Dental Ergonomics and Four Handed Dentistry

Question 1

Four-handed dentistry

Question 2

Ergonomics

Question 3

Ergonomics

Answer 3

ÒEfficiency and safety in our profession
ÒPlacement/positioning of equipment and each person on the team for:
ÉMaximum longevity of the each
ÉEfficiency or production
ÉPrevention of injury

Question 4

DAU

Answer 4

ÒDeveloped in the 1960’s.
ÒEmphasized proper positioning of dentist, dental assistant and patient.
ÒIncreases amount of patient care provided while decreasing amount of fatigue and stress on the dental team.

Question 5

Ergonomics

Question 6

Dental Equipment – EFFICIENCY designed

Question 7

– EFFICIENCY designed

Question 8

Principles of DAU

Question 9

Principles of Work Simplification

Question 10

Elimination of Awkward Postures & Movements

Question 11

ÒThighs are :

parallel

Question 12

ÒKeep vertebrae :
ÉNatural
ÒDo not bend neck
ÒDo not twist back

Answer 12

ÒKeep vertebrae :
ÉNatural
ÒDo not bend neck
ÒDo not twist back

Question 13

Balanced Position

Answer 13

ÒTo maintain a balanced position while working, the dentist should be guided by the criteria on the following slides.

Question 14

Postural Criteria – Dentist/operator

Answer 14

ÒThe back should be supported and straight.
ÒAny leaning forward should be done from the hip.
ÒBoth shoulders should be at an equal height and parallel to the floor.
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ÒThe elbows should be down at the sides. Like golf, not wings)
ÒThe forearms and thighs should be basically parallel to the floor.
ÒBoth feet should remain on the floor.
ÒThe lower legs should be perpendicular to the floor.

ÒEyes should be directed downward

rather than looking straight ahead.

ÒThere should be a distance of

14-18” from the dentist’s eyes to

the patient’s mouth.

ÒDecreasing this distance blocks the

light to the patient’s mouth.

Correctly adjusted loupes help to

maintain this distance.

Question 15

Postural Criteria – Dentist/operator

Answer 15

ÒDistance of 14-18” to the patient’s mouth.
ÒBuy and adjust loupes to help to maintain this distance.

Question 16

Postural Criteria – Dentist/operator

Answer 16

ÒAny sustained occupational posture, when unbalanced or awkward, will produce harmful results over an extended period of time, leading to chronic ailments as a result of poor body mechanics.

ÒThe assistant should be seated 6-10” higher than the dentist.
ÒBoth feet should be on the foot ring or foot rest of the dental assistant chair.

ÒThe knees should be placed together parallel the dental chair.
ÒThe abdominal support of the chair should be used to lean forward into the field of operation.
ÒEyes should be directed downward.

Question 17

The Right-Handed Dentist Zones of Activity

OPERATOR’S ZONE

ÒFrom 8:00 to 12:00
Ò11:00 is most commonly used
Ò12:00 is used if working on the anterior segments
ÒMay use 8:00 or 9:00 if the right-handed dentist is working in the lower right quadrant

ASSISTANT’S ZONE

ÒFrom 2:00 to 4:00, with the center being 3:00.
ÒFrom the 3:00 position, the assistant has access to both the static zone and the transfer zone.
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Question 18

The Left-Handed Dentist Zones of Activity

OPERATOR’S ZONE

ÒFrom 12:00 to 5:00.
ÒThe 1:00 position is most commonly used.
ÒThe 3:00 and 4:00 positions sometimes provide greater visibility when working in the lower quadrants.
ÒThe 12:00 position is useful when working in the anterior segments.

ÒASSISTANT’S ZONE – from 8:00 to 10:00, with the center being 9:00.
ÒTRANSFER ZONE – from 5:00 to 8:00.
ÒSTATIC ZONE – from 10:00 to 12:00.
ÒPATIENT’S ZONE – remains the same.

