Prevalence and risk factors for musculoskeletal disorders in dentists

Keywords: back pain, ergonomic measures, musculoskeletal pain, neck pain

Introduction Working in dental practice requires clear working field and easy access to all parts of oral cavity. For this reason, dentists often take non-physiological positions during treatment increasing the risk for musculoskeletal disorders. The aim of this study was to determine the prevalence of musculoskeletal disorders in dentists with different work experience in Novi Sad. 

Material and Methods

The study included 89 dentists. Data related to musculoskeletal disorders was collected using a questionnaire. Potential risk factors for musculoskeletal disorders were detected and analyzed. Results Out of 89 dentists, 32 (36%) were male and 57 (64%) were female. Musculoskeletal disorders were detected in 62 dentists (69.7%). 50% of dentists reported pain during first three years of work in the office, while others noted these problems later. 49 dentists (77.8%) reported increasing pain during the day. Of the total respondents, 76.2% had pain in neck, 71.4% reported discomfort in the upper part of their back, 68.3% in the region of shoulder, and 65.1% complained for pain in lower back. Lower prevalence of pain was found in the region of wrists and hands, hips, knees, ankles and elbows. Statistical analysis did not show significant difference between observed risk factors. 

Conclusion

The prevalence of musculoskeletal disorders in examined dentists in Novi Sad was 69.7%. It was higher in male compared to female respondents. Most dentists had musculoskeletal disturbances in the region of neck, shoulders and upper back. 

INTRODUCTION

Ergonomics is word of Greek origin: ergo means "to work", and nomos means "natural laws or systems" [1]. Therefore, ergonomics is defined as a science that studies "man in relation to his work environment and adaptation of devices and general conditions that should fit the individual so he could give a maximum of effective working" [1]. 
Long dental interventions require good concentration, clear working field and good access to all parts of oral cavity. They require demanding positions during work where dentists are in high risk of developing musculoskeletal disorders [1,2,3]. These problems affect muscles, joints, tendons, ligaments and nerves from foot to neck. Symptoms range from discomfort, weaker or stronger pain to more serious medical conditions that result in different social and economic consequences. These are reduced quality of dental services, frequent absence from work or even quitting the profession [2,4]. Some studies have found that musculoskeletal disorders are the most common reason for early retirement of dentists [5]. 
Most common symptoms are pain in back, where the most affected parts are lumbar and cervical spine [2,6], followed by neck and shoulders. In addition, dentists may also experience discomfort and pain in hands. Factors contributing to the pain in back and neck are: spine shape, aging, weak muscles, exercise or lack of exercise, types of movements performed, techniques of elevating items and mechanical load [2]. Aggravating factors are: excessive tilting and turning neck, leaning forward from waist, lifting shoulders and associated tilting back and neck [2,6]. First studies on this topic that have been conducted in 1980 [2] suggested high prevalence of back pain among dentists. Thus, in Denmark 60% of the investigated dentist had pain in their back, the percentage was 62.2% in Toronto, and Australia 59% [2]. 
The aim of this study was to determine the prevalence of musculoskeletal disorders in dentists with different work experience in Novi Sad. 

MATERIALS AND METHODS

The study included 89 dentists from Novi Sad. In order to collect data about the prevalence of musculoskeletal disorders among clinicians the "Standardized Nordic questionnaire for the analysis of musculoskeletal symptoms" was used [4,6]. In addition to the standardized questionnaire, a few more questions were added [2,4,6]. These questions were related to gender of examined dentists, age, work experience, work conditions (such as the length and frequency of interventions), number of treated patients per day, working hours, body position during work, position in relation to patient, sitting or standing position during work, mostly performed procedures (endodontic treatment, cavity preparation and filling placement, tooth extractions, oral surgery and therapeutic procedures in the field of dental prosthetics or orthodontics), having breaks during work or work without breaks, presence of musculoskeletal disorders and history of these problems. Questions are formulated in order to determine conditions in which respondents work. 
All collected data was analyzed using SPSS version 14.0 (SPSS Inc., Chicago, IL, USA). Obtained results were expressed as percentages and frequencies [4,6]. 

RESULTS

Out of 89 dentists surveyed, 36% were male and 64% female. Of male dentists, 75% had musculoskeletal disorders, while in female, the percentage was lower (66.7%), but with no statistically significant difference. In males, the highest percentage of complaints was registered in neck (83%), upper back (75%) and shoulders (70%) while the lowest percentage was in the region of elbows (25%) and feet (12%). In women, the highest percentage of complaints was also noted in neck (71.8%), followed by the upper back (69.2%) and shoulders (66.7%). The least discomfort was in the region of feet (20%) and elbows (7%) (Table 1). Discomfort in musculoskeletal system had 69.7% of respondents. In male respondents, pain was present in 75% of cases while in women it was 66.7%. There was no statistically significant difference in the occurrence of pain between male and female respondents. In young adults (25-35 years) symptoms were present in 67% of cases, similar results were observed in the age group 36-45 years, as well as in the category of 46-55 years. Dentists older than 56 years complained in 80% of cases (Graph 1). However, there was no statistically significant difference in the occurrence of musculoskeletal pain in patients of different age. 
One half of respondents noticed musculoskeletal pain in the first three years of employment. Dentists with 10 years, 10 to 20 years, and more than 20 years of work experience showed symptoms in 60% of cases. There was no statistically significant difference in the occurrence of musculoskeletal pain in patients with different work experience (Graph 2). 
Most dentists surveyed (77.5%) worked five days a week. Number of working hours per day ranged from 1 to 12 hours. Of the total respondents, 28.1% had a working time of 8 hours per day and 20.2% of dentists worked 6 hours per day. The most common positions of dentists were on "8 hours" (61.8%) and "10 hours" (15.7%). The highest percentage (95%) of dentists who reported problems were in the group of those who had more than 20 patients (Graph 3). Of the total number of dentists, 29.2% were mostly seating during work, and they complained in 70% of cases. 30.3% of dentists were working in standing position and they reported similar number of complaints (70%). However, most dentists (40.4%) changed their position during work and they had complaints in the highest percentage (about 80%) (Graph 4). 
The most frequent intervention was cavity preparation and restoration placement (61.4%). Breaks during work had 62.9% of respondents, while 37.1% of dentists performed therapeutic procedures without any break. 65.2% dentists had an assistant whereas 34.8% worked without an assistant. 
Average height of investigated dentists was 173.87 cm, with a standard deviation of 10.26 cm. The median was 172; meaning that 50% of respondents had height of 172 cm or less, and 50% had 172 cm or more. The percentage of dentists that had painful symptoms was approximately the same (75%) at different heights. T-test showed no statistically significant difference in the occurrence of muscular and skeletal pain in patients of different heights (Graph 5). 
According to the standardized Nordic questionnaire, the greatest number of dentists (76.2%) had pain in neck, shoulders (68.3%), and wrists (49.2%) while the lowest prevalence of pain was in elbows (12.3%) (Graph 6). 

DISCUSSION

Standardized Nordic questionnaire for the analysis of musculoskeletal symptoms used in the present study is an internationally recognized evaluation questionnaire [4,6]. The prevalence of musculoskeletal pain among dentists was 62%. Similar prevalence was found in Denmark (59.4%), while slightly higher prevalence was obtained in Taiwan (92.4%) and Southern Iran (80%) [3,4,6]. 
Some authors have shown that the occurrence of pain in dentists is related to their work experience, age, and number of treated patients per day. It can also be related to dentists' height [3,4]. The current study showed that number of treated patients per day is an important risk factor for the occurrence of pain. 
In the present study, 76.2% of dentists had pain in neck, 71.4% in upper back and 68.3% in shoulders. These results differ from results of the study conducted in Taiwan, which showed the highest prevalence of pain in shoulders 75.1%, followed by 71.6% in neck and lower back 66.5% [4]. 
Research conducted among dental hygienists showed that it takes about 6 years of work experience to start feeling symptoms in upper extremities. This could be explained by the influence of microtrauma that causes changes even before an individual has symptoms [7]. 
Some researchers have shown that most dentists work in sitting position, on the right side of the patient, where the patient's mouth is the center while dentist may be in the position on "8 hours" or "11 hours" in relation to the center. From an ergonomic standpoint, dentists should work in the position on "12 hours" in relation to the patient. This position, in addition to the consideration that it is the most ideal, reduces the need for lifting arms and shoulders and allows enough approximation to the patient without mechanical obstacles posed by dental chair [8]. The most convenient dental chairs are with narrow backrest which reduces need for exaggerated hand lifting and tilting of therapist [8]. Kilpatrick (1971) showed that dentists who have an assistant are up to 16-17% more efficient and have significantly reduced stress and fatigue [5]. Benefits of working with an assistant are: faster and more efficient intervention as well as preservation of health of dentists. Working with an assistant means that dentist would be able to An usual posture that one dentist takes during work is extreme flexion of head and neck with shoulders bent forward. This position may cause shortening of sternocleidomastoid, scalene, serratus anterior and pectoralis minor muscles, while middle and lower fibers of trapezoid muscle can be elongated to adapt to this condition. Such muscle imbalance may play a role in the onset of chronic non localized pain [9,10]. Another muscular imbalance is present in shoulders, caused by exaggerated strengthening of deltoid and supraspinatus muscles. These muscles are in many cases overdeveloped in dentists, because of frequent positions with elevated arms at some distance from the body. Such muscle imbalance can cause irregular movements in shoulder joint accompanied by tendon pain [11]. Muscular imbalance between abdominal muscles and lower part of back can cause more problems. Repeated tilting to the patient with bent back can cause fatigue in superficial extensors of the lower part of back, while deep abdominal muscles (tranvsersus abdominis and obliquus abdominis muscles) may become weak [11]. 
For prevention of musculoskeletal disorders in dentists, ADA (American Dental Association) recommended stretching wrists and fingers, particularly between the thumb and forefinger. During dental treatment, elbows and/or forearms should be resting on chair, to stabilize dentist's hand [1]. Main body and shoulder muscles are designed to provide solid and stable base for arm movements. Strengthening of these muscles is the main purpose of Pilates. Pilates is an exercise program that may contribute to musculoskeletal health of dentists. It considers the use of light loads and large number of repetitions. Muscle strengthening exercise should be performed three times a week, with a break of one day between workouts. Exercising should begin with a minimum number of training and repetition that will increase over time [2]. 
An ideal position to work in office would be: neck flexion 0-10 degrees without rotation and tilting to the side, shoulders relaxed to the side, elbows in the level of patient's mouth and in flexion of about 90 degrees, while the lower part of back supported by abducted feet rotated outward. Feet should lie on the floor [10]. 
From the standpoint of ergonomics, dentist's chair is essential in the office [14]. The chair should maintain body of dentist in neutral position. The backrest with its convexity should maintain natural lumbar lordosis when sitting; therefore it is called lumbar support. Lumbar support should be about 20 cm in height and thickness of 3-5 mm, convex from top to bottom; to mimic natural lordosis of dentist's back. If thicker, it could cause increased pressure on lumbar vertebrae. On the other hand, large backrests must not cause pressure on the chest part of the spine and should not push it forward. All backrests that exceed lower edge of scapula may reduce benefits of lumbar supporters; therefore, they should be about 6 cm below the lower edge of scapula. Wide backrest should be avoided because they may interfere with the movement of spine as well as lateral movements of arms and shoulders [14]. Chairs for therapists without backrests are also considered ergonomic because when sitting in these chairs, pelvis is approximately in neutral position, as in saddle or while standing. Such position of pelvis helps to balance the spine in various movements; however, this chair design allows increasing pressure on peritoneal region [14]. Many studies have confirmed that armrests are used in the prevention of pain in neck, shoulders and lower back by reducing muscle activity, especially of upper fibers of trapezoid muscle of dominant hand. Armrests should be highly adjustable to support the dentist in neutral position. Well adjusted armrests can prevent pain in neck and shoulders. Armrests reduce activity of rhomboid, and thoracic and cervical part of errector spinae muscles [14,15]. Due to the nature of their work, dentists cannot always maintain adequate contact with lumbar supporters and must tilt slightly forward for good view of certain surfaces of teeth. Pressure on discus between vertebrae is the strongest in this position, therefore it is very important that dentist learns how to properly stabilize and protect lower back with his muscles-primarily transverse abdominal muscles. When used properly, these muscles by their action reduce pain in lower back [14]. 
Besides location, other risk factors are length and duration of intervention. It has been shown that even low level of load if it lasts for long time can cause muscle fatigue and chronic pain [2]. Some studies suggest a break of 10 minutes during an intervention [4]. A number of short breaks during working hours (not longer than 5 seconds) are much more comfortable and provide complete recovery of tired muscles. During these micro-pauses tensed muscles get more blood and time to recover [10]. Since static positions must be avoided it would be good from time to time to adjust backrests and seat, so that the load is transmitted from tissue to tissue and micro trauma minimized [5]. 
Dentistry involves handling small instruments, vibrating instruments and performing repetitive actions [1,10]. It is proved that there is a clear difference in the effort of right and left hands, dominant and non-dominant hand during dentists' work. Work using dominant hand requires extremely fine motor coordination since manual and electrical instruments are used with this hand. In addition, sometimes this hand is holding syringe, saliva ejector and mirror. Non-dominant hand is mainly used to assist -get clear working field, control the movements of tongue and cheeks, or take liquid out of oral cavity. This requires static and sometimes very strong hand grasp so that both hands are exposed to static load, although with different roles [16]. When choosing hand instruments, larger diameter of handles should be chosen, because in this way the pressure is transferred to larger group of muscles [16]. 

CONCLUSION

The prevalence of musculoskeletal disorders in surveyed dentists in Novi Sad was 69.7%. They were more pronounced in males than females. Most of respondents reported musculoskeletal disorders in neck, shoulders, and upper of back. Since the prevalence of musculoskeletal disorders was high, it is necessary to implement better training of dentists and dental students about causes and methods for prevention of these problems. 

NOTE

Research results presented in this paper are the part of research carried out within the project "Research and development of methods for modeling and fabrication of dental restorations using modern technology and computer supported systems" -TR035020, funded by the Ministry of Science and Technological Development of the Republic of Serbia. 

UVOD

Reč "er go no mi ka" po ti če od grč kih re či er go, što zna či "ra di ti", i no mos, ko ja pod ra zu me va pri rod ne za ko ne ili si ste me [1]. Sto ga je er go no mi ka de fi ni sa na kao na u ka ko ja pro u ča va "čo ve ka u od no su na nje go vo rad no okru že nje, od no sno adap ta ci ju uređa ja i uop šte uslo va ko ji tre ba da od go va ra ju po je din cu ka ko bi on mo gao bi ti mak si mal no rad no efi ka san" [1]. 
Če ste du go traj ne sto ma to lo ške in ter ven ci je zah te va ju dobru kon cen tra ci ju, pre gled no rad no po lje i do bar pri stup svim de lo vi ma usne du plje. Ovo, na rav no, pod ra zu me va i zah tev ne po lo ža je te la te ra pe u ta to kom ra da, zbog če ga su sto ma to lo zi iz lo že ni vi so kom ri zi ku od na stan ka mi šić no-ske let nih te go ba [1,2,3]. Ove te go be po ga đa ju mi ši će, zglo bo ve, te ti ve, li ga men te i ner ve od sto pa la do vra ta. Simp to mi va ri ra ju od ne la god no sti, sla bih, od no sno ja kih bo lo va, do te žih zdrav stve nih sta nja ko ja iza zi va ju so ci jal ne i eko nom ske po sle di ce. One pod ra zu me vaju sma njen kva li tet sto ma to lo ških uslu ga, če sta od su stvo va nja s po sla ili čak na pu šta nje pro fe si je [2,4]. Ne ke stu di je na vo de mi šić no-ske let ne po re me ća je kao naj če šće raz lo ge pre vre me nog pen zi o ni sa nja sto ma to lo ga [5]. 
Naj če šći simp to mi su bo lo vi u le đi ma, gde su pr ven stve no po go đe ni lum bal ni i cer vi kal ni deo kič me [2,6], a za tim sle de vrat i ra me na. Po red to ga, sto ma to lo zi mo gu ose ti ti i te go be u vi du bo la u ru ka ma. Fak to ri ko ji do pri no se bo lu u le đi ma i vra tu su: ob lik kič me nog stu ba, sta re nje, sla bi mi ši ći, ve žba nje, odno sno iz o sta nak ve žba nja, vr ste po kre ta ko ji se iz vo de, teh ni ke po di za nja pred me ta i me ha nič ka op te re će nja [2]. Ote ža va ju ći fak to ri su: pre te ra no na gi nja nje i okre ta nje vra ta, na gi nja nje na pred iz stru ka, po di za nje ra me na i udru že no na gi nja nje i le đa i vra ta [2,6]. Pr va is tra ži va nja na ovu te mu, za po če ta oko 1980. go di ne [2], go vo re u pri log vi so koj pre va len ci ji bo la u le đi ma me đu sto ma to lo zi ma. Ta ko je u Dan skoj 60% is pi ti va nih sto ma to lo ga ima lo bo lo ve u le đi ma, u To ron tu 62,2%, a u Austra li ji 59% sto ma to lo ga [2]. Cilj ovog ra da je bio da se utvr di pre va len ci ja mi šić no-ske letnih te go ba kod sto ma to lo ga s raz li či tom du ži nom rad nog sta ža na te ri to ri ji No vog Sa da. 

MATERIJAL I METODE RADA

Is tra ži va nje je ob u hva ti lo 89 sto ma to lo ga ko ji ra de na te ri to ri ji No vog Sa da. U ovom is tra ži va nju ko ri šćen je "Stan dar di zo va ni nor dij ski upit nik za ana li zu mi šić no-ske let nih simp to ma" ra di pri ku plja nja po da ta ka o pre va len ci ji mi šić no-ske let nih simp toma kod sto ma to loga [4,6]. Kao do da tak ovom upit ni ku po stavlje no je još ne ko li ko pi ta nja [2,4,6]. Ona su se od no si la na: pol is pi ti va nih sto ma to lo ga, sta rost i du ži nu rad nog sta ža, uslo ve u ko ji ma ra de (tra ja nje i uče sta lost in ter ven ci ja), broj pa ci je na ta dnev no, du ži nu rad nog vre me na, po lo žaj te la za vre me ra da, po lo žaj sto ma to lo ga u od no su na pa ci jen ta, se de ći ili sto je ći po lo žaj za vre me ra da, naj če šće pri me nji va ne te ra pij ske po stupke (en do dont ski tret man, pre pa ra ci ja ka vi te ta i po sta vlja nje ispu na, eks trak ci ja zu ba, oral no hi rur ške in ter ven ci je, te ra pij ski za hva ti iz obla sti sto ma to lo ške pro te ti ke ili or to pe di je vi li ca), pra vlje nje pa u za to kom ra da, po sto ja nje mi šić no-ske let nih tego ba i isto ri ju ovih te go ba. Pi ta nja su for mu li sa na i po sta vlje na ka ko bi se usta no vi li uslo vi pod ko jim is pi ta ni ci ra de. 
Svi pri ku plje ni po da ci su ana li zi ra ni pri me nom SPSS, verzi je 14.0 (SPSS Inc., Chi ca go, IL, USA). Do bi je ni re zul ta ti su iz ra že ni u fre kven ci ja ma i pro cen ti ma [4,6]. 

