The efficient exchange of instruments between the operator and the dental assistant is fundamental tothe facilitation of an efficient and stress-free dental practice. This requires a commitment on the part ofthe members of the operating team to specific work practices before and during a dental procedure.The objectives of this article include the description of team member responsibilities during an instru-ment transfer and the identification of the benefits of a proper instrument transfer technique. Objectivesalso include specific instrument grasps and descriptions of transfer methods that require practice on thepart of the operating team in order to attain proficiency .

Keywords: Instrument transfer, single-handed transfer, two-handed transfer, hidden syringe transfer,pen grasp, modified pen grasp, palm grasp, palm thumb/thumb-to-nose grasp.

1The Journal of Contemporary Dental Practice, Volume 2, No. 1, Winter Issue, 2001

Volume 2 Number 1 Winter Issue, 2001

Abstract

Four-Handed Dentistry: Instrument Transfer

© Seer Publishing

2The Journal of Contemporary Dental Practice, Volume 2, No. 1, Winter Issue, 2001

IntroductionInstrument transfer is the process of transferringinstruments and materials to and from the opera-tor, within the transfer zone, at a precise momentof need. (Figure 1) An important pre-requisite tosuccessful instrument transfer is the ability ofeach member of the dental team to understandthe procedure and anticipate each other's needs.Use of an efficient instrument transfer is one ofthe basic skills every dental team must learn inorder to be productive and stress free. Thisnotion may seem basic, yet many dentists andassistants struggle to refine a smooth productivetechnique.

During the past twenty-five years there has beena diminished emphasis on formal education in thebasic principles of the four-handed dentistry con-cept including the use of efficient instrumenttransfer techniques. This has resulted in dentistsnot learning proper ergonomic strategies in dentalschool, or following graduation due to fewer con-tinuing education courses being offered on thesubject. These dentists tend to work more inef fi-ciently and engage in more time consumingmovements during dental procedures than is nec-essary. Proper instrument transfer techniquesserve to conserve motion, increase the flow of theprocedure and reduce eyestrain by eliminatingthe need to look away from the brightly illuminat-ed operative field during the transfer. It is advis-able to re-evaluate the instrument transfer tech-niques used during a dental procedure in order toensure safety during the transfer and ensure thatthe benefits of a proper technique (listed below)are realized.

• The operator is able to maintain vision onthe operative field thus reducing eyestrainassociated with changing light intensityand focal length accommodation.

• The operating team conserves time andmotion during instrument transfers.

• There is a reduction in stress and strainon the operating team due to the uninter-rupted flow of the procedure without thenagging delays associated with locatingand delivering instruments if an orderlysystem is not used.

• When instrument transfer is used in con-junction with the oral evacuator and theair/water syringe, the operative site willalways be clean and the next instrumentwill be ready for use.

• Percutaneous injuries associated withuse of dental instruments can be mini-mized using a prescribed transfer tech-nique.

Team Responsibilities During InstrumentTransfer

Basic Principles Successful instrument transfer is predicated on aset of principles that require organization andplanning in advance. The first step in thisprocess is to work from a well-defined treatmentplan so that instruments and materials requiredfor a planned procedure can be prepared inadvance. Dental assistants should thoroughlyunderstand the procedure to be performed inorder to anticipate the sequence in which theinstruments and materials will be used. Withthis knowledge the dental team can develop astandardized routine for the performance of mostdental procedures.

Additional strategies such as the delegation of allmaterial preparation and instrument transfer tothe assistant as well as the delegation of expand-ed/advanced functions to legally qualified assis-tants will maximize the use of the dentist's time.Using ergonomically designed equipment andplacing the patient in a supineposition improvesaccess and visibility for the operating team.(Figure 2) Placing supportive equipment andsupplies within a 21-inch radius of the assistant'shands as well as confining movements to the oralcavity and the adjacent transfer zone over the

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patient's chest will result in the conservation oftime and motion during the procedure.

To ensure a successful instrument transfer, eachmember of the team must assume specific, butoften related responsibilities.