Question 19

STATIC ZONE

ÒFrom 10:00 to 12:00 and 12:00 to 2:00.
ÒUsually just in front of the assistant’s knees.
ÒThe zone of least activity.
ÒOccupied by the assistant’s cart, instruments and infrequently used equipment.
ÒRemains unchanged throughout the procedure.
ÒOnly the assistant enters the Static Zone.

Answer 19

STATIC ZONE

ÒFrom 10:00 to 12:00 and 12:00 to 2:00.
ÒUsually just in front of the assistant’s knees.
ÒThe zone of least activity.
ÒOccupied by the assistant’s cart, instruments and infrequently used equipment.
ÒRemains unchanged throughout the procedure.
ÒOnly the assistant enters the Static Zone.

Question 20

Postural Criteria – Patient

ÒGenerally in a supine position.
ÒExact position is dictated by the quadrant in which the dentist is working.
ÒMAXILLARY ARCH – occlusal plane is perpendicular to the floor.
ÒMANDIBULAR ARCH – occlusal plane is parallel to the floor.

Answer 20

ÒGenerally in a supine position.
ÒExact position is dictated by the quadrant in which the dentist is working.
ÒMAXILLARY ARCH – occlusal plane is perpendicular to the floor.
ÒMANDIBULAR ARCH – occlusal plane is parallel to the floor.

Question 21

Zones of Activity

Answer 21

ÒEach quadrant of the mouth necessitates a definite relative position of the dentist and dental assistant to the patient.
ÒRelative position – uses the numbers on the clock face. The patient’s head is always at the 12:00 position, and the patient’s feet are always at the 6:00 position.

Question 22

Postural Criteria – Patient

Answer 22

ÒUR Quadrant

Supine

ÒUL Quadrant

Supine

ÒLR Quadrant

Elevated 40o from the horizontal

ÒLL Quadrant

Elevated 30o from the horizontal

Question 23

Postural Criteria – Patient

Answer 23

ÒNose and knees of the patient should be in the same horizontal line.
ÒPatient’s feet should be below that line.
ÒIf the patient’s feet are higher than his/her head, the patient may experience orthostatic hypotension when he/she stands up.

Question 24

“I Can’t See Anything!”

Question 25

Motion Classification

Question 26

Motion Classification

Answer 26

ÒClass I – movement of the fingers only.
ÒClass II – movement of the fingers and wrist.
ÒClass III – movement of the fingers, wrist and elbow.
ÒClass IV – movement of the entire arm from the shoulder.
ÒClass V – movement of the entire arm and twisting of the body.

Question 27

Principles of Motion Economy

Answer 27

ÒMinimize the number of body motions.
ÒReduce the length of body motions.
ÒUse smooth, continuous motions rather than zigzag or jerky motions.
ÒPre-position instruments and materials whenever possible.
ÒLocate instruments and materials as close to the point of use as possible.

ÒPlan for the usual, not the unusual.
ÒPosition work surfaces, cabinet tops and trays approximately 2” below elbow level.
ÒUse stools and chairs that permit good posture.
ÒProvide good illumination for satisfactory visual perception.
ÒMinimize the need for refocusing and re-accommodation of the eyes.

Question 28

Preplanned Tray System

Answer 28

ÒFortunately, all of our instruments come on preplanned instrument trays.
ÒA preplanned tray system saves time and money, and requires the following:
ÒInstruments and materials to prepare the trays.
ÒStorage area for prepared trays.
ÒStorage area for used trays.
ÒCentral supply area for disposable items.
ÒPhotos or outlines of tray setups.

Question 29

Color Coding

Answer 29

ÒInstruments should be color coded, using tape, plastic tubing or paint, for easy identification.
ÒDifferent procedures should receive different colors (for example: red for endo, blue for operative, etc.)
ÒOne color should be placed in a straight line along one edge of the instruments.
ÒA different color should be placed in a diagonal line along the other edge of the instruments. This saves time, in that it allows the assistants to set up the correct instruments on the correct trays by lining up the colors. (See the next slide.)
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Question 30

TRANSFER ZONE

ÒFrom 4:00 to 7:00.
ÒOut of the patient’s field of vision, in front of and below the patient’s chin.
ÒInstruments should not be transferred over the patient’s face.
ÒThe zone of greatest activity.
ÒThe only zone that is shared.

