The dentist s operating posture ergonomic aspects

Transcription

1 , pp The dentist s operting posture ergonomic spects Pîrvu C*, Pătrşcu I**, Pîrvu D**, Ionescu C** *Deprtment of Oro-Dentl Dignosis, Ergonomics nd Reserch Methodology, Crol Dvil University of Medicine nd Phrmcy, Buchrest **Deprtment of Dentures Technology nd Dentl Mterils, Crol Dvil University of Medicine nd Phrmcy, Buchrest Correspondence to: Cristin Pîrvu, tutor of Deprtment of Oro-Dentl Dignosis, Ergonomics nd Reserch Methodology, Crol Dvil University of Medicine nd Phrmcy, Buchrest 42 Nitu Vsile Street, Bl. 2, St. 1, 3 rd floor, Ap.15, District 4, Buchrest Moile phone: , E-mil: crstnprv@yhoo.com Received: July 18th, 2013 Accepted: Novemer 18th, 2013 Astrct The prctice of dentistry involves lorious high finesse dentl preprtions, precision nd control in executions tht require prticulr ttention, concentrtion nd ptience of dentist nd finlly dentist s physicl nd mentl resistnce. The optiml rpeutic pproch nd success of prctice involve specil working conditions for dentist nd his tem in n ergonomic environment. The mening of posture in ergonomics is mnner in which different prts of ody re locted nd thus reports re estlished etween m in order to llow specil tsk execution. This rticle discusses posture dopted y dentists when y work, eginning with lnced posture nd going to different vrints of posture. The idel posture of dentist gives him, on one hnd optiml working conditions (ccess, visiility nd control in mouth) nd on or hnd, physicl nd psychologicl comfort throughout execution of clinicl cts. Although me of dentist posture is treted with gret cre nd often presented in undergrdute courses nd continuing eduction courses on ergonomics in dentistry, mny dentists do not know suject well enough nor oreticl issues nd refore nor prcticl pplicility. The risk nd perspective of musculoskeletl disorders relted to unlnced postures should determine dentists tke posturl corrective ctions nd compenstion mesures in order to limit negtive effects of working in d posture. Introduction Keywords: lnced posture, unlnced posture, working positions The prctice of dentistry involves lorious high finesse dentl preprtions, precision nd control in executions tht require prticulr ttention, concentrtion nd ptience of dentist nd finlly dentist s physicl nd mentl resistnce. The optiml rpeutic pproch nd success of prctice involve specil working conditions for dentist nd his tem in n ergonomic environment. The ergonomics pplied in dentistry focuses on prctitioner nd his tem s most importnt resource of prctice. In field of ergonomics pplied in dentistry one of most discussed me is working posture of dentist. The specil ttention on this topic is explined y widely recognized nd ccepted fct tht posture is key of preventing musculoskeletl disorders. The mening of posture in ergonomics is mnner in which different prts of ody re locted nd thus reports estlished etween m in order to llow specil tsk execution. In dentistry, working position represented y sptil rrngement of dentist s entire ody round ptient must e distinguished. This differentition is useful to understnd working conditions. The idel posture of dentist gives him on one hnd, optiml working conditions (ccess, visiility nd control in mouth) nd on or hnd, physicl nd psychologicl comfort throughout execution of clinicl cts. A good" posture provides dentist more working energy, reduced stress level, incresed comfort, lck of pin nd musculr tension nd lower risk for rpeuticl errors. A d posture induces premture ftigue, pin, stress nd negtive ttitude to work, high-risk for musculoskeletl disorders nd poor qulity of work [1]. This rticle discusses posture dopted y dentists when y work, eginning with lnced posture nd going to different vrints of posture. The lnced posture is posture tht should e reference point for postures tht re dily dopted y dentists. Literture provides numerous dt on this topic, mny uthors eing concerned out it. The instnces in which dentists severely devite from n ergonomic working

