). Researchers have found a relationship

between vi sual acuity and balanced posture of dental

professionals while working (Maillet, et al. 2008). Mag-

nifying lenses are recommended to provide better visu-

alization along with maintaining a proper body posture

(Branson, et al. 2004). The  ndings of the present work

showed that indirect visualization for maxillary teeth

was observed in 75.3% of the cases. Reasonably, the use

of oral mirrors for maxillary teeth helps dentists main-

tain an ergonomic posture of neck. However, almost half

Table 3: Mean (SD) values of knowledge, attitude and practice before and

after the education in terms of gender

Knowledge

Time Semester Mean SD P-value

T1 8th 12.68 4.87 0.289

10th 11.32 4.10

T2 8th 19.72 6.67 0.448

10th 21.21 6.93

Attitude

T1 8th 27.36 2.21 0.098

10th 28.39 2.07

T2 8th 28.72 1.83 0.813

10th 28.85 1.97

Practice

T1 8th 17.36 2.46 0.820

10th 17.21 2.14

T2 8th 18.36 2.27 0.815

10th 18.21 2.18

Practice based on check list 8th 79.19% 11.55% 0.712

10th 78.01% 9.43%

*signi cant: P<0.05, T1: before the intervention, T2: after the intervention

BIOSCIENCE BIOTECHNOLOGY RESEARCH COMMUNICATIONS ERGONOMICS EDUCATION FOR DENTAL STUDENTS 819

Samane Gharekhani et al.

of the participants exhibited forward bending of head

exceeding the normal range.

Within the study limitations, lack of dexterity of dental

students and natural stress and dif culties existing while

treating the pediatric patients were considered as the

potential factors for loss of proper body posture. There-

fore, further studies on quali ed dental healthcare pro-

viders are recommended. In addition, similar studies with

follow-up periods for the long-term evaluation of ergo-

nomic body posture are recommended by the authors.

CONCLUSION

The ergonomic educational program was effective in the

promotion of knowledge, attitude and practice of dental

students in relation to working body posture.

CONFLICT OF INTEREST

The authors stated no con ict of interest.

FUNDING

The present project was  nancially supported by Babol

University of Medical Sciences.

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