Operator RequirementsIn order to maximize the efficiency of an instru-ment transfer technique the operator shouldmaintain a finger rest for his/her working hand inthe oral cavity so that the actual location of thetransfer between team members will be pre-dictable. Such predictability is essential forsmooth, safe transfers to occur.

A non-verbal signal to indicate a need toexchange an instrument is helpful in order toavoid tedious and repetitious verbal communica-tion throughout the workday. It is not uncommonfor the number of instrument exchanges during atypical restorative procedure to exceed one hun-dred. After the non-verbal signal is given, theoperator needs to place the used instrument inhis/her hand in a position that enables the assis-tant to safely retrieve it and transfer the newinstrument. A simple withdrawal of the usedinstrument from the operative field can serve as anon-verbal signal and it repositions the usedinstrument for better access by the dental assis-tant. (Figure 3)

To reduce eyestrain the operator needs to main-tain his/her eyes on the operative field and refrainfrom removing instruments from or replacinginstruments onto the pre-set tray. By making aninstrument exchange predictable there is no need

for the operator to look away from the oral cavityduring the procedure.

Assistant RequirementsIn order to maximize the efficiency of an instru-ment transfer technique the assistant needs tomaintain instruments on a pre-set instrument trayin the sequence of their use in order to facilitaterapid location of needed instruments during a pro-cedure. (Figure 4) The assistant also needs toanticipate the need for the next instrument andstay alert for any change in the procedure to beready to modify the sequence of instrumentswhen necessary.

As the instrument transfer begins, the workingends of instruments need to be positioned for theproper dental arch; up for the maxilla and downfor the mandible. During the transfer the assis-tant needs to use positive pressure to ensure theoperator senses that the instrument has been

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delivered; this eliminates the operator from look-ing away from the site, or fumbling the deliveredinstrument. Immediately after the transfer debrisfrom the used instrument should be removedbefore returning it to the tray or to the operator foruse again.

Team RequirementsIn order to maximize efficiency and safety duringan instrument transfer it is advisable for the oper-ating team to observe patient movement, espe-cially during the exchange of an anestheticsyringe or other sharp instruments.

Following a safe standardized transfer procedureshould be used to avoid injuries. Safe techniquesinclude the maintenance of firm control of theinstrument at all times, exchanging instrumentsonly in the transfer zone over the patient's chestand avoiding unpredictable movements during thetransfer. Laying instruments or material on thepatient's napkin should be avoided to preventinjury.

Instrument GraspsThe three most common methods used by anoperator to hold an instrument are the pen grasp,modified pen grasp and palm grasp.

• The pen grasp resembles the positioncommonly used to hold a pen or penciland is widely used for most operativeinstruments. (Figure 5)

• The modified pen grasp is similar to thepen grasp except the operator uses thepad of the middle finger on the handle ofthe instrument. Some operators prefer

this method since they feel it providesmore strength and stability in some pro-cedures.

• The palm grasp is used for bulky instru-ments. It is commonly used for surgicalforceps, rubber damp clampforceps,straight chisels and the air/water syringe.(Figure 6)

• The palm-thumb, or thumb-to-nose graspis used by the assistant for holding theoral evacuator. The operator may usethis with instruments that require a morevertical movement. (Figure 7)

Types of Instrument TransferThe three most common instrument transfersused today in dentistry are the single-handed,two-handed and hidden syringe transfers.

Single-handed Transfer Technique (Right-handed operator)The single-handed transfer is used during mostcommon treatment procedures. (Figure 8) This

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procedure requires that the assistant transferinstruments with the left hand and hold the oralevacuator tip and air/water syringe in the righthand. When working with a left-handed operatorall the positions described here are reversed.

The assistant's hand is divided into two parts: thepick up and the delivery portions. For practicalunderstanding the following discussion defines thefingers of the hand as the thumb, first, second,third and fourth. Some assistants receive theused instrument with only the small finger. Thisaction poses a potentialstability problem and twofingers should be used for retrieval when possible.

Some assistants are tempted to flip or twirl theretrieved instrument back into the delivery portionof the hand. This can pose danger to the patientif the instrument suddenly flips out of the hand.When the used instrument is received from theoperator in the pick up portion of the hand, theassistant can roll the instrument back into positionby pressing the tip of the thumb against the han-dle of the retrieved instrument and rolling it intothe delivery position.

The single handed instrument transfer with a right-handed operator is illustrated in the following pro-cedural outline.

• Assemble instruments in sequence of useand place the instrument tray as close tothe patient as possible. The tray may bepositioned in a vertical or horizontal posi-tion. (Figure 9)

• Place auxiliary equipment such as theanesthetic syringe, or rubber dam on themobile cabinet farthest from the patient.At the beginning of the procedure simul-taneously pass the mirror with the righthand and the explorer with the left hand.(Figure 10)

• Pick up the instrument to be transferredin the left hand and position it betweenthe first finger and thumb at the non-working third of the instrument. (Figure 11)

• Rest the instrument on the middle finger,making certain that the working end ispositioned for the correct arch and posi-tion it within 10-12 inches from the opera-tor's hand in readiness for a transferwhen needed. (Figure 12)

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• The operator signals for an exchange bymoving the instrument being used fromthe tooth and bringing it outside themouth. When possible, a finger rest maybe maintained. (Figure 13)

• The assistant grasps and tucks the usedinstrument toward the wrist with the pickup portion of the hand. (Figure 14)

• The new instrument is delivered into theoperator's hand with the delivery portionof the hand and the operator returns tothe mouth with the new instrument.(Figure 15)

• With the thumb, the assistant rolls theinstrument from the palm up to the ringfinger until it is above the first knuckle.Take care to avoid puncturing the gloves.(Figure 16)

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• Fold the index and middle fingers underthe handle and return the instrument tothe holding position. (Figure 17)

• If the instrument is not to be used again,it can be returned to the proper positionon the tray.

• When the air-water syringe and the oralevacuator are used, the assistant placesthe air-water syringe in the right hand tofree the other for the instrument transfer.(Figure 18)

Bulky instruments can be transferred in the samesingle handed exchange as described above.Many dental units, such as the split unit, prohibiteffective handpiece transfer since the handpieceis outside the 21-inch radius of the assistant'shand. This unit placement leads to decreasedeffectiveness in terms of time and motion. Whena transthorax unit is used and handpieces are

within the transfer zone, the assistant should thenutilize the following procedure:

• The handpiece is made parallel with theinstrument to be exchanged. (Figure 19)

• The return of the handpiece in the pick upportion of the assistant's hand is done inthe same manner as any other instrumenteven though it is bulkier. For this reason,the two fingers used in the pick up methodprovide greater stability. (Figure 20)

• The handpiece is then returned to thedental unit

The Two-Handed TransferThe two-handed transfer is used when transfer-ring bulky instruments such as the rubber damclamp forceps or surgical forceps. (Figure 21)This transfer requires the assistant to pick up theused instrument with one hand and deliver thenew instrument with the opposite hand. This

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exchange requires more movement and limits theuse of the HVE and air-water syringe.

Hidden Syringe Transfer The hidden syringe transfer is named as suchbecause it takes place out of view under the chinof the patient. It enables the operator to receivethe anesthetic syringe safely and out of thepatient's line of sight thus avoiding undue patientstress. This transfer also occurs within the trans-fer zone.

This transfer requires that the assistant and oper-ator plan in advance the technique to avoid thepotential of a needle-stick. Often the operatorprefers to transfer the instrument behind thepatient. This area is outside the transfer zone,causing the assistant to use a Class V movementand violate safe transfer. This transfer can beadapted to the use of wand type anesthesia veryeffectively. Care should be taken that the baseunit is located nearby the assistant for easyaccess. Using a traditional anesthetic syringe thefollowing steps may be followed:

• A 2 x 2 gauze is passed to dry the site.Topical anesthetic may be applied with acotton-tipped applicator if desired.(Figure 22)

• The protective cap on the needle is loos-ened slightly. (Figure 23)

• The syringe is held in the assistant's righthand when assisting a right handed oper-ator while the assistant stabilizes theoperator's hand using a firm grasp.(Figure 24)

• The operator positions the right handupright with the index, and middle fingers

extended along with the thumb to receivethe syringe. While the assistant holds theoperator's right hand firmly the thumb ringof the syringe is positioned over the oper-ator's thumb and lowered to rest betweenthe awaiting index and middle fingers.

• The assistant's hand carefully removesthe protective cover while maintaining thefirm grasp of the operator's right hand to

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avoid any inadvertent movement. Oncethe cap is removed and the assistant'sright hand is away from the exposed nee-dle the operator's hand can be releasedto signal that the syringe is ready for use.

• The cover is placed into the recappingdevice while the operator administers theanesthetic. (Figure 25) If the patient is asmall child, the assistant can gently placehis or her arms over the child to prevent asudden movement that could result ininjury during the injection procedure.

• The retrieval of the syringe is similar tothe delivery in that, using the left hand,the assistant grasps the operator's righthand upon withdrawal of the syringe fromthe patient's mouth to hold it in a pre-dictable position. The assistant thengrasps the syringe by the barrel to avoidcontacting the contaminated needle. Agauze sponge is exchanged for thesyringe to use as a compress over theinjection site. (Figure 26)

• The syringe is placed in a recappingdevice. (Figure 27) Though it requires amovement out of the operator's zone,some operators prefer to replace thesyringe in the recapping device to avoid apotential accident.

• The mouth may be rinsed at this time ifany anesthetic was dropped on thetongue.

Special Instruments or SituationsThere will be times or situations that dictate modi-fication of the single-handed transfer. The follow-ing suggestions may aid during these times.

Delivery of the Dental Mirror and Explorer(Figure 28 A & B)

• These two instruments are transferredsimultaneously by the assistant at thebeginning of most dental procedures.

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• The dental mirror is picked up by the han-dle end using the right hand. At thesame time the explorer is picked up withthe left hand at the one third of the instru-ment handle nearest the assistant.

• Position the instruments in the deliveryportion of the hands and when the opera-tor signals, pass in the same manner asdescribed in the section above.

• The mirror can be retrieved with the righthand at the conclusion of the procedure.

Use of Non-Locking Tissue Forceps(Figure 29 A-C)

• If non-locking forceps are used, the assis-tant must maintain a grasp on the forcepsto ensure the beaks do not separate dur-ing transfer.

• After the material to be transferred hasbeen placed into the forceps beaks theforceps are paralleled with the usedinstrument that is to be exchanged.

• The instrument is exchanged in the samemanner as other instruments.

• When the forceps are returned to theassistant, the working end of the forcepsis grasped in the palm of the hand toeliminate dropping the contents.

• The forceps are not rolled back into posi-tion, but rather the assistant discards thematerials from the forceps and returnsthe instrument to the tray.

Delivery of Small Items(Figure 30 A & B)

• Small items such as a cotton applicatorcan be passed to the operator as anyother instrument.

• Medicaments can be passed by firstpassing the insertion instrument and thenholding the pad with the medicament inthe transfer zone for easy access to theoperator.

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Delivery of Scissors(Figure 31 A-C)

• The assistant picks up the scissors fromthe tray with the left hand; opens the han-dles slightly and parallels the scissorswith the instrument to be exchanged.

• The operator modifies the hand positionby placing the thumb and first or secondfinger into the rings of the handle.

• The scissors are returned with the beakspointing toward the assistant.

ConclusionUse of standardized instrument transfer tech-niques can yield significant benefits for the oper-ating team. Like most psychomotor skills, prac-tice is required before proficiency can beachieved. The effort required is worthwhile if theteam wants to maximize efficiency, safety andreduce stress throughout the workday.

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2. Finkbeiner BL. Four Handed Dentistry: A Handbook of Clinical Application and Ergonomic Concepts,Upper Saddle River, NJ, Prentice Hall, 2001.

3. Guay A H. Commentary: ergonomically related disorders in dental practice. J Am Dent Assoc.February 1998, 129(2):184-6. No abstract available.

4. Hunk K. Ergonomics: a case study in preventing repetitive motion injuries. Journal Dental SchoolTechnology, June 1996;13(5): 35-7.

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