Rajiv Gandhi University of Health Sciences s135

Rajiv Gandhi University of Health Sciences, Karnataka Curriculum Development Cell CONFIRMATION FOR REGISTRATION OF SUBJECTS FOR DISSERTATION

Registration No. Name of the Candidate : Ms. SUKIRTI MOHUN Address :, SDM College of physiotherapy, Dharwad. Name of the Institution : SDM College of Physiotherapy, Dharwad. :MPT (Master of Physiotherapy in Musculoskeletal Course of Study and Subject Disorders and Sports) Date of Admission to Course :JULY 2011 : A study to identify the relationship between posture and Title of the Topic musculoskeletal disorders among dentist in Hubli- Dharwad. Brief resume of the intended work : Attached

Signature of the Student :

Guide Name :DR. SUNIL K. M. Remarks of the Guide : RECOMMENDED FOR REGISTRATION Signature of the Guide :

Co-Guide Name : DR. SHARMILA DUDHANI Signature of the Co-Guide :

HOD Name : Signature of the HOD :

: DR.RAVI SAVADATTI Principal Name Principal SDMCPT Principal Mobile No. : 9845051209 Principal E-mail ID : [email protected] Remarks of the Principal :

Principal Signature :

A) BRIEF RESUME OF THE STUDY: INTRODUCTION: According to World Health Organization musculoskeletal disorder defines as “a disorder of the muscles, tendons, peripheral nerves or vascular system not directly resulting from an acute or instantaneous events.These disorder are considered to be work related when the work environment and the performance of 1 work contribute significantly, but are only one of a numbers of factors contributing to the causation of a multifactorial disease.”Dental professionals most commonly experience musculoskeletal disorder during the course of their career, if the musculoskeletal pain occur regularly then cumulative physiological damage can lead to career ending disability.The musculoskeletal disorder among dentist occur due to various risk factors which include prolonged static posture, repetitive movement, suboptimal lighting, poor positioning, mental stress, physical conditioning. Posture also play a very important role which predispose musculoskeletal disorder. Dentist assume prolonged static postures which require more than 50% of the body’s muscles to contract to hold the body in one position while resisting gravity.Since maintaining static posture or restriction of a joints due to muscles contraction for a long period of time, the production of synovial fluid decreases in the weight bearing joints this increases the friction and resulting into decrease joint range of motion. Most commonly dentist’s postures consists of forward bending. Continuous work in front of and below the operator’s eye level leads to forward head and rounded shoulder posture, this will cause weakening and elongation of the shoulder blade muscles. As a result shoulder blade tends to move away from the spine, leading to rounded shoulder posture, while the anterior mover muscles become short and tight which pulls the head forward. Repeated rotation of the head, neck and the trunk to one side causes muscles imbalance that is, one side of the muscle become stronger and shorter while the opposite muscle become weaker and elongated. As a result stressed shortened muscles can become ischemic, necrosis and painful. In seated posture dentist who are repeatedly leaning toward a patient cause muscle imbalance which tends to develop between the 2 abdominal muscles and low back muscles which causes strain and overexertion in the lower back extensors which decreases the oxygenation level in the muscles while the abdominal muscles tends to become weak resulting into the abnormal posture. Due to sustained, static muscles contraction the tendon get stretch and compress the vascular supply to the muscles and the surrounding tissues thereby resulting into depletion of a nutrient and oxygen supply.Metabolites like lactic acid gets accumulated in the muscles tissue, this process may leads to damage of muscles tissue and a painful sensation and predispose nerve compression. Spinal diskprovides movement between the vertebrae for spinal flexibility and transmit the pressure between them. When weight is applied to the disk, the nucleus pulposus expand outward,which exert pressure on the annulus fibrosus. In unsupported sitting pressure in the lumbar spinal disks increases 40% over pressure from standing. During forward flexion and rotation the pressure increases 4oo% which makes the structure vulnerable to injury.The posterior aspect of the annulus fibrosus is thin, because of repeated forward flexion nucleus pulposus push against the annulus fibrosus resulting into bulging of a disk which can press on the spinal cord or peripheral nerves causing lower back pain, hip pain or leg pain. Movement is required to nourish the nucleus pulposus, but under static and sustained pressure nutrition to the disk is diminished and leads to degenerative changes. If these physiological changes allow to persist for a long time without treatment then it will leads to significant structural damage which leads to musculoskeletal disorder. The most common musculoskeletal disorder because of prolonged static posture in dentist is low back pain, tension neck syndrome which occur due to forward head posture in which pain, stiffness and muscle spasms occur 3 in cervical musculature and most commonly pain occur in between the shoulder blades and the occiput. Operating with the arm elevated can predispose trapezius myalgia in which pain, tenderness, muscle spasms seen in the upper back on the side on which the dentist holds the mirror.These abnormal postures will facilitates the musculoskeletal disorder and over months or years these posture will adapt by the dentist not only at work but also in their leisure activities.1