Answer 30

TRANSFER ZONE

ÒFrom 4:00 to 7:00.
ÒOut of the patient’s field of vision, in front of and below the patient’s chin.
ÒInstruments should not be transferred over the patient’s face.
ÒThe zone of greatest activity.
ÒThe only zone that is shared.

For Both Right and Left Handed Operators

Question 31

TRANSFER ZONE IS PATIENT’S ZONE

ÒOccupied by the patient’s legs and feet.
ÒIncludes the whole front half of the operatory.
ÒTraffic in the operatory is routed through this zone.

Question 32

Instrument Transfer

Question 33

Rules for Efficient Instrument Transfer

Answer 33

1. The dentist must maintain a third finger (ring finger) rest with both hands throughout the instrument transfer.

ÒMakes the instrument transfer predictable.
ÒReduces the need for the dentist to refocus his/her eyes, thus lessening eye fatigue.Ò

2. The dentist rarely reaches for an instrument.

ÒThe assistant places the instrument into the dentist’s hand, positioned such that it is ready to be used.
ÒThe dentist also never reaches up to adjust the light.
ÒExceptions may be made if the assistant is involved in a more important task.

3. The dentist does not hand an instrument back to the assistant; she removes it from his/her hand.
4. The assistant working with a right-handed dentist passes and receives instruments with the left hand; the assistant working with a left-handed dentist passes and instruments with the right hand.

Question 34

Methods of Instrument Transfer

Answer 34

1. Two-Handed Instrument Transfer

ÒThe assistant working with a right-handed dentist passes with the left hand and receives with the right
Ò The assistant working with a left-handed dentist passes with the right hand and receives with the left.

2. One-Handed Instrument Transfer

The assistant working with a right-handed dentist grasps the instrument being passed with the thumb and first two fingers of the left hand and places it into the operator’s zone parallel to the instrument being used.

Signal exchange

ÒThe signal for exchange is given by the operator when the working instrument is removed from the mouth. This signal is a Class I (fingers only) motion, moving the instrument from the mouth into the transfer zone.
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ÒThe assistant receives the used instrument with the 3rd and 4th fingers of the left hand
ÒPlaces the new instrument into the operator’s hand with the correct working end pointed toward the mouth.

Question 35

Transfer

Question 36

Pen Grasp
ÒPen grasp instruments are those with an angled shank.
ÒInstruments are held like a pen – grasped with the thumb, 1st and 2nd fingers, at the junction of the shaft and the shank, with the working end pointed away from you.
ÒThe most frequently used grasp.
ÒExample: explorer, mirror.

Question 37

Palm-Thumb Grasp

Question 38

Palm Grasp

Answer 38

ÒInstruments are grasped by the handle with the palm of the hand.
ÒExample: Surgical forceps, rubber dam clamp forceps.
ÒRules of instrument transfer do not apply.

Question 39

Bad posture!

Answer 39

ÒThe patient’s chair is raised up too high, thus decreasing the distance between the dentist’s eyes and the patient’s mouth, and forcing the dentist to raise her arms up too high.
ÒA good rule of thumb: when the patient is seated in a supine position, the back of the patient’s chair should be positioned just above the dentist’s legs, allowing the dentist to just move his/her legs under the back of the patient’s chair.

Question 40

Bad posture if maintained for a long time.

Answer 40

ÒThe dentist’s back and legs are in good alignment, but her back is not touching the chair back. It’s OK to lean forward slightly like this in order to see better if you do it for a short time.
ÒIf you do it for a long time, the back muscles will fatigue, so it is always better to let the chair back help support your back by making contact between your back and the chair back.

Question 41

Very good posture!

Answer 41

ÒThe dentist is sitting in a balanced position, as in the illustration.ÒNote: No one expects you to sit perfectly straight and still all the time, but you should return to the balanced position whenever you feel yourself to be “out of balance.”
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