2 style (which implies correct posture) re extremely numerous from mny resons. The working posture of dentist is strongly influenced y reltionship etween his ody nd different elements of his worksttion, so tht n incorrectly designed worksttion nd/or incorrectly used worksttion ffect posture. By worksttion, we understnd ll sptil nd environmentl elements with which dentist intercts while working [2]. Among sptil elements of dentist s worksttion following cn e identified: dentist s stool, ptient lying in ntomicl chir, components of dentl unit ( dentist s crt, lmp, vcuum system nd control pedl), fixed elements surrounding working re ( fixed furniture, moile cse nd ll tools nd equipment plced on it), equipment used nd presence of dentl ssistnt nd working reltionship estlished with her. The multitude of se items reflect extent to which dentist cn e conditioned nd limited t his worksttion, which my led to n incresed physicl nd mentl stress, often mnifested y feeling of frustrtion" experienced during ll working stges. The dentist s posture evolved from orthosttic posture to seted posture especilly on ccount of dopting four hnds working style [1]. Tody, we meet two posture possiilities ( orthosttic posture nd seted posture) used in vrying degrees. In prctice, we often oserve tht mny dentists work in incorrect postures ecuse of ir hitude, working routine nd poorly designed worksttions. All se conditions ct on lck of dentist s informtion in field of ergonomics nd on ignoring fct tht humn ody hs its dptive limits. Beyond se limits, dentists re exposed to risk of professionl illness. The posture descried in ISO Stndrd Ergonomics - Evlutions of sttic operting postures is recommended for dentists nd is clled lnced or neutrl posture. The lnced or neutrl posture is reference point for correct working posture nd it is recommended to e mintined within limits imposed y prctice conditions, throughout ll stges of clinicl cts. This is seted posture - nturl, unforced, stress free nd symmetricl - tht tkes into ccount loco-motor physiology of humn ody. The neutrl posture is result of generl ergonomic studies dpted to needs of dentl prctice. This posture is comfortle (ssuming miniml contrctions nd musculr tensions), stle (stilizing ll ody segments nd joints) nd symmetricl defining element for posturl lnce. The notion of neutrl" derives from fct tht ech joint of ody hs neutrl zone to which movements re reported nd which recurrent exceeding could generte joint nd muscles overstrin [1]. The lnced or neutrl posture is result of complex positioning of different ody segments, ech of m with its neutrl limits for risk- free use [3]. The lnced posture fetures cn e summrized s it follows [4]: - stright ck nd respect for ody symmetry; voiding rounding ck into C shpe; -forwrd inclintion of trunk of mximum of 20 ; greter forwrd inclintion, tilting to side nd trunk rottion re contrindicted; -forwrd inclintion of hed up to from trunk; - rms plced long ody, forwrd oriented within 10 ; forerms rised up to 25 from horizontl line; - ngle etween thighs nd shnks of or more; - thighs prt up to 45, voiding rigid fixtion of hip joint; - shnks oriented perpendiculr to floor or slightly posterior; - feet on floor oriented forwrds in sme plne with shnks; when feet re symmetricllyy positioned elow opertor hnds, posture is lnced. The posturl symmetry implies ll ody horizontl lines ( eyes, shoulders, elows, hips nd knees horizontls) eing prllel nd perpendiculr to medin line of ody [4]. c Fig. 1,,c The lnced posture 178

3 Preserving lnced posture nd its symmetry throughout clinicl ct is lrgely conditioned y reltionship estlished etween dentist nd introrl working field. In n idel sitution, surfce of treted teeth should e prllel to front of dentist nd his view oriented perpendiculr to working field. It is recommended tht distnce etween working field nd dentist s eyes is of cm or slightly higher for very tll dentists. When this reltionship is not estlished or it is lost during clinicl ct, dentist s eyes will look for it nd dentist will deprt instinctively from lnced posture. To estlish such reltionship it is importnt to py ttention to dentist s position round ptient nd ptient s hed position on hedrest. To position ptient s hed it is importnt to use ll his possiilities of motion: extension nd flexion, rottion right or left nd side flexion right or left in vrying degrees nd comintions [5]. The lnced posture does not require rigid ody ttitude. The dentist hs freedom to move within some limits so tht no hrmful positions result. Gentle relncing movements re often mde. The specilty literture uses concept of ctive nd pssive lnced posture. The ctive lnced posture involves dentist supporting ck stright ( physiologicl spine curvtures nd S" spine form) only y mens of prverterl muscles tonicity. The pssive lnced posture is chrcterized y use of lumr support provided y set ck [4]. To mintin n idel posture for s long s possile, working equipment nd working spce ( worksttion) must