Essentials of 4-Handed Dentistry
Dena 320
Lesson III
Deborah Bell
Major Goal in the Practice of
Dentistry
Deliver high quality service
Deliver service as efficiently as possible
Dental Procedures May Be
Divided Into 3 Parts
Preparation
 Patient treatment
 Clean up

– A second assistant may be utilized to prepare
and clean up allowing first assistant to be
– Full time chairside
– Thus no down time between patients
Concepts important to teamwork
dentistry
Done in seated position
 Patient position
 Work area used
 Operatory equipment
 Availability of second assistant
 Instrument exchange
 Use of oral evacuator

2 Basic Issues of Interest in
Dentistry
Minimizing stress and fatigue for the dentist
 Increase productivity while maintaining
high quality standards

Dentistry is stressful and
fatiguing
Operator must maintain high level of
concentration
 Keep a high level of clinical excellence by
his/her ability to

– Meet variety of patient needs
– Perform delicate skills with limited access
– Manage schedule and the practice
4-Handed Dentistry Reduces
Stress
Increasing efficiency
 Thus increasing productivity to meet
demands of public

Concept of 4-Handed Dentistry
Operating in a seated position
 Employing the skills of a trained assistant
 Organizing every component of the
practice
 Simplifying all tasks to the maximum

3 Major Aspects of 4-Handed
Dentistry
Work simplification
 Motion economy
 Body mechanics

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Motion Economy

Conservation of motion
– Movements consume time and produce fatigue

Eliminate excess harmful motion
Classification of Movements

Class I
– Only fingers
» Signal for instrument transfer

Class II
– Fingers and wrist
» Use of an instrument

Class III
– Finger, wrist and elbow
» Mix amalgam, activating chair buttons

Class IV
– Entire arm from shoulder
» Adjusting light, rubber dam placement

Class V
– Entire arm and twisting of the trunk
Class IV and V
Most fatiguing
 Requires to look away from field then
refocus
 Results: eyestrain and headaches

Class I, II, III
Preferred for DA and Dr
 Involves less muscle activity and saves time
 Allows eye contact concentrated on
operative field

Positioning the Patient and the
Operative Team
Objectives of a Favorable Seated
Position
Access to the operative field
 Good visibility
 Comfort for the operative team
 Relative comfort and safety for the patient

Zones of Activity
Patient in a supine position
Using center of patients face as a
clock
Zones designated as time
Right Handed Operator

Operator zone
– 7 – 12o’clock

Static zone
– 12 – 2o’clock

Assistants zone
– 2 – 4 o’clock

Transfer zone
– 4 – 7 o’clock
Left – Handed Operator

Operator zone
– 12 - 5 0’clock

Transfer zone
– 5 – 8 o’clock

Assistant zone
– 8 – 10 o’clock

Static zone
– 10 – 12 o’clock
Positioning the Operator
Work environment is adapted to the
operator
 Operator positioned first then

– Patient
– Assistant
– equipment
Characteristics of Balance
Posture for Operator
Operators thighs parallel to floor
 Entire surface of seat used to support weight
 Backrest supports back without interference
 Forearms parallel to floor when hands are in
operative position
 Elbows close to the body
 Back and neck reasonably upright with top
of shoulders parallel to floor

Distance of approximately 14 – 18 inches
between the operator’s nose and the patients
oral cavity maintained
 Operative field is operators midline

Positioning the Patient in the
Working Position
Oral Cavity at height of operator’s elbow
 Head placed at upper end of chair and
slightly to operators side of chair
 All patients are seated from the head down

Steps to position a Patient
Adjust back approximately 60 degrees to
vertical
 Raise chair to height patient can easily be
seated
 Raise arm of chair
 Once patient is seated

– Armrest down
– Raise chair approximately 10 inches to allow
Dr. to position himself
Tilt seat portion back so foot rest is raised
approximately 6 to 8 inches
 Lower back of the chair until patient is
about ½ way toward a horizontal position

– Pause to allow patient to adjust

Continue lower chair back until following
relationships exist
– Imaginary line from patients chin to the top of
ankles is parallel with floor
Once seated – Observe Patient
Lying flat with little bending at waist
 Similar to sleep position
 Legs slightly lower than head – if higher
might cause – pt. Anxiety/circulation
problems.
 Patient in supine position

– Plane of the patients forehead is also parallel
with the floor

Lower chair to operators lap
– Approximately 1 inch above knees of operator
Supine Position
Universal position for all working positions
 Patient is lying down facing upwards
 Slight modifications only allowed as
patients needs are assessed

Patient Dismissal
Patient dismissal should be accomplished
by reversing the steps of seating the patient
 Remember to pause for the patient on the
way up as well
 Most important patient dismissal precaution

– Encourage the patient to remain seated to
reestablish their equilibrium
Positioning the Assistant

Must be able to see and have favorable
access to be able to
–
–
–
–
Retract tissues
Evacuate fluids
View to anticipate needs of operator
Maintain clear field
Position of Assistant

3 o’clock position for all quadrants
– Right handed operator

9 o’clock position for all quadrants
– Left handed operator



Stool positioned so edge toward the top of patients
head is in line with the patients oral cavity
Stool as close to chair as possible
Stool elevated to top of assistants head is 4 – 6
inches higher than the dentist
Back erect
 Body support arm adjusted to support upper
body just under rib cage
 If stool positioned properly mobile cart can
be pulled over lap

– Approximately 2 inches below elbows
Work Simplification
Major advantage – Doctors Health
 Definition – finding an easier way to do a
task more efficiently – less pt. Treatment
time spent
 Work simplification studies indicate 4 areas
to make dentistry delivery easier

Rearrangement of instruments and
equipment
 Combination
 Elimination
 Thus simplification

Rearrangement

Position all instruments and equipment in
favorable spot to the team not vice versa to
minimize movements of team
Elimination
Eliminating unnecessary movements,
procedural steps, instruments and
equipment
 Saves time and efforts

Examples of Elimination

Unnecessary bur changes
– 2 handpieces

Unnecessary instrument exchange
– Use instrument to max. before returning

Use supplies and materials that can save
time
– Premeasured capsules

Eliminate seldom used items
– Plan for usual not unusual
Combination
Combining steps
 Combining purpose of equipment and
instruments
 Combining uses

Examples of Combination
Double ended instruments
 Using instruments for more than one
purpose
 Air/water syringe together
 Cements used as base and cementing agent

Simplification
Last because this should occur after all
rearranging, eliminating and combining
activities have been completed
 Basic idea – to minimize number of
variables in all aspects of the practice
 Streamlining process geared to promote
predictable routines in the work pattern

Standardization of Work
Procedures
Contributes to effective teamwork by being
able to anticipate the dentist’s needs
 Contributes to efficiency/production

Examples of Standardization for
Work Simplification
Arrange steps into smooth sequence
 Use preset trays in order of use from left to
right
 More than one op.

– Each treatment room identical in equipment
» And materials
Sit Down Dentistry

Body mechanics/task performance studies
– Seated worker uses 27% less energy
– Seated worker has 17% greater life expectancy
– Production increases from 33 – 78%
Seated in a balance posture concept
 ½ the efficiency of a D.A. Is the result of
working with a well-organized dentist who
practices 4-handed dentistry
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THE
END