REZULTATI

Od ukup no 89 is pi ta ni ka, 36% sto ma to lo ga je bi lo mu škog, 64% žen skog po la. Me đu mu škar ci ma 75% je ima lo mi šić no-ske let ne te go be, a me đu že na ma 66,7%, ali ova raz li ka ni je bi la sta ti stič ki zna čaj na. Kod sto ma to lo ga mu škog po la naj ve ći pro ce nat te go ba za be le žen je u pre de lu vra ta (83%), po tom u gor njem de lu leđa (75%) i ra me ni ma (70%), a naj ma nji u pre de lu lak to va (25%) i sto pa la (12%). Kod sto ma to lo ga žen skog po la naj ve ći pro ce nat te go ba bio je ta ko đe u pre de lu vra ta (71,8%), po tom u gor njem de lu le đa (69,2%) i ra me ni ma (66,7%), dok su naj ma nje te go ba že ne ose ćale u pre de lu sto pa la (20%) i lak to va (7%) (Ta be la 1). 
Te go be u mi šić no-ske let nom si ste mu ima lo je 69,7% is pi tani ka. Bol je za be le žen kod 75% mu ška ra ca i 66,7% že na, ali razli ka ni je bi la sta ti stič ki zna čaj na. Me đu mla dim sto ma to lo zi ma (25-35 go di na) te go be su za be le že ne u 67% slu ča je va, a slič ne vred no sti su uoče ne i u sta ro snoj gru pi 36-45 go di na, od no sno 46-55 go di na. Kod sto ma to lo ga sta ri jih od 56 go di na te go be su re gi stro va ne u vi še od 80% slu ča je va (Gra fi kon 1). Sta ti stič ki zna čaj ne raz li ke u po ja vi mi šić no-ske let nog bo la kod is pi ta ni ka raz li či te ži vot ne do bi ni je bi lo. 
Po lo vi na is pi ta ni ka je mi šić no-ske let ni bol ose ti la u pr ve tri go di ne po za po sle nju. Kod sto ma to lo ga sa rad nim sta žom do 10 go di na, onih sa sta žom iz me đu 10 i 20 go di na, kao i onih ko ji ra de du že od 20 go di na, te go be su uoče ne u vi še od 60% slu ča je va. Ni je utvr đe na sta ti stič ki zna čaj na raz li ka u po ja vi mi šić no-ske let nog bo la kod is pi ta ni ka s raz li či tom du ži nom rad nog sta ža (Gra fi kon 2). 
Ve ći na sto ma to lo ga (77,5%) ra di la je pet da na u ne de lji. Broj rad nih sa ti dnev no va ri rao je od jed nog sa ta do 12 sa ti. Osam sati dnev no ra di lo je 28,1% sto ma to lo ga, a šest sa ti dnev no 20,2% is pi ta ni ka. Naj če šće po zi ci je to kom ra da u od no su na pa ci jen ta bi le su po zi ci ja na "8 sa ti" (61,8%) i "10 sa ti" (15,7%). Čak 95% sto ma to lo ga s te go ba ma bi lo je u gru pi onih ko ji su ima li vi še od dva de set pa ci je na ta dnev no (Gra fi kon 3). 
To kom ra da je pre te žno se de lo 29,2% sto ma to lo ga, a kod njih su za be le že ne te go be u sko ro 70% slu ča je va, dok je to kom ra da 30,3% sto ma to lo ga sta ja lo, a pro ce nat re gi stro va nih te go ba me đu nji ma bio je isti (70%). Ipak, naj vi še sto ma to lo ga (40,4%) me nja lo je na čin ra da i kod njih su te go be za be le že ne u ve ćem pro cen tu (oko 80%) (Gra fi kon 4). Naj če šći za hva ti bi li su pre pa ra ci ja ka vi te ta i po sta vlja nje ispu na (61,4%). Pa u ze to kom ra da pra vi lo je 62,9% sto ma to lo ga. Sa asi sten tom je ra di lo 65,2% sto ma to lo ga. 
Pro seč na vi si na is pi ti va nih sto ma to lo ga bi la je 173,87 cm, sa stan dard nom de vi ja ci jom od 10,26 cm. Me di ja na je bi la 172 cm. Pro ce nat sto ma to lo ga sa bol nim te go ba ma bio je pri bli žno isti (75%) kod is pi ta ni ka raz li či te vi si ne. Stu den tov t-test ni je po ka zao sta ti stič ki zna čaj nu raz li ku u po ja vi mi šić no-ske let nog bo la kod is pi ta ni ka raz li či te vi si ne (Gra fi kon 5). 
Pre ma stan dar di zo va nom nor dij skom upit ni ku, naj ve ći broj is pi ti va nih sto ma to lo ga ose tio bol u vra tu (76,2%), po tom u rame ni ma (68,3%) i ruč nim zglo bo vi ma (49,2%), dok je naj ma nja pre va len ci ja bo la bi la u lak to vi ma (12,3%) (Gra fi kon 6). 

