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Principles of Efficient Dental Equipment Use
ORIGINAL ARTICLES The dentist's efficiency in treating his patients is partly determined by the efficiency of his operating environment, particularly his instruments and equipment. This paper presents 26 principles for the design of effective and time-saving dental equipment that meets the operating needs of the dentist. Each piece of equipment is coordinated with all other equipment in the office to form a complete functional operating unit.
Principles of efficient dental equipment use Elbert O. Thompson, DDS, Salt Lake City
Ideal operating objectives of the prudent and conscientious dentist require that his training, his skills, and his operating environment serve his patients efficiently. The dentist’s training and skills are paramount in importance, but these qualifications are enhanced or diminished by his operating environment that includes his tools and equipment. A personal equation in this environ ment is vital to his efficient performance, but some basic principles can be applied to all types of dental practice.
General considerations * D en tist’s operatin g needs: Engineering, manu facturing, advertising, and merchandising specifi cations have influenced dental equipment design. The resulting production of dental equipment does not always meet the operating needs of the den tist. This paper attempts to relate the dentist’s operating needs to the equipment that is created to serve these needs. 708
■ N e e d fo r concept-thinking: If a piece of den tal equipment is to be effective, it must be coor dinated with all other equipment in the office. It would not be logical to design a dental unit inde pendent of the dental chair, the dental operating stool, or the dental cabinet. A ll pieces of equip ment must be part of a single concept since their design and function are interdependent.
■ H appin ess an d efficiency: Because efficiency in function is the ultimate objective in the design of equipment, it is important that facets that promote an environment of happiness, peace, and efficiency for the patient and dental operating team are in corporated in design principles. A progressive appraisal of principles must not be influenced by a reckless desire to change or by marketing or manufacturing patterns that are linked to the past unless these patterns are ob jectively based on principles that will always pro mote effective dentistry. Proper placement of equipment components for
proficient use saves tim e an d effort and offers m ini m al interference w ith operating m otion patterns. Simplicity of design contributes to rapid, easy cleaning and disinfection. A utom ation, w herever possible, m inim al weights, torques, and bends in the use of an instrum ent reduce stress. A preplanned design w ith proper placem ent of equipm ent, supplies, and instrum ents reduces tension and adds to the happiness and efficiency of the operating environm ent.
D efinition of terms ■ O perating ovoid: T he operating ovoid is the region w here all instrum ents and equipm ent used in treatm ent are located. D u rin g treatm ent, the patient’s head is located in the center of this region w here all instrum ents and equipm ent can be efficiently reached by the operating dentist and his assistant. D uring treatm ent, the patient’s head is located in the center of this region.
Fig. 1 ■ Euthenics dentistry m obile unit m anifold a t tach ed to dental chair. Dynam ic instrum ents are housed in m anifold and go up and down w ith ch a ir and slide b ack and forth to m eet operating variab les
■ O perating variables: Properly designed dental equipm ent m ust efficiently serve the following operating variables: 1. E ach patient, no m atter w hat his physical build o r height, m ust be served com fortably in varying positions. 2. T he dentist should be able to w ork efficient ly alone o r with one or m ore chairside assistants. 3. T he dentist and assistant should be able to w ork efficiently in a standing o r sitting posi tion. ■ Sta n d -u p den tistry: This term applies to the concept of having the dentist stand behind the patient, w orking with slow-speed rotary and hand cutting instrum ents, and using indirect vision by m eans of the m outh m irror. ■ S it-d o w n d entistry: This term applies to the concept of having th e patien t recline in a con toured dental chair and having the dentist and assistant sit com fortably on operating stools close to the patient’s head so th at they can w ork with direct or indirect vision. T h e dentist should be able to operate not only from a sitting but also from standing position w ithout equipm ent design dictating posture com prom ise. ■ E u th en ics: This term is derived from the G reek, euthenia, w hich m eans well-being, and from the term , euthenein, w hich m eans to thrive.
Fig. 2 ■ M o b ile operating cab inet serves dentist or assistant in seated or standing positions. It contains static instrum ents, im m ediately needed supplies. X - ra y view box, am algam ato r, tim er, and so forth. Top w o rk ing surface serves as operating tra y and positions tim e and motion drug tray. A s m any as 1,200 items can be e fficie n tly organized for im m ediate use in cab in et by either member of operating team
Thompson: EFFIC IENT DENTAL EQ UIPM EN T USE ■ 709
W ebster’s New Collegiate D ictionary1 (1 9 6 1 ) defines “euthenics” as “The science having to do with the betterm ent of living conditions to secure m ore efficient hum an beings.” ■ C om ponent instrum ents: T hese are instru m ents used by the dentist-assistant team . They are assigned to one of the three groups as follow: 1. D ynam ic instrum ents (Fig. 1) include those instrum ents with cord, hose, or tube attachm ents. 2. Static instrum ents (Fig. 2 ) include all hand instrum ents. 3. Im m ediate operating supplies (Fig. 2 ) in clude m inim al supplies and articles needed for operation. ■ M anifold concept: (Fig. 1, 3) T he m anifold concept is a new idea in dental unit design th at m akes dynam ic instrum ents accessible from the front-left of the patient so that these instrum ents
are related to the patient’s head throughout all operating variables. No instrum ents, trays, or brackets are positioned over the patient. ■ Evacuative system : This system is an effec tive m ethod of evacuating liquids and solid debris from the patient’s m outh by m eans of a powerful but gentle negative airstream . This system filters the liquids from the solids and separates them from the negative airstream . A clean, clear, washed operating field is m ade possible. This evacuative system and its use are term ed “washed-field den tistry.”2 ■ Saliva cross-contam ination: This term refers to the spread of bacteria in the patient’s saliva by the o p e rato r’s hands and instrum ents. ■ Cuspidor calisthenics: M ovem ent of the p a tient to and from the dental cuspidor.
Fig. 3 ■ Euthenics dentistry concept places p a tien t's head in cen ter of operating ovoid. D yn am ic instrum ents at front left of patient in m obile dental unit m anifold are a v a ila b le to both members of operating team . S tatic instrum ents and im m ediately needed supplies are provided in mobile operating cab inet behind patient. P a tie n t and operating team sit com fo rtab ly with m inim al stress. No instruments, trays, and so forth are over top of p atien t to interfere with operating motion patterns or to endanger safety o f patient 710
■ JAD A, Vol. 74, March 1967
Principles ■ D e n ta l e q u ip m e n t m u s t fu n c tio n efficiently to m e e t im m e d ia te e q u ip m e n t n eeds th ro u g h all o p er a ting variables: T he dentist’s efficiency is chal
lenged if there is w asted m otion in reaching com ponent instrum ents from the operating stool or from a standing operating position. T herefore, it is im portant th a t dental equipm ent provide all com ponent instrum ents for ready use throughout all operating variables. ■ A ll c o m p o n e n t in stru m e n ts m u st be im m ed ia tely available to b o th d en tist a nd chairside assistant d u rin g all operative variables: Two designs in dental equipm ent have attem pted to m eet this re quirem ent: 1. Designs th at require the patient to be m oved to the com ponent instrum ents are built around the fixed dental unit th a t houses and serv ices varying num bers of com ponent instrum ents. This equipm ent em bodies the basic design that has served stand-up dentistry in the past. Bracket tables with service trays for some static instru m ents have been planned for use over the patient seated in the dental chair. W hen sit-dow n dentistry was introduced, the seated dentist could not conveniently reach his instrum ents on the fixed dental unit. Therefore, the dental chair track concept was designed to allow th e dentist to m ove the patient forw ard. T he distance betw een these instrum ents and the patient’s head was shortened. This d ental chair track concept had m any disadvantages: when the patient was seated in the dental chair and the den tal ch air was m oved on the dental ch air track, the operating light, the foot control, the dentist’s operating stool, the assistant’s operating stool, and the bracket table o r operating cabinet had to be relocated. A lso, the related dental cabinets th at contained static instrum ents o r needed im m ediate supplies had to be moved. E ach m ove m ent had to be m ade m anually. A com plex pat tern of cross-contam ination developed. T here fore, operating cleanliness required disinfecting and hand-w ashing procedures each tim e the pa tient was moved. T he dental chair track produces interference in relating the foot control and the operating stools to the patient. C asters cannot easily move over the m etal tracks behind the forw ard-posi tioned dental chair. 2. T he equipm ent th at is designed to bring the com ponent instrum ents to the patient allows the
patient to be positioned in any operating variable, and the dynam ic instrum ents are brought to the patient through the m anifold concept design (Fig. 1, 3 ). Similarly, static instrum ents and im m edi ately needed supplies, all contained in the mobile operating cabinet (Fig. 2 ) can be positioned directly behind the patient so as to be convenient to each m em ber of the operating team. ■ D e n ta l e q u ip m e n t sh o u ld b e d esig n ed to bring a ll co m p o n e n t in stru m en ts, sta tic in stru m en ts, a n d im m ed ia te o p era tin g su p p lies to w a rd or aw ay fr o m th e p a tien t, w h o se o p era tin g p o stu re re m a in s a lm o st co n sta n t in th e ce n te r o f th e o p era t in g o v o id (Fig. 3 ). ■ A co m p le te c o m p le m e n t o f c o m p o n e n t in stru m e n ts sh o u ld b e in clu d ed in th e o p era tin g o vo id e q u ip m e n t to se rve th e n eed s o f th e operating d en tist: Past developm ents in dental equipm ent have resulted in a confused hodgepodge of con trols, cords, and tubes. A n efficient operating procedure would not require any m em ber of the operating team to procure, plug in, or attach a com ponent instrum ent before use o r unplug o r detach and return a com ponent instrum ent to storage position after use. M axim um use of dental equipm ent can be ex pected only through the kind of sm oothly func tioning design th a t perm its use w ithout interrupt ing the operation (Fig. 1 ). A n efficient design would provide esthetic housing, constant attach m ent for easy use, and autom ation for all com ponent instrum ents that are used reasonably often. ■ E q u ip m e n t in th e tre a tm en t region sh o u ld be in o ffen sive in a p p earance a n d as esth etic as p o s sible. I t sh o u ld contain, rather th a n m ere ly su p port, as m a n y o f th e c o m p o n e n t d y n a m ic in stru m e n ts as po ssib le: Unsightly cords, hoses, tubes, m otors, trays, and bracket arm s need not becom e a “m onster” th at upsets the patient psy chologically. Efficient housing and organization of effectively placed instrum ents add to the eu thenics concept and minimize the visual stress (Fig. 4 ) . ■ D y n a m ic in stru m en ts sh o u ld be accessible to th e p a tie n t’s m o u th fro m th e 5 o ’clo ck to th e 6 o ’clo ck p o sitio n zo n e: W ork simplification studies have established an operating zone for the dentist th at allows his hands and arm s freedom of m ovem ent between the 6 o ’clock and 11 o ’clock po Thompson: EFFICIENT DENTAL EQ UIPM ENT USE ■ 711
dental chair is raised or lowered and slide back and forth in a horizontal position to accom m odate operating variables (Fig. 1 ): The m anifold ar rangem ent, easily repositioned, provides that dy nam ic instrum ents can be constantly related to the patient’s m outh through even extrem e operat ing variables and can be available to both dentist and assistant w hether they are seated or standing. ■ E quipm ent design should, wherever practical, provide autom atic activation and deactivation of dynam ic instrum ents to elim inate m anual switch manipulation: This autom ation principle, in com bination with the modified manual-switching or foot-switching design, saves motions involved in reaching for switches while the dentist’s at tention is focused on his work. It also minimizes saliva cross-contam ination with required disinfec tion procedures. Fig. 4 ■ Euthenics dentistry drawer under ch a ir e ffe c tive ly uses space under foot of dental chair. Electric surgical instruments, photographic equipm ent, and so forth can be housed in drawer. Electric power can be a u to m a tic a lly turned on as drawer opens and turned off as draw er closes
sitions. The dental assistant has freedom of hand and arm m ovem ent from the 1 o’clock to the 5 o ’clock positions. T hus, the area betw een the 5 o ’clock and 6 o ’clock positions is free for the approach of dynam ic instrum ents w ithout interfer ing with the m otion patterns of the dentist or those of his assistant. ■ Cords, hoses, and tubes attached to dynam ic in strum ents should be as short, as light in weight, as torque-free, and as bend-free as operating lim its will allow during use: E xperim ents have show n th at the m anifold concept (Fig. 1) p ro vides an efficient rem edy for the aforem entioned principles. ■ Instrum ents, dynam ic or static, should not be placed over the patient while he is in the dental chair: Patient welfare is the objective of all conscientious dentists. Instrum ents and m aterials should not be positioned over the patien t’s body and during use should be guided around, not over, the patien t’s head to minimize accident hazards. Efficient arrangem ent of dynam ic instrum ents can be m ade to function effectively in the m anifold concept (Fig. 3 ). ■ D ynam ic instrum ents should be so related to the dental chair that they go up and down as the 712 ■ JA D A , Vol. 74, March 1967
■ The turbine variable foot control should be ori ented. and stabilized for im m ediate availability. The operator or chairside assistant should not need to search for or m anually position this foot control for use in any operating variable position: D uring the dental operation, the dentist must change his operating position frequently and often rapidly to com plete an operation efficiently. C on ventional foot controls have had to be manually m oved as operating positions change. The euthen ics dentistry concept provides that the foot control can be recessed and fixed to the base of the mobile operating cabinet (Fig. 2 ) so that it is stabilized in constant relation to the cabinet and can be easily seen by the operator and efficiently used. This arrangem ent has the additional advan tage of elim inating unsightly, unclean, and unsafe foot control cords from the treatm ent region. ■ Floor channels or crawl space underneath the floor should be provided for m odern dental equip m ent installation in office planning: Expense of installation in drilling floors and providing service, tubing, wire, pipe, and so forth can be reduced to a m inim um with intelligent advance planning and is insignificant com pared to advantages gained in efficient operation. New equipm ent that might be designed in the future should also be anticipated in the plans. ■ Static instrum ents and im m ediately needed sup plies should be contained in the m obile dental operating cabinet that should be located behind
«r
m otion and vision. The seated posture of dentist and assistant changes since operating needs neces sitate varying positions and postures. A n efficient stool will com plem ent and not hinder these oper ating posture requirem ents.
Fig. 5 ■ Euthenics dentistry operating stools support dentist and assistant with foot support and torso support with ve rtical height adjustm ent of seat possible w ithout m anual controls
the patient for m ost efficient operation (Fig. 2 ) : Because the chairside assistant frequently pro cures and returns static instrum ents during an operation, her right hand is positioned to reach for and replace instrum ents w hen the operating tray is placed on top of the mobile operating cabinet behind the patient. M obility of the mobile operating cabinet is im portant to ensure proper use of all static instrum ents and supplies. T he operating cabinet should be designed with spe cially constructed “tim e and m otion” inserts to contain, ready for im m ediate use, as m any as 1,200 items necessary in the average dental practice. * Operating stools for dentist and assistant should provide for instantaneous variations in height w ithout m anual adjustm ent and should provide body support for cantilevered operating postures and an elevated fo o t rest (Fig. 5 ) : The ideal operating stool should support its own weight on a base designed for sm ooth, gliding movem ents w ithout tipping hazards and should be designed to provide instantaneous changes in vertical seat ing levels w ithout m anual adjustm ent. T he assist ant should sit higher than the dentist to assist effectively w ithout interfering w ith his operating
■ O nly equipm ent necessary for efficient, organ ized operating procedures should be placed in the treatm ent region. This treatm ent region should not be used for storage of item s that are not used reg ularly: T he euthenics dentistry wall secretary (Fig. 6 ) organizes patient’s records for preplan ning operating procedures by presenting patient’s records and radiographs for study before the p a tient is seated. A ny im portant negative history can readily be considered for m ore efficient dental service. All records for the day’s operation can be organized, posted, and controlled through p roper use of dental equipm ent. C om ponent instrum ents seldom used and sup plies in excess of actual operating needs should be organized and stored conveniently close to, b u t outside, the operating region. ■ D ental equipm ent should be designed to func tion as quietly as possible. Necessary noise should be camouflaged: Noise can be controlled by proper location of m otors, telephones, and so forth. T reatm ent regions should be sound-treated with acoustical tile in ceiling, drapes on windows and, when desired, carpet on the floor. Softsoled shoes should be worn by operating team m em bers, and conversation should be as quiet as possible. Background music, w hen restful, is recom m ended. M usic can be especially effective when com bined with dental education and psychological conditioning program s w hen directed to the p a tient by m eans of lightweight, com fortable-fitting, and high-fidelity stethoscope earphones (Fig. 7 ). These program s can be controlled by m eans of the epic center, which can be located in the face of the euthenics dentistry m obile unit m anifold (Fig. 1, 7 ). ■ Unpleasant odors should not be noticeable in the dental office: Properly designed and effi ciently used evacuative systems can do m uch to protect the patient and the operating team from offensive m outh odors that occur during the oper ation. O dorous drugs should be kept in sealed containers. A thorough disinfection and cleaning program is also vital to the p roper control of Thompson: EFFIC IENT DENTAL EQ UIPM EN T USE ■ 713
Fig. 6 ■ W a l l secretary can be m ounted on right treatm en t w all. W a ll secretary provides space for patien t records, X - ra y view box, pull-down w ritin g desk, models for patient ed u ca tion and case presentation, telephone, an d intercoms
odors. W aste receptacles outside the treatm ent region can be effectively planned to reduce further unpleasant odors. ■ D en ta l e q u ip m e n t sh o u ld be d esig n ed so all ex te rn a l a n d internal p a rts are readily accessible fo r installation a n d service (F ig. 8 ) : Access panels th at can be easily rem oved to expose in ternal equipm ent parts that need to be reached for installation and service are vital to efficient equipm ent planning. ■ D en ta l e q u ip m e n t sh o u ld be d esig n ed to fit in th e sm a ll o p era to ry as w ell as in the large operatory. T he euthenics dentistry concept creates a self-contained operating island th at effectively ful fills this principle. 714 ■ JA D A , Vol. 74, March 1967
■ C o n tro ls s h o u ld b e p ro v id e d in d en ta l u n it d e sign th a t en a b le th e d en tist to a d ju st air p ressu re a n d vo lu m e , w a ter p ressu re a n d vo lu m e , a n d oil d rip ra tes to d esired standards: It is vital to the proper function of these instrum ents, as they re late to the m anufacturer’s instructions, th at they can be easily adjusted to the operator’s desires for m axim um perform ance. ■ E q u ip m e n t design sh o u ld p ro v id e e v ery n ee d ed fa cility to e m p ty the p a tie n t’s m o u th co m fo r ta b ly a n d efficiently: By the washed-field dentistry principles th at use the 10-mm. m outhpiece and hydroceptor, liquids and solids can be instantane ously evacuated from the patient’s m outh to en able the dental operation to proceed efficiently.
drain autom atically into the sewer line, and the solids should accum ulate so they can be disposed of o r so their precious m etal value can be re claim ed. T he separating system should be easily disassem bled for cleaning and disinfecting so bac terial grow th with accom panying odors can be controlled. ■ T h e d en ta l chair b a ck sh o u ld be as th in as p o s sible: A dental chair with a thin back allows the p atient’s head to be placed in the dentist’s lap fo r m axim um operating efficiency w hen the dentist is in a seated position (Fig. 9 ). T he euthenics dentistry neckrest should sup po rt the p atient’s head in its norm al relation to the torso, regardless of operating position or size of patient (Fig. 1 0 ). This position helps to reduce problem s related to gagging and swallowing re flexes. Fig. 7 ■ Epic center in face m obile unit m anifold controls which play-b ack instrum ents can m aterial or en tertain m en t during histories, patien t instruction, or also be recorded through control
of euthenics dentistry five chan nels through relay p atient education dental treatm ent. Case case presentation can system
If a conventional cuspidor is advantageous, in addition to the evacuative system, it should not occupy critical space th at is needed by the assistant, and it should be out of sight w hen n o t in use and autom ated w ith w ater flow w hen brought into function. E uthenics dentistry provides (Fig. 1, 3) an autom ated evacuative m outhpiece th at can be used by the dentist, by the assistant, or by the patient him self to rem ove liquids o r solids from the patient’s m outh. If this m ethod is used, a con ventional cuspidor o r a funnel into which the p a tient could em pty his m outh w ould not be needed. C uspidor calisthenics that interfere with efficient operating program s can therefore be elim inated.
■ D e n ta l chair base design n eed n o t allow fo r co u n tersin kin g in to th e floor: T he dental chair,
Fig. 8 ■ Euthenics dentistry fixed unit foun tain head houses all services to d ynam ic instruments, volum e con trols, pressure controls, filters, oilers, and tubes, which are read ily a v a ila b le for service since top and sides open com pletely
■ E va c u a tiv e e q u ip m e n t sh o u ld be d esig n ed w ith an a u to m a tic separating a n d filtering sy ste m th a t can be d isa ssem b le d fo r fre q u e n t cleaning a n d that can fu n c tio n as p a rt o f th e d en ta l unit: Solids and liquids m ust not be draw n into m ain air lines since these air lines becom e bacterially contam i nated. Sludge and bacterial contam inated masses build up to becom e deterrents to efficient airflow. Solids and liquids are preferably separated from the functioning negative airstream in a separating system located in the dental unit. L iquids should Thompson: EFFIC IEN T DENTAL EQ UIPM ENT USE ■ 715
w ith the patient in a supine operating position, will need to be raised to m ake room for the o p er ating team ’s knees (Fig. 9 ) . T here is no apparent reason for countersinking the dental chair into the floor w ith the euthenics concept. ■ O pera tin g lights sh o u ld be m o u n te d in th e ceil ing: Because operating lights structurally involve relatively heavy weights th at hang with cantilevered design, m inor vibrations are magnified to affect the light stability. C eiling-m ounted o perat ing lights are superior and m ore esthetic through elim ination of upright m ounting arms that add to the “m onster im age” of the past dental equipm ent design. O perating lights m ounted to the dental chair are unstable and vibrate w hen the patient moves. ■ T h e d en ta l e n v iro n m e n t sh o u ld be w ell orga n ized, esthetic, p ea c efu l, a n d ha p p y: T raining m anuals of office program m ing can do m uch to sta bilize policy and operating procedures th at stim u late efficiency and im prove the happy environm ent of the auxiliary personnel. This happiness and obvious organization in w orking habits encour age and inspire patien t confidence.
Sum m ary M axim um use of dental equipm ent can be en joyed only if designs are founded on principles that fit the needs of the operating dentist o r dentist-assistant team . T hese principles m ust apply to all operating variables and m ust serve the patient by m eeting operating needs of dental p er sonnel. E ach piece of dental equipm ent m ust be considered an integral p art of the whole in both design and function, thus requiring the rudim ents governing instrum ent design to be bro ad in scope to include concept planning. T he 26 principles presented in this p ap er are not all-inclusive. C onsideration of these elem ents, how ever, together with their supporting logic, can help to stabilize present and future planning of dental equipm ent to the advantage of the dental profession, dental industry, and the patients who ultim ately benefit from efficient dental service. Doctor Thom pson's address is 3535 H illsid e Lane, S a lt L a k e C ity, 84109. 1 . W e b s te r's seventh new collegiate dictionary. Sp ring field, M ass., G. & C. M e rria m Co., 1961, p. 286. 2. Thom pson, E. O. C lin ic a l application of the washed fie ld techn ic in dentistry. J A D A 5 1 :7 0 3 Dec., 1955.
716 ■ JA D A , Vol. 74, March 1967
Fig. 9 * Dentist-assistarit team efficien cy with m inim al stress
seated
for
operating
Fig. 10 ■ P a tie n t rests on euthenics dentistry neckrest th a t properly orients head to torso to m inim ize gagging and swallowing reflexes. P a tie n t's o cciput is cradled to allo w head to rotate laterally w ith firm support for e ffi cie n t operating position. Housed roll of waxed paper conveniently provides fresh cover for each patien t
Principles of efficient dental equipment use Elbert O. Thompson, DDS, Salt Lake City
Ideal operating objectives of the prudent and conscientious dentist require that his training, his skills, and his operating environment serve his patients efficiently. The dentist’s training and skills are paramount in importance, but these qualifications are enhanced or diminished by his operating environment that includes his tools and equipment. A personal equation in this environ ment is vital to his efficient performance, but some basic principles can be applied to all types of dental practice.
General considerations * D en tist’s operatin g needs: Engineering, manu facturing, advertising, and merchandising specifi cations have influenced dental equipment design. The resulting production of dental equipment does not always meet the operating needs of the den tist. This paper attempts to relate the dentist’s operating needs to the equipment that is created to serve these needs. 708
■ N e e d fo r concept-thinking: If a piece of den tal equipment is to be effective, it must be coor dinated with all other equipment in the office. It would not be logical to design a dental unit inde pendent of the dental chair, the dental operating stool, or the dental cabinet. A ll pieces of equip ment must be part of a single concept since their design and function are interdependent.
■ H appin ess an d efficiency: Because efficiency in function is the ultimate objective in the design of equipment, it is important that facets that promote an environment of happiness, peace, and efficiency for the patient and dental operating team are in corporated in design principles. A progressive appraisal of principles must not be influenced by a reckless desire to change or by marketing or manufacturing patterns that are linked to the past unless these patterns are ob jectively based on principles that will always pro mote effective dentistry. Proper placement of equipment components for
proficient use saves tim e an d effort and offers m ini m al interference w ith operating m otion patterns. Simplicity of design contributes to rapid, easy cleaning and disinfection. A utom ation, w herever possible, m inim al weights, torques, and bends in the use of an instrum ent reduce stress. A preplanned design w ith proper placem ent of equipm ent, supplies, and instrum ents reduces tension and adds to the happiness and efficiency of the operating environm ent.
D efinition of terms ■ O perating ovoid: T he operating ovoid is the region w here all instrum ents and equipm ent used in treatm ent are located. D u rin g treatm ent, the patient’s head is located in the center of this region w here all instrum ents and equipm ent can be efficiently reached by the operating dentist and his assistant. D uring treatm ent, the patient’s head is located in the center of this region.
Fig. 1 ■ Euthenics dentistry m obile unit m anifold a t tach ed to dental chair. Dynam ic instrum ents are housed in m anifold and go up and down w ith ch a ir and slide b ack and forth to m eet operating variab les
■ O perating variables: Properly designed dental equipm ent m ust efficiently serve the following operating variables: 1. E ach patient, no m atter w hat his physical build o r height, m ust be served com fortably in varying positions. 2. T he dentist should be able to w ork efficient ly alone o r with one or m ore chairside assistants. 3. T he dentist and assistant should be able to w ork efficiently in a standing o r sitting posi tion. ■ Sta n d -u p den tistry: This term applies to the concept of having the dentist stand behind the patient, w orking with slow-speed rotary and hand cutting instrum ents, and using indirect vision by m eans of the m outh m irror. ■ S it-d o w n d entistry: This term applies to the concept of having th e patien t recline in a con toured dental chair and having the dentist and assistant sit com fortably on operating stools close to the patient’s head so th at they can w ork with direct or indirect vision. T h e dentist should be able to operate not only from a sitting but also from standing position w ithout equipm ent design dictating posture com prom ise. ■ E u th en ics: This term is derived from the G reek, euthenia, w hich m eans well-being, and from the term , euthenein, w hich m eans to thrive.
Fig. 2 ■ M o b ile operating cab inet serves dentist or assistant in seated or standing positions. It contains static instrum ents, im m ediately needed supplies. X - ra y view box, am algam ato r, tim er, and so forth. Top w o rk ing surface serves as operating tra y and positions tim e and motion drug tray. A s m any as 1,200 items can be e fficie n tly organized for im m ediate use in cab in et by either member of operating team
Thompson: EFFIC IENT DENTAL EQ UIPM EN T USE ■ 709
W ebster’s New Collegiate D ictionary1 (1 9 6 1 ) defines “euthenics” as “The science having to do with the betterm ent of living conditions to secure m ore efficient hum an beings.” ■ C om ponent instrum ents: T hese are instru m ents used by the dentist-assistant team . They are assigned to one of the three groups as follow: 1. D ynam ic instrum ents (Fig. 1) include those instrum ents with cord, hose, or tube attachm ents. 2. Static instrum ents (Fig. 2 ) include all hand instrum ents. 3. Im m ediate operating supplies (Fig. 2 ) in clude m inim al supplies and articles needed for operation. ■ M anifold concept: (Fig. 1, 3) T he m anifold concept is a new idea in dental unit design th at m akes dynam ic instrum ents accessible from the front-left of the patient so that these instrum ents
are related to the patient’s head throughout all operating variables. No instrum ents, trays, or brackets are positioned over the patient. ■ Evacuative system : This system is an effec tive m ethod of evacuating liquids and solid debris from the patient’s m outh by m eans of a powerful but gentle negative airstream . This system filters the liquids from the solids and separates them from the negative airstream . A clean, clear, washed operating field is m ade possible. This evacuative system and its use are term ed “washed-field den tistry.”2 ■ Saliva cross-contam ination: This term refers to the spread of bacteria in the patient’s saliva by the o p e rato r’s hands and instrum ents. ■ Cuspidor calisthenics: M ovem ent of the p a tient to and from the dental cuspidor.
Fig. 3 ■ Euthenics dentistry concept places p a tien t's head in cen ter of operating ovoid. D yn am ic instrum ents at front left of patient in m obile dental unit m anifold are a v a ila b le to both members of operating team . S tatic instrum ents and im m ediately needed supplies are provided in mobile operating cab inet behind patient. P a tie n t and operating team sit com fo rtab ly with m inim al stress. No instruments, trays, and so forth are over top of p atien t to interfere with operating motion patterns or to endanger safety o f patient 710
■ JAD A, Vol. 74, March 1967
Principles ■ D e n ta l e q u ip m e n t m u s t fu n c tio n efficiently to m e e t im m e d ia te e q u ip m e n t n eeds th ro u g h all o p er a ting variables: T he dentist’s efficiency is chal
lenged if there is w asted m otion in reaching com ponent instrum ents from the operating stool or from a standing operating position. T herefore, it is im portant th a t dental equipm ent provide all com ponent instrum ents for ready use throughout all operating variables. ■ A ll c o m p o n e n t in stru m e n ts m u st be im m ed ia tely available to b o th d en tist a nd chairside assistant d u rin g all operative variables: Two designs in dental equipm ent have attem pted to m eet this re quirem ent: 1. Designs th at require the patient to be m oved to the com ponent instrum ents are built around the fixed dental unit th a t houses and serv ices varying num bers of com ponent instrum ents. This equipm ent em bodies the basic design that has served stand-up dentistry in the past. Bracket tables with service trays for some static instru m ents have been planned for use over the patient seated in the dental chair. W hen sit-dow n dentistry was introduced, the seated dentist could not conveniently reach his instrum ents on the fixed dental unit. Therefore, the dental chair track concept was designed to allow th e dentist to m ove the patient forw ard. T he distance betw een these instrum ents and the patient’s head was shortened. This d ental chair track concept had m any disadvantages: when the patient was seated in the dental chair and the den tal ch air was m oved on the dental ch air track, the operating light, the foot control, the dentist’s operating stool, the assistant’s operating stool, and the bracket table o r operating cabinet had to be relocated. A lso, the related dental cabinets th at contained static instrum ents o r needed im m ediate supplies had to be moved. E ach m ove m ent had to be m ade m anually. A com plex pat tern of cross-contam ination developed. T here fore, operating cleanliness required disinfecting and hand-w ashing procedures each tim e the pa tient was moved. T he dental chair track produces interference in relating the foot control and the operating stools to the patient. C asters cannot easily move over the m etal tracks behind the forw ard-posi tioned dental chair. 2. T he equipm ent th at is designed to bring the com ponent instrum ents to the patient allows the
patient to be positioned in any operating variable, and the dynam ic instrum ents are brought to the patient through the m anifold concept design (Fig. 1, 3 ). Similarly, static instrum ents and im m edi ately needed supplies, all contained in the mobile operating cabinet (Fig. 2 ) can be positioned directly behind the patient so as to be convenient to each m em ber of the operating team. ■ D e n ta l e q u ip m e n t sh o u ld b e d esig n ed to bring a ll co m p o n e n t in stru m en ts, sta tic in stru m en ts, a n d im m ed ia te o p era tin g su p p lies to w a rd or aw ay fr o m th e p a tien t, w h o se o p era tin g p o stu re re m a in s a lm o st co n sta n t in th e ce n te r o f th e o p era t in g o v o id (Fig. 3 ). ■ A co m p le te c o m p le m e n t o f c o m p o n e n t in stru m e n ts sh o u ld b e in clu d ed in th e o p era tin g o vo id e q u ip m e n t to se rve th e n eed s o f th e operating d en tist: Past developm ents in dental equipm ent have resulted in a confused hodgepodge of con trols, cords, and tubes. A n efficient operating procedure would not require any m em ber of the operating team to procure, plug in, or attach a com ponent instrum ent before use o r unplug o r detach and return a com ponent instrum ent to storage position after use. M axim um use of dental equipm ent can be ex pected only through the kind of sm oothly func tioning design th a t perm its use w ithout interrupt ing the operation (Fig. 1 ). A n efficient design would provide esthetic housing, constant attach m ent for easy use, and autom ation for all com ponent instrum ents that are used reasonably often. ■ E q u ip m e n t in th e tre a tm en t region sh o u ld be in o ffen sive in a p p earance a n d as esth etic as p o s sible. I t sh o u ld contain, rather th a n m ere ly su p port, as m a n y o f th e c o m p o n e n t d y n a m ic in stru m e n ts as po ssib le: Unsightly cords, hoses, tubes, m otors, trays, and bracket arm s need not becom e a “m onster” th at upsets the patient psy chologically. Efficient housing and organization of effectively placed instrum ents add to the eu thenics concept and minimize the visual stress (Fig. 4 ) . ■ D y n a m ic in stru m en ts sh o u ld be accessible to th e p a tie n t’s m o u th fro m th e 5 o ’clo ck to th e 6 o ’clo ck p o sitio n zo n e: W ork simplification studies have established an operating zone for the dentist th at allows his hands and arm s freedom of m ovem ent between the 6 o ’clock and 11 o ’clock po Thompson: EFFICIENT DENTAL EQ UIPM ENT USE ■ 711
dental chair is raised or lowered and slide back and forth in a horizontal position to accom m odate operating variables (Fig. 1 ): The m anifold ar rangem ent, easily repositioned, provides that dy nam ic instrum ents can be constantly related to the patient’s m outh through even extrem e operat ing variables and can be available to both dentist and assistant w hether they are seated or standing. ■ E quipm ent design should, wherever practical, provide autom atic activation and deactivation of dynam ic instrum ents to elim inate m anual switch manipulation: This autom ation principle, in com bination with the modified manual-switching or foot-switching design, saves motions involved in reaching for switches while the dentist’s at tention is focused on his work. It also minimizes saliva cross-contam ination with required disinfec tion procedures. Fig. 4 ■ Euthenics dentistry drawer under ch a ir e ffe c tive ly uses space under foot of dental chair. Electric surgical instruments, photographic equipm ent, and so forth can be housed in drawer. Electric power can be a u to m a tic a lly turned on as drawer opens and turned off as draw er closes
sitions. The dental assistant has freedom of hand and arm m ovem ent from the 1 o’clock to the 5 o ’clock positions. T hus, the area betw een the 5 o ’clock and 6 o ’clock positions is free for the approach of dynam ic instrum ents w ithout interfer ing with the m otion patterns of the dentist or those of his assistant. ■ Cords, hoses, and tubes attached to dynam ic in strum ents should be as short, as light in weight, as torque-free, and as bend-free as operating lim its will allow during use: E xperim ents have show n th at the m anifold concept (Fig. 1) p ro vides an efficient rem edy for the aforem entioned principles. ■ Instrum ents, dynam ic or static, should not be placed over the patient while he is in the dental chair: Patient welfare is the objective of all conscientious dentists. Instrum ents and m aterials should not be positioned over the patien t’s body and during use should be guided around, not over, the patien t’s head to minimize accident hazards. Efficient arrangem ent of dynam ic instrum ents can be m ade to function effectively in the m anifold concept (Fig. 3 ). ■ D ynam ic instrum ents should be so related to the dental chair that they go up and down as the 712 ■ JA D A , Vol. 74, March 1967
■ The turbine variable foot control should be ori ented. and stabilized for im m ediate availability. The operator or chairside assistant should not need to search for or m anually position this foot control for use in any operating variable position: D uring the dental operation, the dentist must change his operating position frequently and often rapidly to com plete an operation efficiently. C on ventional foot controls have had to be manually m oved as operating positions change. The euthen ics dentistry concept provides that the foot control can be recessed and fixed to the base of the mobile operating cabinet (Fig. 2 ) so that it is stabilized in constant relation to the cabinet and can be easily seen by the operator and efficiently used. This arrangem ent has the additional advan tage of elim inating unsightly, unclean, and unsafe foot control cords from the treatm ent region. ■ Floor channels or crawl space underneath the floor should be provided for m odern dental equip m ent installation in office planning: Expense of installation in drilling floors and providing service, tubing, wire, pipe, and so forth can be reduced to a m inim um with intelligent advance planning and is insignificant com pared to advantages gained in efficient operation. New equipm ent that might be designed in the future should also be anticipated in the plans. ■ Static instrum ents and im m ediately needed sup plies should be contained in the m obile dental operating cabinet that should be located behind
«r
m otion and vision. The seated posture of dentist and assistant changes since operating needs neces sitate varying positions and postures. A n efficient stool will com plem ent and not hinder these oper ating posture requirem ents.
Fig. 5 ■ Euthenics dentistry operating stools support dentist and assistant with foot support and torso support with ve rtical height adjustm ent of seat possible w ithout m anual controls
the patient for m ost efficient operation (Fig. 2 ) : Because the chairside assistant frequently pro cures and returns static instrum ents during an operation, her right hand is positioned to reach for and replace instrum ents w hen the operating tray is placed on top of the mobile operating cabinet behind the patient. M obility of the mobile operating cabinet is im portant to ensure proper use of all static instrum ents and supplies. T he operating cabinet should be designed with spe cially constructed “tim e and m otion” inserts to contain, ready for im m ediate use, as m any as 1,200 items necessary in the average dental practice. * Operating stools for dentist and assistant should provide for instantaneous variations in height w ithout m anual adjustm ent and should provide body support for cantilevered operating postures and an elevated fo o t rest (Fig. 5 ) : The ideal operating stool should support its own weight on a base designed for sm ooth, gliding movem ents w ithout tipping hazards and should be designed to provide instantaneous changes in vertical seat ing levels w ithout m anual adjustm ent. T he assist ant should sit higher than the dentist to assist effectively w ithout interfering w ith his operating
■ O nly equipm ent necessary for efficient, organ ized operating procedures should be placed in the treatm ent region. This treatm ent region should not be used for storage of item s that are not used reg ularly: T he euthenics dentistry wall secretary (Fig. 6 ) organizes patient’s records for preplan ning operating procedures by presenting patient’s records and radiographs for study before the p a tient is seated. A ny im portant negative history can readily be considered for m ore efficient dental service. All records for the day’s operation can be organized, posted, and controlled through p roper use of dental equipm ent. C om ponent instrum ents seldom used and sup plies in excess of actual operating needs should be organized and stored conveniently close to, b u t outside, the operating region. ■ D ental equipm ent should be designed to func tion as quietly as possible. Necessary noise should be camouflaged: Noise can be controlled by proper location of m otors, telephones, and so forth. T reatm ent regions should be sound-treated with acoustical tile in ceiling, drapes on windows and, when desired, carpet on the floor. Softsoled shoes should be worn by operating team m em bers, and conversation should be as quiet as possible. Background music, w hen restful, is recom m ended. M usic can be especially effective when com bined with dental education and psychological conditioning program s w hen directed to the p a tient by m eans of lightweight, com fortable-fitting, and high-fidelity stethoscope earphones (Fig. 7 ). These program s can be controlled by m eans of the epic center, which can be located in the face of the euthenics dentistry m obile unit m anifold (Fig. 1, 7 ). ■ Unpleasant odors should not be noticeable in the dental office: Properly designed and effi ciently used evacuative systems can do m uch to protect the patient and the operating team from offensive m outh odors that occur during the oper ation. O dorous drugs should be kept in sealed containers. A thorough disinfection and cleaning program is also vital to the p roper control of Thompson: EFFIC IENT DENTAL EQ UIPM EN T USE ■ 713
Fig. 6 ■ W a l l secretary can be m ounted on right treatm en t w all. W a ll secretary provides space for patien t records, X - ra y view box, pull-down w ritin g desk, models for patient ed u ca tion and case presentation, telephone, an d intercoms
odors. W aste receptacles outside the treatm ent region can be effectively planned to reduce further unpleasant odors. ■ D en ta l e q u ip m e n t sh o u ld be d esig n ed so all ex te rn a l a n d internal p a rts are readily accessible fo r installation a n d service (F ig. 8 ) : Access panels th at can be easily rem oved to expose in ternal equipm ent parts that need to be reached for installation and service are vital to efficient equipm ent planning. ■ D en ta l e q u ip m e n t sh o u ld be d esig n ed to fit in th e sm a ll o p era to ry as w ell as in the large operatory. T he euthenics dentistry concept creates a self-contained operating island th at effectively ful fills this principle. 714 ■ JA D A , Vol. 74, March 1967
■ C o n tro ls s h o u ld b e p ro v id e d in d en ta l u n it d e sign th a t en a b le th e d en tist to a d ju st air p ressu re a n d vo lu m e , w a ter p ressu re a n d vo lu m e , a n d oil d rip ra tes to d esired standards: It is vital to the proper function of these instrum ents, as they re late to the m anufacturer’s instructions, th at they can be easily adjusted to the operator’s desires for m axim um perform ance. ■ E q u ip m e n t design sh o u ld p ro v id e e v ery n ee d ed fa cility to e m p ty the p a tie n t’s m o u th co m fo r ta b ly a n d efficiently: By the washed-field dentistry principles th at use the 10-mm. m outhpiece and hydroceptor, liquids and solids can be instantane ously evacuated from the patient’s m outh to en able the dental operation to proceed efficiently.
drain autom atically into the sewer line, and the solids should accum ulate so they can be disposed of o r so their precious m etal value can be re claim ed. T he separating system should be easily disassem bled for cleaning and disinfecting so bac terial grow th with accom panying odors can be controlled. ■ T h e d en ta l chair b a ck sh o u ld be as th in as p o s sible: A dental chair with a thin back allows the p atient’s head to be placed in the dentist’s lap fo r m axim um operating efficiency w hen the dentist is in a seated position (Fig. 9 ). T he euthenics dentistry neckrest should sup po rt the p atient’s head in its norm al relation to the torso, regardless of operating position or size of patient (Fig. 1 0 ). This position helps to reduce problem s related to gagging and swallowing re flexes. Fig. 7 ■ Epic center in face m obile unit m anifold controls which play-b ack instrum ents can m aterial or en tertain m en t during histories, patien t instruction, or also be recorded through control
of euthenics dentistry five chan nels through relay p atient education dental treatm ent. Case case presentation can system
If a conventional cuspidor is advantageous, in addition to the evacuative system, it should not occupy critical space th at is needed by the assistant, and it should be out of sight w hen n o t in use and autom ated w ith w ater flow w hen brought into function. E uthenics dentistry provides (Fig. 1, 3) an autom ated evacuative m outhpiece th at can be used by the dentist, by the assistant, or by the patient him self to rem ove liquids o r solids from the patient’s m outh. If this m ethod is used, a con ventional cuspidor o r a funnel into which the p a tient could em pty his m outh w ould not be needed. C uspidor calisthenics that interfere with efficient operating program s can therefore be elim inated.
■ D e n ta l chair base design n eed n o t allow fo r co u n tersin kin g in to th e floor: T he dental chair,
Fig. 8 ■ Euthenics dentistry fixed unit foun tain head houses all services to d ynam ic instruments, volum e con trols, pressure controls, filters, oilers, and tubes, which are read ily a v a ila b le for service since top and sides open com pletely
■ E va c u a tiv e e q u ip m e n t sh o u ld be d esig n ed w ith an a u to m a tic separating a n d filtering sy ste m th a t can be d isa ssem b le d fo r fre q u e n t cleaning a n d that can fu n c tio n as p a rt o f th e d en ta l unit: Solids and liquids m ust not be draw n into m ain air lines since these air lines becom e bacterially contam i nated. Sludge and bacterial contam inated masses build up to becom e deterrents to efficient airflow. Solids and liquids are preferably separated from the functioning negative airstream in a separating system located in the dental unit. L iquids should Thompson: EFFIC IEN T DENTAL EQ UIPM ENT USE ■ 715
w ith the patient in a supine operating position, will need to be raised to m ake room for the o p er ating team ’s knees (Fig. 9 ) . T here is no apparent reason for countersinking the dental chair into the floor w ith the euthenics concept. ■ O pera tin g lights sh o u ld be m o u n te d in th e ceil ing: Because operating lights structurally involve relatively heavy weights th at hang with cantilevered design, m inor vibrations are magnified to affect the light stability. C eiling-m ounted o perat ing lights are superior and m ore esthetic through elim ination of upright m ounting arms that add to the “m onster im age” of the past dental equipm ent design. O perating lights m ounted to the dental chair are unstable and vibrate w hen the patient moves. ■ T h e d en ta l e n v iro n m e n t sh o u ld be w ell orga n ized, esthetic, p ea c efu l, a n d ha p p y: T raining m anuals of office program m ing can do m uch to sta bilize policy and operating procedures th at stim u late efficiency and im prove the happy environm ent of the auxiliary personnel. This happiness and obvious organization in w orking habits encour age and inspire patien t confidence.
Sum m ary M axim um use of dental equipm ent can be en joyed only if designs are founded on principles that fit the needs of the operating dentist o r dentist-assistant team . T hese principles m ust apply to all operating variables and m ust serve the patient by m eeting operating needs of dental p er sonnel. E ach piece of dental equipm ent m ust be considered an integral p art of the whole in both design and function, thus requiring the rudim ents governing instrum ent design to be bro ad in scope to include concept planning. T he 26 principles presented in this p ap er are not all-inclusive. C onsideration of these elem ents, how ever, together with their supporting logic, can help to stabilize present and future planning of dental equipm ent to the advantage of the dental profession, dental industry, and the patients who ultim ately benefit from efficient dental service. Doctor Thom pson's address is 3535 H illsid e Lane, S a lt L a k e C ity, 84109. 1 . W e b s te r's seventh new collegiate dictionary. Sp ring field, M ass., G. & C. M e rria m Co., 1961, p. 286. 2. Thom pson, E. O. C lin ic a l application of the washed fie ld techn ic in dentistry. J A D A 5 1 :7 0 3 Dec., 1955.
716 ■ JA D A , Vol. 74, March 1967
Fig. 9 * Dentist-assistarit team efficien cy with m inim al stress
seated
for
operating
Fig. 10 ■ P a tie n t rests on euthenics dentistry neckrest th a t properly orients head to torso to m inim ize gagging and swallowing reflexes. P a tie n t's o cciput is cradled to allo w head to rotate laterally w ith firm support for e ffi cie n t operating position. Housed roll of waxed paper conveniently provides fresh cover for each patien t