The musculoskeletal disorder can be reduced by the following proper guidelines, the dentist position, sitting with maintaining low back curve, the seat should be tilted to 15degree forward to maintain low back curve this will place hips slightly higher than the knees and it increases hip angle greater than 90degree which may allow for closer positioning to the patient, the equipment use by the dentist should be within the reach to avoid twisting and turning, the patient’s operating chair should be height adjustable.It also advice for the dentist to take periodic break between the treatment sessions.2

A cross sectional study was conducted among 485 dental personnel in North –Eastern state of Malaysia in this survey prevalence of back pain was 45%3. According to Previous studies in the musculoskeletal disorder the prevalence of back pain and the neck pain were highest ranging from 45% to 59%, followed by shoulder pain around 20% to 53% and wrist and hand pain ranging from 18 to 26%. Followed by knee, feet and elbows 15% to 16%.3,4,5,6,7

In India Study was conducted in Surat showed prevalence of back pain 75.5%, neck pain 42.9%, shoulder pain 22.5%, followed by wrist and leg pain 2.04% among 400 dentists.8

4 Branson’s posture assessment instrument is used to identify the posture over 5 minute when dentist will be handling the case. It is a valid and reliable instrument (G- 0.797). Branson’s posture assessment instrument is done at 1minute, 3minute and 5minute while dentist is handling a case. It categories posture into 3components acceptable, compromised, and harmful. The intraclass correlation coefficient was found 0.95, p-value<0.001.9,10 Standardized Nordic questionnaire is also used for screening the musculoskeletal disorder among dentist and it consist of structured and multiple choice questions which is a self- administered questionnaire. Standardized Nordic questionnaire composed of general questionnaire which focus on neck, shoulder, elbows, wrist/ hand, upper back, low back, one or both thighs, one or both knees, one or both ankle/feet.The questionnaire is a valid and reliable tool.11,12

NEED FOR THE STUDY: Musculoskeletal disorder is one of the common problem among dental practitioners.It is said that around 86% of the dentist suffer from at least one or more musculoskeletal disorder in their lifetime4. Prolonged static posture and continuous repetitive task done by the dentist during treatment session is the major cause of musculoskeletal disorder1.Early diagnosis plays a role to reduce the musculoskeletal disorder symptoms along with proper ergonomic advice.2 Taking into consideration the above factors, the need arises to recognize the compromised posture adapted by the dentist and correlate them with musculoskeletal disorder. In previous studies posture was assessed using Branson’s posture assessment instrument9,10 and musculoskeletal disorders were assessed using standardized Nordic questionnaire11,12. To our knowledge none of the studies have been done to correlate Branson’s posture 5 assessment as a postural assessment tool and standardized Nordic questionnaire as a tool to assess musculoskeletal disorder. Thus, a need arises to undertake the study.

RESEARCH HYPOTHESIS: RESEARCH HYPOTHESIS;

Null hypothesis (H0): There will be no relationship between the posture and musculoskeletal disorders among dentists practicing in Hubli- Dharwad.

Alternate Hypothesis (H1):There will be a relationship between posture and musculoskeletal disorders among dentists practicing in Hubli -Dharwad.

REVIEW OF LITERATURE: A cross sectional study was done on 485 dental personnel in North-Eastern State of Malaysia they had taken Branson’s posture assessment instrument to measure the posture thereby assessing the prevalence of musculoskeletal disorder among dentist officers, dental nurses, technicians and dental surgery assistant. In this study they had found that back pain was the common musculoskeletal disorder among dental personnel and the study showed the prevalence of back pain was 45%. More than 80% of the dentists showed to have repetitive tasks, experienced abnormal posture and they were involved in excessive movements while doing their work.3 Using a randomized crossover design the study was done on twenty two dental hygiene students to assess the effect of magnification lenses on the posture. The posture was observed by Branson’s posture assessment instrument which provides a reliable method to examine posture over a period of five minute. According to this study posture of the students while 6 wearing magnification lenses was more acceptable (p=.019) than when wearing traditional safety glasses.13

A study was done to investigate if using magnification loupes improved dental hygiene student’s posture during treatment. In this study posture of a students was measured by Branson’s posture assessment instrument with and without loupes. Study showed a significant improvement in posture when using loupes.14

The cross sectional study was done on Jordanian dentist, they had recruited 200 dentists. In the study the prevalence was taken by preliminary questionnaire which was reliable and stable tool they had found 86% of the dentists suffering from atleast one or more musculoskeletal disorder and among musculoskeletal disorder the most commonly seen was back pain 56% which was more commonly seen in males, neck pain 47%, shoulder pain 39% females were more commonly affected , hand or wrist 26% hand or wrist pain was most prevalent among dentists who worked in standing, 42% of them taken medical attention and had been diagnosed by a physician followed by 8% of dentists suffering from hearing loss and 10.5% of dentists suffering from stress. According to this study neck , back, shoulder pain were significantly increased among the older age dentist and dentist who had more work experience.4

A study was done which was a cross sectional study, by self- reporting questionnaire in Queensland, Australia among 400 dentists who registered in the Queensland branch of the Australian Dental Association they had found 87.2% of the dentists have atleast one musculoskeletal disorder in 12 month period in this, study showed most common prevalence was neck pain 57.5% in which (p<0.05) more commonly reported by general dentists, and younger dentist showed (p<0.001), 7 and dentist present with less experience showed(p<0.001),then back pain 53.7% in which upper back pain was significantly seen in younger dentist followed by shoulder pain 53.3% which is more commonly seen in younger dentists. Hand pain was significantly seen in females dentists ( p<0.05).5

According to a study in New Zealand which was a nationwide postal survey conducted, they showed the prevalence of musculoskeletal disorder in the 12 months was neck pain 59%, lower back pain 57%, shoulder pain 45%, followed by one type of dermatitis 47% among 750 dentists. According to this study dentist who treated less patients per day had a higher prevalence of dermatitis type. For this study they had used a questionnaire which was pilot tested and was based on the literature review.6

In one of the questionnaire survey the study showed the prevalence of musculoskeletal disorder was 92% among 220 dentists in Poland in which the most common musculoskeletal disorder was neck pain which was 47%, lower back pain 35.1%which was more in males than in females, and more than 29% of the dentists trouble with finger and hand it had been found that females were more prone to get finger disorder, 23.3% of dentists showed hip disorder and this was significantly more often seen who did not use a rest breaks during work (p=0.004), followed by 20% of the dentists showed the mid back and also in the shoulder dentists showed 20.1%, dentists also showed wrist disorder which was 18.3%, they had found that 15 to 16% of the dentists showing knees, feet, and elbow disorder.The study also showed that because of the musculoskeletal disorder 32.3% of the dentists received rehabilitation.This study showed the certain degree of correlation between the professional speciality and the type of musculoskeletal, their location and when they occurred.The dentists 8 present with the general dental speciality reported less pain in the first three years of work (p=0.004) musculoskeletal disorder mostly reported in dentistswith the working experience of 9 to 10 years.7

According to cross sectional study among 77 dentists in Surat city pretested precoded questionnaire was used to identify the prevalence of musculoskeletal disorder. Among 77 dentists 63.6% of the dentists had atleast one type one musculoskeletal disorder either it was neck, back or shoulder or a combination of it.This study showed most common disorder were back pain 75.5%, neck pain 42.9%, followed by shoulder pain 22.5%, wrist and the leg pain showed 2.04%. Prolonged sitting posture was the most common factors 95.9% which aggravate the pain. According to this study three dentists were remained absent for one day and five dentists for more than two days because of the musculoskeletal disorder.8

In Hong Kong a study was done among 208 dentists, the self-reporting questionnaire was used which was pilot tested showed 43% of the dentists had atleast one or the other musculoskeletal disorder, most commonly low back pain and neck pain followed by 24% of the dentists suffering from allergic dermatitis because of the skin reaction to latex glove, 17% of the dentists experienced needle prick injury while working. The study showed that the government dentists showed a higher prevalenceof musculoskeletal problem.15