DISKUSIJA

Stan dar di zo va ni nor dij ski upit nik za ana li zu mi šić no-ske let nih simp to ma je me đu na rod no pri znat upit nik za pro ce nu ste pe na mi šić no-ske let nih te go ba [4,6] i pri me njen je u na šem is traži va nju. Pre va len ci ja mi šić no-ske let nog bo la me đu is pi ta nim sto ma to lo zi ma bi la je 62%. Slič na sto pa pre va len ci je utvr đe na je u Dan skoj (59,4%), dok su ne što ve će sto pe pre va len ci je za bele že ne u Taj va nu (92,4%) i Ju žnom Ira nu (80%) [3,4,6]. 
Ne ki auto ri su po ka za li da na po ja vu bo la uti ču du ži na radnog sta ža, sta rost sto ma to lo ga, od no sno broj pri mlje nih pa ci-je na ta u to ku da na. Na pre va len ci ju bo la ta ko đe mo že da uti če te le sna vi si na sto ma to lo ga [3,4]. U na šem is tra ži va nju se poka za lo da je broj dnev no le če nih pa ci je na ta va žan fak tor ri zi ka za po ja vu bo la. 
Bol u vra tu ose ća lo je 76,2% is pi ta ni ka na še stu di je, bol u gor njem de lu le đa 71,4%, a bol u ra me ni ma 68,3% sto ma to loga. Ovi re zul ta ti se raz li ku ju od na la za is tra ži va nja ura đe nog u Taj va nu, gde je naj ve ća pre va len ci ja bo la bi la u ra me ni ma (75,1%), za tim u vra tu (71,6%) i do njem de lu le đa (66,5%) [4]. 
Is tra ži va nje iz ve de no me đu den tal nim hi gi je ni ča ri ma po kaza lo je da je po treb no oko šest go di na rad nog sta ža da bi do šlo do is po lja va nja simp to ma u gor njim eks tre mi te ti ma. Ovo bi se mo glo ob ja sni ti spo rim uti ca jem mi kro tra u me ko ja iza zi va prome ne i pre ne go što po je di nac ose ti simp to me [7]. 
Po je di na is tra ži va nja po ka zu ju da ve ći na sto ma to lo ga danas ra di u se de ćem po lo ža ju, de sno od pa ci jen ta, gde su usta pa ci jen ta cen tar, a sto ma to log mo že bi ti u po zi ci ji na "8 sa ti" ili "11 sa ti" u od no su na taj cen tar. S er go nom skog sta no vi šta, sto ma to lo zi bi tre ba lo da ra de u po zi ci ji na "12 sa ti" u od no su na pa ci jen ta. Ova kav po lo žaj, po red to ga što se sma tra ne u tralnim, sma nju je po tre bu za po di za njem ru ku i ra me na i do zvolja va do volj no pri bli ža va nje pa ci jen tu, bez me ha nič ke pre pre ke ko ju pred sta vlja se di šte sto ma to lo ške sto li ce [8]. Naj po god ni je su sto ma to lo ške sto li ce s užim na slo nom za le đa pa ci jen ta, ko ji sma nju je po tre bu za ve li kim po di za njem ru ku i ve li kim na ginja njem te ra pe u ta pri ra du [8]. 
Kil pa trik (Kil pa trick) je 1971. go di ne do ka zao da su sto mato lo zi ko ji ima ju po moć asi sten ta i do 16-17% rad no efi ka sni ji i da su kod njih zna čaj no sma nje ni stres i za mor [5]. Pred no sti ra da s asi sten tom su br ža i efi ka sni ja re a li za ci ja in ter ven ci je, kao i oču va nje zdra vlja sto ma to lo ga. Rad uz po moć asi sten ta omo gu ća va sto ma to lo gu da za u zme fi zi o lo ški po volj ni ji po lo žaj te la pri ra du, a isto vre me no se sma nju je po tre ba za okre ta njem te la sto ma to lo ga pri uzi ma nju in stru me na ta i ma te ri ja la sa stoma to lo škog sto či ća. 
Uobi ča je ni po lo žaj sto ma to lo ga pri ra du je eks trem na flek sija gla ve i vra ta sa ra me ni ma po vi je nim na pred. To mo že uzroko va ti skra ći va nje m. ster noc le i do ma sto i de us, m. sca le nus, m. ser ra tus an te ri or i m. pec to ra lis mi nor, dok sred nji i do nji sno po vi m. tra pe si us mo gu bi ti iz du že ni adap ta ci jom na to stanje. Ova kva mi šić na ne rav no te ža mo že igra ti ulo gu u na stanku ne lo ka li zo va nog hro nič nog bo la [9,10]. Dru gi tip mi šić ne ne rav no te že po sto ji u ra me ni ma, iza zvan je pre te ra nim ja čanjem m. del to i de us i m. su pra spi na tus. Ovi mi ši ći su ve o ma raz vi je ni kod sto ma to lo ga zbog če stog po lo ža ja s po dig nu tim ru ka ma, ko je su uda lje ne od te la. Ova kva mi šić na ne rav no te ža mo že uzro ko va ti ne pra vil ne po kre te u ra me nom zglo bu praće ne bo lo vi ma u te ti va ma [11]. Mi šić na ne rav no te ža iz me đu tr bu šnih i mi ši ća do njeg de la le đa, ko ja se če sto ja vlja kod stoma to lo ga, mo že pra vi ti do dat ne te go be. Po na vlja no na gi nja nje ka pa ci jen tu s po vi je nim le đi ma mo že uzro ko va ti pre mor u po vr šnim eks ten zo ri ma do njeg de la le đa, dok du bo ki tr bu šni mi ši ći (m. tran vser sus ab do mi nis i m. ob li qu us ab do mi nis) te že sla blje nju [11]. 
Ame rič ko sto ma to lo ško udru že nje (Ame ri can Den tal As soci a tion -ADA) je ra di spre ča va nja na stan ka mi šić no-ske let nih te go ba kod sto ma to lo ga pre po ru či la če sto is te za nje zglo bo va i pr sti ju, na ro či to pre de la iz me đu pal ca i ka ži pr sta. To kom ra da la kat i/ili po dlak ti ca tre ba da bu du oslo nje ni na sto li cu, či me se obez be đu je sta bi li za ci ja ru ke te ra pe u ta [1]. Glav ni mi ši ći tru pa i ra me nog po ja sa su pred vi đe ni da pru že čvrst i si gu ran oslo nac s ko jeg ru ke mo gu da se po kre ću. Ja ča nje ovih du bo kih mi ši ća je osno va pi la te sa. Pi la tes je pro gram ve žba nja ko ji mo že mno go da do pri ne se mi šić no-ske let nom zdra vlju sto ma to lo ga, a podra zu me va ko ri šće nje la kog op te re će nja i ve li ki broj po na vlja nja. Ve žbe ja ča nja mi ši ća tre ba lo bi iz vo di ti tri pu ta ne delj no s pau zom od jed nog da na iz me đu tre nin ga. Tre ba po če ti s ma lim bro jem tre nin ga i po na vlja nja, pa ih vre me nom po ve ća va ti [2]. 
Ide al ni po lo žaj za rad u or di na ci ji bio bi: vrat u flek si ji od 0 do 10 ste pe ni bez ro ta ci je i na gi nja nja na stra nu, ra me na ko ja su opu šte na sa stra ne, lak to vi u vi si ni usta pa ci jen ta i u flek si ji od oko 90 ste pe ni, a do nji deo le đa pod u prt bla go raz mak nu tim no ga ma, ro ti ra nim spo lja. Sto pa la bi tre ba lo ce lom po vr ši nom da bu du na po du [10]. 
Sa sta no vi šta er go no mi ke, sto li ca za sto ma to lo ga je naj bit ni ja u or di na ci ji [14]. Sto li ca tre ba da odr ža va te lo sto ma to lo ga u ne u tral nom po lo ža ju. Na slon za le đa bi tre ba lo svo jim kon veksi te tom da odr ži pri rod nu lum bal nu lor do zu pri se de nju, pa se zbog to ga na zi va i lum bal ni pod u pi rač. Ovaj lum bal ni podu pi rač tre ba lo bi da bu de vi si ne oko 20 cm, de blji ne 3-5 mm, kon vek san od vr ha do dna, da bi na taj na čin opo na šao pri rod nu lor do zu le đa sto ma to lo ga. Uko li ko bi bio de blji, mo gao bi da pro iz ve de po ve ćan pri ti sak na lum bal ne pr šlje no ve. Ka da su u pi ta nju ve li ki na slo ni za le đa, gor nji kraj ovih na slo na ne sme da uzro ku je pri ti sak na grud ni deo kič me i da ga na taj na čin po ti sku je na pred. Svi na slo ni ko ji pre la ze do nju ivi cu lo pa ti ce mo gu uma nji ti ko ri sti od lum bal nog pod u pi ra ča ta ko što preno se pri ti sak na lo pa ti ce, a tre ba lo bi da bu du oko 6 cm is pod do nje ivi ce lo pa ti ce. Ši ro ke na slo ne za le đa tre ba iz be ga va ti jer mo gu ome ta ti kret nje kič me i la te ral ne po kre te ru ku i ra me na [14]. Sto li ce za te ra pe u te bez na slo na za le đa se ta ko đe sma traju er go nom skim, jer je pri li kom se de nja u ova kvim sto li ca ma kar li ca u pri bli žno ne u tral nom po lo ža ju, kao u se dlu ili pri li kom sta ja nja. Ova kav po lo žaj kar li ce po ma že kič mi da ba lan si ra pri raz li či tim po kre ti ma, ali ova kav di zajn sto li ce ipak po ve ća va pri ti sak na pe ri to ne al nu re gi ju [14]. Mno ga is tra ži va nja po tvrđu ju da na slo ni za ru ke po ma žu u spre ča va nju na stan ka bo la u vra tu, ra me ni ma i do njem de lu le đa, jer sma nju ju ak tiv nost mi ši ća, po seb no gor njih sno po va tra pe zi ju sa do mi nant ne ru ke. Na slo ni za ru ke bi tre ba lo da bu du vi so ko po de si vi i da pru že po dr šku sto ma to lo gu u ne u tral nom po lo ža ju. Do bro po de še ni na slo ni za ru ke spre či će raz voj bo la u vra tu i ra me ni ma. Naslo ni za lak to ve sma nju ju ak tiv nost rom bo i de u sa, i grud nog i cer vi kal nog de la m. er rec tor spi nae [14,15]. Zbog pri ro de po sla, sto ma to lo zi ne mo gu uvek odr ža ti od go va ra ju ći kon takt s lum bal nim pod u pi ra čem sto li ce i mo ra ju se na gi nja ti la ga no na pred, da bi na taj na čin omo gu ći li pre gled od re đe nih po vrši na zu ba. Pri ti sak na di sku se iz me đu pr šlje no va je naj ja či u ovom po lo ža ju, te je ve o ma va žno da sto ma to log na u či ka ko da na od go va ra ju ći na čin sta bi li zu je i za šti ti do nji deo le đa svo jim mi ši ći ma -pr ven stve no tran sver zal nim tr bu šnim mi ši ći ma. Ka da se pra vil no ko ri ste, ovi mi ši ći svo jim dej stvom sma nju ju bol u do njem de lu le đa [14]. 
Osim po lo ža ja, još je dan fak tor ri zi ka je du ži na in ter ven ci je. Do ka za no je da i ni zak ste pen op te re će nja ko ji du go tra je mo že iza zva ti za mor mi ši ća i hro nič ni bol [2]. Ne ke stu di je pred la žu pa u ze od de set mi nu ta to kom in ter ven ci je [4]. Ve ći broj kra ćih pa u za to kom rad nih sa ti (ne du žih od pet se kun di) su mno go prak tič ni je i pru ža ju pot pun opo ra vak za mo re nim mi ši ći ma. To kom ovih mi kro pa u za na pe ti mi ši ći do bi ja ju vi še kr vi i vreme na da se opo ra ve [10]. S ob zi rom na to da se sta tič ni po lo ža ji mo ra ju iz be ga va ti, bi lo bi do bro s vre me na na vre me pri la go đava ti na slon i se di šte, ka ko bi se op te re će nje pre no si lo s tki va na tki vo i na taj na čin mi ni ma li zo va la mi kro tra u ma [5]. 
Kli nič ka sto ma to lo gi ja pod ra zu me va ru ko va nje ma lim vi brira ju ćim in stru men ti ma i po na vlja nje rad nji [1,10]. Do ka za no je da to kom ra da sto ma to lo ga po sto ji ja sna raz li ka u na po ru le ve i de sne ru ke, od no sno do mi nant ne i ne do mi nant ne ru ke. Rad do mi nant nom ru kom zah te va kraj nje fi nu mo tor nu ko or di naci ju, jer ovom ru kom ra di mo ka ko s ruč nim, ta ko i s ma šin skim in stru men ti ma. Po red to ga, po ne kad ovom ru kom dr ži mo puster, si salj ku i ogle dal ce. Ne do mi nant na ru ka se ma hom ko ri sti za asi sten ci ju: da bi se do bi lo pre gled no rad no po lje, da bi se kon tro li sa li po kre ti je zi ka i ekar ti rao obraz, isi sa va la vo da iz usne du plje i sl. Ovo zah te va sta ti čan i po ne kad ve o ma sna žan sti sak ru ke, ta ko da su obe ru ke iz lo že ne sta tič kom op te re će nju, ali s dru ga či jim ulo ga ma [16]. Pri oda bi ru ruč nih instrumenata tre ba lo bi uze ti one koji imaju dr ške ve ćeg preč ni ka, jer se na taj na čin pri ti sak pre no si na ve ću gru pu mi ši ća [16]. 