e tilored to dentist nd it must fit him like glove. This idel sitution corresponds to most fvorle positioning of dentist s hed, ody segments, dominnt hnd nd fingers, elements tht cn e tested y proprioceptive control ccording to proprioceptive derivtion concept. Numerous tests hve een done on dentists who were left to look for lindly nd to feel most convenient working ody position (posture) tht llowed m high working finesse nd good mnul control, sking m to try to ignore ir equipment round nd ir old hits. The results showed numer of preferences: plcing dominnt hnd index round rmpit level on midline of ody nd dentist sitting with ck stright without using support from ckrest [6]. In order to tke nd use medicl tools, dentist extends his rm horizontlly nd verticlly so tht llowing this service without compromising lnced posture, tools must properly positioned [6]. Using mgnifiction systems (glsses nd corrective lenses, loupes nd telescopes, operting microscope) deserves specil ttention ecuse it could hve serious implictions for posture. Properly chosen nd djusted, mgnifiction systems cn prevent ending of dentist s hed nd development of musculoskeletl disorders. On or hnd, ir misuse could hve dverse effects, incresing risk of musculoskeletl injuries or ggrvting m [7]. The prolonged sttic postures re strongly incriminted in etiology of musculoskeletl disorders nd refore y deserve specil ttention. Sitting on chir for long time involves ctivtion of prverterl muscles nd sustntil chrging" of lumr curvture of spine higher thn stnding (2.7). To mintin posture for long time, including lnced posture, predominntly involves sttic musculr effort. The sttic work is more tiring thn dynmic work though it requires lower oxygen consumption. In sttic work to nerve centers of cererl cortex, lrge numer of impulses from proprioceptors of muscles nd tendons rech sme plce, this mening continuous long time excittion of se cererl cortex nerve centers. This mechnism explins why sttic work is more tiring thn dynmic work [8]. On or hnd, in sttic posture (especilly if it is incorrect) oxygen supply to muscles my e ffected, which trnsltes quickly through muscle inefficiency nd even pin. In dynmic work functions, muscle pump ( lterntive contrction nd relxtion of muscles) promotes lood circultion [4,9-11]. Studies hve een mde which showed tht mintining posture requires more thn 50% of ody muscles to e isometriclly contrcted, which mens n intense musculr effort. This effort cn led to musculr overworking, poor lood irrigtion nd n incresed pressure on joints nd muscles [12]. When prolonged sttic posture is dded, or postures constrints its effects. On or hnd, discomfort cused y prolonged sttic posture nd required recovery times re directly proportionl to time spent in this mnner [13]. In order to compenste effects of sttic work nd posturl demnds, mny uthors recommend dynmic wy of working. This includes: - employing ctive lnced posture nd pssive lnced posture lterntively; -using short reks etween ptients in order to leve stool nd wlk; - working progrm with long demnding tretment sessions lternting to short nd esier ones; 179

4 -performing simple exercises etween ptients t end of progrm [1]. Although importnce of lnced posture to void prolonged sttic posture is widely recognized, some uthors recommend use of severl lterntive postures in order to employ more musculr groups [14-16]. A specific study shows tht dentists who work exclusively seted, suffer more pronounced pin in lumr curvture of spine compred with dentists who lternte seted posture with orthosttic posture [17]. There re uthors who recommend chnging posture nd position fter mximum one hour of working. On or hnd, during long clinicl cts, puse of five minutes fter one hour of ctivity would e welcomed in terms of posturl chllenge to oth dentist nd ptient. The position of ptient (especilly hed positions) my lso ecome tiring when clinicl ct is extended [18]. The mentl nd psycho-emotionl stress cused y difficulty of working cn induce n incresed musculr tension, reduced ttention to posture nd finlly wider ody response to d posture [7,10]. Using n ergonomic stool nd djusting it correctly nd in n esy wy hs mjor contriution in doption nd mintennce of lnced posture. Through its fetures, dentist s stool hs to encourge good posture [2]. The stool s height djustment is necessry for correct orienttion of thighs to floor nd minimum ngle of º etween thighs nd shnks. A too high position of stool requires sitting on edge, losing weight