To identify the prevalence of musculoskeletal disorder a study was done in New South Wales among 355 dentists by the self-reporting questionnaire which was pilot tested according to this study 59% of the dentists complain of pain which was located in their trunk, specifically between the occiput and the coccyx. Females 9 more significantly reported trunk pain, 54% of the dentists reported headaches, 19% of the dentists reported pins and needle followed by 17% of the dentists reported weakness and 13% of the dentists reporting for numbness.16

A cross sectional survey was carried out in Thessaloniki, Greece among 430 dentists by the self -reporting questionnaire, they showed 62% of the dentists had atleast one musculoskeletal disorder like, disorder of back, neck, shoulder, hand/wrist in which low back pain was the most common musculoskeletal disorder which was 46% among dentists, followed by neck pain 26% and prevalence of hand/wrist is again 26%, for shoulder they showed the prevalence of 20%. The study showed age and gender were significant only for the neck pain.Working without breaks and educational level were significant factors for the shoulder pain. Family issues like living alone was a significant factors for neck and the shoulder pain. Perceived moderate or bad health was the important risk factor for chronic back pain.17

According to study done in South Eastern Nigeria 75 dentists were recruited who had working experience of 12 months they had given a self- reporting questionnaire to identify the prevalence of musculoskeletal disorder. The study showed the prevalence of neck, knees, ankle or feet and upper back pain were significantly higher amongst males than in females (p < 0.05). Among musculoskeletal disorder the prevalence of shoulder pain was more, 81.1% among dentists, this was followed by lower back pain 77.1%, neck pain and hand or wrist accounting for 74.3%, for knees, ankle or feet, upper back prevalence is 55.7%. According to the study there is statistical significant between the fields of practice and the distribution of musculoskeletal symptoms at neck, lower back and hand/ wrist.18 10 In a study conducted in Turkey among 350 members of the Turkish dental association by the use of self- reporting questionnaire which was pilot tested.According to the study 94% of the respondents reported one or more of the symptoms like headache, pain, numbness, foot and leg pain, finger weakness and body pain weakness. 29.05% of the group reported the presence of headache, 8.1% reported pain, 9.05% reported numbness, 30.95% reported foot and leg pain as the most severe symptom, 7.62% reported finger weakness, similarly 7.62% reporting of total body weakness. Among members 63.07% took medications for their symptoms. 84% of the respondent reported one or more of the musculoskeletal disorder like 12.87% of the group reported presence of neck pain , 9.9% of the group reported low back pain, 5.94% reported in thorax or lumbar, 14.85% reported pain in the neck and lower back, 6.93% reported pain in the arms and legs, 49.51% reported trunk pain. The feature of trunk pain was significantly different. The majority about 81.58% described their neck pain as pain, about 12.5% described pain in low back as numbness, 11.76% mentioned their pain in thorax or lumbar as needle and around 8.57% reported pain in neck and lower back as weakness.19

A cross sectional study was done in Shiraz, Southern Iran among 90 dentists in which 82 were the respondent in that 49% were males and 51% were females.With the help of self- reporting questionnaire the study was conducted. In 66 dentists pain started after employment as a dentist. Around 59 dentists had more pain during work, 27 of the dentists complained of low back pain , 23 dentists reported of having neck pain and 10 dentists mentioned about combination of back and neck pain. Of these 60 dentists who complained of pain in that, 27 of the dentists had radicular pain and 28 11 dentists felt numbness or paraesthesia in the limbs. Around 27 dentists attributed their pain because of carrying heavy objects, direct trauma and sudden rotation. 19% of the dentists who had pain went for the physiotherapy treatment. About 28% of the dentists received medications.20

According to study on final year dental students in Ismailia the musculoskeletal disorder was common among students. They had taken a self- reporting Standardized Nordic questionnaire and the self- perception of the stress level was assessed on 3-point likert scale. Among 126 dentists 66.7% of the dentists were respond the study showed in 12 months of prevalence most commonly, musculoskeletal disorder reported by the dentist was at the neck. About 64.3% of the dentists had neck pain and almost two third of it reported that their pain lasted for more than 2 days. Over 53.1% experienced neck pain which affect their daily life while 30.9% report that they had to take medical treatment. 57.9% of the dentists reported lower back pain, over two third of the dentists 67.1% had lower back pain which was last for more than 2 days. While 48% had experienced lower back pain which is sufficient to affect their daily life, and 37% of the dentists had taken the medical attention. Apart from this shoulder pain was the third highest prevalence, indicating that 48.4% of the dentists experienced pain from past year. 65.6% of those reported that their pain lasted for more than two days. 54.1% of the dentists had pain that affect their daily life and 37.7% required medical treatment.While 12.7% of the dentists reported pain in the ankle or feet and 81.3% of them reported that pain lasted more than 2 days and 78.5% reported that because of pain their daily life is affecting.21

Standardized Nordic questionnaire is used for the 12 analysis of musculoskeletal disorders. It is a self -administered questionnaire. The Standardized Nordic questionnaire is tested for its validity and reliability for musculoskeletal disorders. The reliability of the questionnaire has been shown to be acceptable. It was found that Standardized Nordic questionnaire having kappa coefficient 0.74 to 0.80 that is 0.77. The sensitivity was excellent in all situation from 82.3 to 100%. The specificity was 51.1% to 82.4%.10,11

OBJECTIVES OF THE STUDY:  To determine the relationship between posture and musculoskeletal disorders among dentists.

SOURCE OF DATA COLLECTION: Practicing dentists in Hubli and Dharwad. b) PROCEDURE, MATERIALS AND METHODS:

STUDY DESIGN: Cross sectional survey.

METHOD OF COLLECTION OF DATA:

MATERIAL : 1. Data collection sheet. 2. Standardized Nordic questionnaire. 3. Branson’s posture assessment instrument.

INCLUSION CRITERIA:

13 1. Dentist having working experience of atleast 12 months duration. 2. All specialities of dental department.

EXCLUSIÓN CRITERIA: 1. Congenital musculoskeletal disorder. 2. Rheumatoid arthritis. 3. Previous surgeries. 4. Pregnancy.

STUDY DURATION: 1 year

SAMPLE SIZE:66 ( As per the data available from Indian Dental AssociationHubli)

FORMULA: PROCEDURE: The ethical clearance is obtained from SDM College of Medical Science and Hospital. The list of the dentists doing private practice in Hubli- Dharwad is taken from Indian Dental Association Hubli. The dentists will be contacted personally and requested to participate in the study after explaining them about the study their informed consent will be taken. They will be given a general data sheet which has ademographic data, years of work experience, hours of practice in a day, their dominance, their height and weight. The dynamic posture will be assessed using Branson’s posture assessment instrument,while the dentist is treating their patients. This evaluation is done where therapist is standing at 8 o’clock and 12 o’clock position. The level of hips, trunk movement front and back, side to side rotation, head and neck movement, front and back, side to side rotation, shoulder level and the wrist position is evaluated by using a protractor scale by observational method. The evaluation is done at 1minute, 3minute, and 14 5minute. The point scoring obtained in each of the categories will be added up to obtain the final score. Depending on the score they are categorized into acceptable ( score 10 to 40), compromised ( score 41 to 80), harmful (score 81 to 194).9,10 The Standardized Nordic questionnaire will be given and they will be explained about how to fill the questionnaire. The Standardized Nordic questionnaire has three categories which tells the duration of the musculoskeletal symptoms by defining the musculoskeletal disorder symptoms as (a) pain in past 12months (b) pain in past 12months which is prevent from doing normal working (c) had pain at any time during last 7 days in the following neck, shoulder, elbows, wrist and hand, upper back, lower back, one or both hips/ thighs/buttocks, one or both knees, one or both ankle/feet.11,12

STATISTICAL TEST: After collection of data will be analyzed by chi – square test of significance. A significance is set at 5% level (p< 0.05).

OUTCOME MEASURE: 1. Branson’s posture assessment instrument. 2. Standardized Nordic questionnaire for musculoskeletal disorder.

DOES THE STUDY REQUIRE ANY INVESTIGATION OR INTERVENTION TO BE CONDUCTED ON PATIENTS OR OTHER HUMANS OR ANIMALS? IF SO DESCRIBE BRIEFLY -

HAS ETHICAL CLEARANCE BEEN OBTAINED BY YOU–yes.

15 c) LIST OF REFERENCES: 1. Bethany Valachi, KeithValachi.Mechanisms leading to musculoskeletal disorder in dentistry. American dental association. October 2003; volume 134.

2. Bethany Valachi, Keith Valachi. Preventing musculoskeletal disorder in clinical dentistry.American dental association. December 2003;volume 134.

3. Razan Abdul Samat,MohdNazriShafei, Nor AzwanyYaacob,AzizahYusoff. Prevalence and associated factors of back pain among dental personnel in North –Eastern state of Malaysia. International Journal of Collaborative Research on Internal Medicine & Public health July 2011; vol.3: No.7.

4. Nicola H. Barghout,Rola Al- Habashneh,Mahmoud K. AL- Omiri. Risk factors and prevalence of musculoskeletal disorders among Jordanian Dentists. Journal Med J 2011; vol.45, (2):195-204.

5. PA Leggat, DR Smith. Musculoskeletal disorders self- reported by dentist in Queensland, Australia. Australian Dental Journal 2006;51:4.

6. K.M.S. Ayers, W.M. Thomson, J.T. Newton ,K.C.Morgaine and A.M. Rich. Self- reported occupational health of general dental practitioners. Occupational Medicine 2009;59:142-148.

7. Anna Kierklo, AgnieszkaKobus, MalgorzataJawarska, BartlomiejBotulinski. Work-related musculoskeletal disorder among dentist- A QUESTIONNAIRE SURVEY. Ann Agric Environ Med 2011;18: 79-84.

8. SumitMoradia,Prakash Patel. A study on occupational pain among dentist of Surat city. National Journal of community medicine 2011; volume 2: issue 1.

16 9. Bonnie G. Branson, Karen B. Williams; Kimberly Krust Bray, Sandy L. Mcllnay, Diana Dickey . Validity and reliability of a dental operator posture assessment instrument (PAI).journal of dental hygiene, 2002;Volume 76: issue 4 fall.

10. BG.Branson, Karen B.Williams, Kimberly Krust Bray, Sandy L.Mcilnay, Diana Dickey. Validity and reliability of a dental operator posture assessment instrument. Journal of Dental Hygiene,2002:1-6.

11. Alexis Descatha ,Yves Roquelaure , Jean – Francois Chastang , Bradley Evanoff , Maria Melchior , Camille Mariot , Catherine Ha , Ellen Imbernon, Marcel Goldberg ,Annette Leclerc.Validity of Nordic style questionnaire in the surveillance of upper limb work related musculoskeletal disorder. Scand J work Environ health 2007 february;33(1):58-65.

12. I.Kuorinka, B.Jonsson, A.Kilbom,H.VinterbergSorensen,G.AnderssonK. Jorgensen.Standardised Nordic questionnaires for the analysis of musculoskeletal symptoms. Applied Ergonomics 1987; 18.3: 233-237.

13. B.G. Branson et al. Effect of magnification lenses on student operator posture. Journal of Dental Education volume 68: number 3.

14. J.PeggyMaillet et al, Effect of magnification loupes on Dental Hygiene student posture. Journal of Dental Education,January 2008; volume72:number1.

15. Thomas Ka- Lun Li, Edward Chin- Man Lo, Anthony Ho-Hang Wong, Wai-Hung Mok, Jenny Lai- Kuen Leung. Self- reported occupation- related health problems in Hong Kong dentist. Hong kongDental Journal, June 2006;Volume 3 no1: 39-44.

16. E.D. Marshall, L.M. Duncombe, R.Q.Robinson, S.L.Kilbreath. Musculoskeletal symptoms in New South Wales dentist. Australian Dental Journal 1997;42(4):240-6.

17 17. Evangelos C Alexopoulos, Ioanna- Christina Stathi ,FotiniCharizani. Prevalence of musculoskeletal disorders in dentist. BMC musculoskeletal disorders 2004;5:16 doi:10.1186/1471-2474-5-16

18. C.I. Udoye,E.N.Aguwa. Musculoskeletal symptoms a survey amongst a selected Nigerian dentists. The internet Journal of dental science. 2007; volume number 1.

19. Z.Polat , S. Baskan , S.Altun , I.Tacir. Musculoskeletal symptoms of dentist from South-East Turkey.Biotechnol. &Biotechnol. EQ.21/ 2007/1

20. N Pargali, N Jowkar. Prevalence of musculoskeletal pain among dentist in Shiraz, Southern Iran.April 2010; volume 1: number 2.

21. AymanEkramFahim. Factors affecting musculoskeletal disorders among final year dental students in Ismailia. The Egyptian Journal of Community Medicine January 2011;29:1.