ZAKLJUČAK

Pre va len ci ja mi šić no-ske let nih te go ba kod no vo sad skih sto mato lo ga je 69,7%. Ove te go be su iz ra že ni je kod mu ška ra ca ne go kod že na. Naj ve ći broj is pi ta ni ka ima te go be u vra tu, ra me ni ma i gor njem de lu le đa. S ob zi rom na ova kav na laz, po treb no je vr ši ti bo lju edu ka ci ju sto ma to lo ga i stu de na ta sto ma to lo gi je o uzro ci ma na stan ka i na či ni ma pre ven ci je po ja ve оvih te go ba. 

NAPOMENA

Re zul ta ti pri ka za ni u ovom ra du su deo is tra ži va nja re a li zova nog u okvi ru pro jek ta pod na zi vom "Is tra ži va nje i raz voj me to da mo de li ra nja i po stu pa ka iz ra de den tal nih na dok na da pri me nom sa vre me nih teh no lo gi ja i ra ču na rom po dr ža nih siste ma" (TR035020), ko ji je fi nan si ra lo Mi ni star stvo pro sve te, na u ke i teh no lo škog raz vo ja Re pu bli ke Sr bi je. 

ZAHVALNICA

Za hva lju je mo Lji lja ni Kne že vić na po mo ći pri sta ti stič koj ob ra di po da ta ka i svim sto ma to lo zi ma ko ji su pri sta li da uče stvu ju u is tra ži va nju. 

Table 1 .

 1 Pain in different body parts in male and female dentists Tabela 1. Učestalost bola u različitim delovima tela u odnosu na pol stomatologa 


		Male	Female
	Body parts	Muškarci	Žene
	Delovi tela	No pain	Pain	No pain	Pain
		Bez bola	Sa bolom	Bez bola	Sa bolom
	Neck Vrat	12 (16.7%) 20 (83.3%) 29 (28.2%) 28 (71.8%)
	Shoulders Ramena	15 (29.2%) 17 (70.8%) 31 (33.3%) 26 (66.7%)
	Elbows Laktovi	26 (75.0%) 6 (25.0%) 54 (92.3%) 3 (7.7%)
	Wrists/hands Ručni zglobovi/šake	20 (49.5%) 12 (50.5%) 38 (51.3%) 19 (48.7%)
	Hips Kukovi	24 (66.7%) 8 (33.3%) 46 (71.8%) 11 (28.2%)
	Upper back Gornji deo leđa	14 (25.0%) 18 (75.0%) 30 (30.8%) 27 (69.2%)
	Lower back Donji deo leđa	15 (29.2%) 17 (70.8%) 33 (38.5%) 24 (61.5%)
	Knees Kolena	25 (70.			

8%) 7 (29.2%) 47 (74.4%) 10 (25.6%) Ankles/feet Gležnjevi/stopala 29 (87.5%) 3 (12.5%) 49 (79.5%) 8 (20.5%) 
ACKNOWLEDGEMENTS

We thank Ljiljana Knežević for help in data analysis, and all dentists who participated in the study.
Prevalence and risk factors for musculoskeletal disorders in dentists