distriution on stool xis nd losing contct of dentist s ck with stool s ck. This wy, risk of slipping off stool ppers. When stool is too low, lumr curvture of spine is reduced through posterior rottion of pelvis [7]. The orienttion of dentist s stool se cn e horizontlly or forwrdly inclined. A horizontl stool se my cuse posterior rottion of pelvis nd reduction of lumr curvture of spine while its forwrd inclintion prevents this phenomenon. In ddition, horizontl stool se with too lrge surfce nd hrd edge cn generte posterior compression of thighs, which ffects shnks nd legs lood supply. By tilting stool se, this phenomenon is voided. The tilting degree must e reduced t 5 to 15º ecuse igger degree could determine sliding off chir. A sddleshped stool se does not pose such prolems, eing fvorle from this point of view. Both forwrd inclintion of se nd sddle-shped se conformtion llow trunk-thigh ngle greter thn 90 nd closeness to ptient which fcilittes etter ccess nd visiility in ptient s mouth [1,7]. Supporting ck on ckrest of stool is necessry in order to void musculr ftigue nd reduction of lumr curvture of spine during long clinicl cts. A properly support does not require gret height of ckrest, 20 cm eing sufficient [7].The lumr support is recommended to e set on upper hlf of lower ck, where switching to thorcic convexity [1]. The reltionship etween position nd stool se nd position of ckrest is especilly importnt to reduce lumr curvture tension [2]. Incresing ngle etween torso nd thighs in order to position closer to ptient, hs fvorle effect reducing lumr kyphosis [13]. For long lsting clinicl cts is lso importnt to support rms on specil supports of stool. This support ddresses in sme time to shoulders, preventing ck pin nd shoulder nd neck tension tht my occur due to prolonged musculr tension. The stool with supports for rms is igger nd it seems to limit free movements (especilly if we do not hve proper conditions to pproch ptient). For this reson, it is often voided y prctitioners, ut fter while of use nd dpttion, enefits ecome cler [19]. In order to respect symmetry of lnced posture it is recommended to use supports for oth rms simultneously [5]. The devitions from lnced posture In prctice, it is lmost impossile for dentists to mintin lnced posture throughout long clinicl ct even when this posture is very well known nd initilly dopted. Fully wre of effects of n incorrect posture, dentists should consider devitions s rre s possile, of smll mplitude nd short durtion. The wider nd longer se devitions re, more risk of MSDs increses [3]. The devitions from lnced posture during clinicl ct my e cused y: -n incorrect positioning of dentist round ptient ccording working re; -n indequte working level (often mouth is too low); -n incorrect positioning of ptient's hed (not rotted, tilted or extended enough); -voiding to work in n indirect vision (working in mirror is more difficult nd requires extr effort fixing imge); As mens of devition from lnced position, following cn e seen most often [1,12]: - excessive ending of dentist s hed nd extent of neck, rottion nd tilting of hed; 180

5 - tilting nd rottion of trunk on one side; -lifted rms (dominnt, non-dominnt or oth) without dequte support on trunk or on rm support of stool; -lifting one shoulder or oth; -n incresed thorcic curvture of lumr curvture reduction; - ngle etween thighs nd shnks elow 90. Avoiding ptient set ckrest nd hedrest mrgins, in order to gin ccess nd visiility in mouth, ptient s shoulder or some tools crete conditions for poor unlnced posture. The direct consequences of se interferences" re twisting nd tilting ody segments (hed, shoulders nd trunk) on one side nd rising elows nd shoulders. In sence of specific ttention to posturl chnges, se my ecome repetitive nd of long stnding. On or hnd, due to interferences, need for repetitive repositioning of tools, equipment or ptient, reduce dentist s chnce of working in lnced posture. The ct of repositioning could compromise posture fvoring occurrence of musculoskeletl disorders, reducing ccess to mouth nd creting conditions for working incidents nd poor lighting of surgicl field. All se conditions led to physicl nd mentl ftigue nd tension. Avoiding interferences nd repetitive repositioning cuse ftigue, confusion nd conditions for musculoskeletl disorders [6]. The frequent unidirectionl trunk twisting nd tilting is consequence of fulty positioning of tools, equipment nd mterils. Positioning se useful items t ig distnce outside working re of dentist ( circulr re round dentist descried y forerms length in his sight) forces him to devite from lnced posture. The help of dentl ssistnt regrding tools lso hnding hs mjor influence on posturl devitions of dentist [14]. The unlnced dentist s postures In dentistry prctice, only orthosttic posture cn e often seen despite its mny disdvntges. The dentist s orthosttic posture is n symmetricl posture with ody support minly on right foot nd internl orgn compression on right side due to ending towrds ptient. Only certin short clinicl cts should e done in this posture (e.g.: ite records, impressions, some extrctions, estic evlutions) [9,11]. The possile cuses of mintining this posture re: hitude, chnging resistnce, intensive working rhythm, feeling of losing some freedom of movements once sitting on stool nd working unssisted or ssisted only in prt y dentl ssistnt ( dentist himself tkes tools, which requires moving free in office spce for esy ccess). Fig. 3 The orthosttic unlnced posture Anor dentist s unlnced posture is seting posture with upper ody tilted on right side cused y verticl or only slightly olique positioning of ptients. Compred with orthosttic posture, it protects shnks nd legs ut ll prolems ssocited with of mrked long mintined symmetry re still mnifesting. Twisting trunk in only one direction leds to serious musculr nd joint unlnces nd fvors low ck pin [20]. Fig. 2, The frequent devitions from lnced posture 181

6 Fig. 4 -f The seted unlnced posture c e f d Conclusions Although me of dentist s posture is treted with gret cre nd often presented in undergrdute courses nd continuing eduction courses on ergonomics in dentistry, mny dentists do not know suject well enough, nor oreticlly, nd refore nor its prcticl pplicility. Unfortuntely, mny dentists re in sitution of feeling negtive effects of unlnced postures in first yers of prctice. In cse musculoskeletl disorders rise, y should tke correcting ctions nd compenstory mesures in order to compenste negtive effects of unlnced posture. Ech dentist who feels responsile for his helth should ressess his working posture. A good posture is not luxury nd it does not require mjor investments ut rethinking of wy of working. The dentists should not live ir professionl life in terms of discomfort nd musculoskeletl disorders perspective. References 1. An introduction to ergonomics: risk fctors, MSDs, pproches nd interventions, A report of Ergonomics nd Disility Support Advisory Committee (EDSAC) to Council on Dentl Prctice (CDP), 2004, ADA.org. 2. Todd AI, Bennett AI, Christie CJ. Physicl implictions of prolonged sitting in confined posture A literture review. Ergonomics SA. 2007; 19: Lri HA, Suyetenkov DYе. Musculoskeletl dysfunction in dentl prctice. Russin Open Medicl Journl. 2012; 1: Hokwerd O. Symposim: Ergonomic principles for pcient tretment, Syllus pper, 2004, Timişor. 5. Hokwerd O, Wouter JAJ, Ruijeter RAG, Zijlstr-Shw S. Ergonomic requirements for dentl equipement. ESDE Dougherty M. Ergonomic principles in dentl setting: Prt 1, dentlproducts.net., Vlchi B. Ergonomics nd Injury in Dentl Office, A peer-reviewed, 8. Niculescu T, Tode A, Tom I, Pvel A, Niculescu R. Medicin Muncii, 2003, Bucureşti, Editur MEDMUD. 9. Anghel M. Noţiuni generle de ergonomie dentră, 2005, Timişor, Editur Orizonturi Universitre. 10. Porter JA. Ergonomics nd Physicl Well-Being, Prt 1: Identifying Prolem, Anghel M, Argesnu V, Tlpos- Niculescu C, Lungenu D. Musculoskeletl disorders (MSDs) Consequence of prolonged sttic posture. Journl of Experimentl Medicl & Surgicl Reserch. 2007; 4: Vlchi B, Vlchi K. Mechnism leding to musculoskeletl disorders in dentistry. JADA. 2003; 134: Corlett EN. Bckground to sitting t work: reserch requirements for design of work sets. Ergonomics. 2006; 49: Gosvi SS, Gosvi SY, Jwde RS. Posturedontics: Reducing Stress in Dentistry. World J. Dent. 2012; 3: Finsen L, Christensen H, Bkke M. Musculoskeletl disorders mong dentists nd vrition in dentl work. Appl Ergon. 1997;29: Cllghn J, McGill S. Low ck joint loding nd kinemtics during stnding nd unsupported sitting. Ergonomics. 2001;44: Rtzon N, Yros M, Mizlik A, Knner T. Musculoskeletl symptoms mong dentists in reltion to work posture. Work. 2000;15: Murphy DC. Ergonomics nd The Dentl Cre Worker, Americn Pulic Helth Associtions, Prsell DE, Weer MD, Anderson BC, Co GW Jr. Evlution of ergonomic dentl stools through clinicl simultion. Gen Dent. 2000;48: Toren A. Muscle ctivity nd rnge of motion during ctive trunk rottion in sitting posture. Appl Ergon. 2001;32: