Transcript of Dental Hand Instruments
- HAND INSTRUMENT
- presented by Dr Mohammed Sa'ed Fadaly dental student Alazhar
university
- Contantes Instrument grasp Modified pen. Inverted pen. Palm and
thumb. Modified palm and thumb. Non cutting instrument Amalgam
condenser Mouth mirror Others Cleaning and Sterilization
Introduction Definition History Classification Cutting instrument
Non cutting Cutting instrument MATERIALS Hardening and Tempering
Heat Treatments Design Shank angles Nomenclature Formula Bevels
Cutting instrument applications Excavators Chisels Sharpening
Stationary sharpening Mechanical sharpening
- Introduction Definition : It is hand-powered dental
instruments. History : The early hand-operated instruments
characterized by: Large, heavy handles and inferior metal alloys in
the blades. cumbersome, difficult to use, and ineffective in many
situations.
- there was no uniformity of manufacture or nomenclature, Many
dentists made their own hand instruments in an effort to find a
suitable instrument for a specific need. effective sterilization
was a problem. Designs of some early hand instruments
- G.V. Black is credited with the first acceptable nomenclature
and classification of hand instruments. His classification system
enabled both dentists and manufacturers to communicate more clearly
and effectively in regard to instrument design and function. G.V.
Black
- Classification HAND INSTRUMENT cutting Non cutting excavators
chisels others ordinary hatchets hoes Angle formers spoons straight
curved bin-angle Enamel hatchet files scalers carvers Amalgam
condenser mirrors explorers, probes Gingival margin trimmers
others
- Cutting Instrument Hand cutting instruments are manufactured
from two main materials. MATERIALS carbon steel stainless steel Is
harder than stainless steel. remains bright under most conditions.
loses a keen edge during use much more quickly than does carbon
steel when unprotected, it will corrode.
- MATERIALS Tungsten carbide inserts or blades to provide more
durable cutting edges (brittle). They may be soldered to steel
handles. some instruments are made with carbide to provide more
durable cutting edges.
- Stainless Steel Carbon steel Other alloys of nickel, cobalt, or
chromium are used in the manufacture of hand instruments.
MATERIALS
- To gain maximal benefits from carbon steel or stainless steel,
the manufacturer must submit them to two heat treatments: hardening
and tempering . Hardening and Tempering Heat Treatments : Heat
treatment Furnace MATERIALS
- The hardening heat treatment hardens the alloy, but it also
makes it brittle, especially when the carbon content is high. Heat
treatment relieves strains and increases toughness. the tempering
MATERIALS Heating or flaming of hand instruments during dental use
can alter the original properties of the alloy and render it
unserviceable.
- Most hand instruments composed of three parts : Design a- Blade
or nib b-Shank c-Handle
- a- blade This is the working part of the instrument. Begins at
the point which terminates the shank. It is connected to the handle
by the shank. Each blade has a cutting edge which is the working
part of the instrument. It is usually in the form of a bevel (acute
angle) that cuts into the tooth structure. On non cutting
instruments e.g. condensers the part corresponding to the blade is
called the nib or face. Design
- b-shank Connect the handle to the working end of the
instrument. Normally smooth, round and tapered. Design Have one or
more angles to avoid twisting of the instrument. Hand instruments
must be balanced and sharp. Balance allows for the concentration of
force onto the blade without causing rotation of the
instrument.
- Balance is accomplished by designing the angle of the shank so
that the cutting edge of the blade must not be off axis by more
than 1-2 mm. Design Shank angles : Mon-angle, bin-angle, triple
angle . Instruments with small short blades may be monangle
- Instruments with long blades may required two or three angles
in the shank to bring the cutting edge near to the long axis of the
handle. Such shanks are termed contra angled. Design
- c- handle(shaft) It is the part grasped in the operators hand.
Perfectly straight, smooth or eight sided. Serrated for better
gripping and control of the instrument. Design Handles are in
conjunction with the shank or it may be separable. Separate type is
known as cone-socket handle and allows for replacement of several
working ends e.g. mirrors and condensers.
- cone-socket handle (mirror) mirror Design
- Black classified all instruments by name according to: 1.
Function e . g . scaler, excavator . 2. Manner of use e.g. hand
condenser. 3. Design of the working end e.g. spoon excavator,
sickle scaler nomenclature 4. Shape of the shank e.g. mono-angle,
biangle, contra-angle. These names were combined to form the
complete description of the instrument e.g. binangle spoon
excavator.
- Hand cutting instruments have formulas describing the
dimensions and angle of the working end. These are placed on the
handle using a code of three or four numbers separated by dashes or
spaces (e.g. 10-85-8-14). formula The first number indicates the
width of the blade in tenths of a mm (e.g. 10 = 1 mm). The second
number primary cutting edge angle measured from a line parallel to
the long axis of the handle in clockwise centigrade.
- Instrument shank and blade design with formula. formula
- If the edge is perpendicular to the blade, this number is
omitted resulting in a 3 numbers code. The third number indicates
the blade length in mm (e.g. 8 = 8 mm). formula The fourth number
indicates the blade angle relative to the long axis of the handle
in clockwise centigrade e.g. (14) Additional number on the handle
is the manufacturers identification number.
- Additional number should not be confused with the formula
number. formula
- Additional two secondary cutting edges that extend from the
primary cutting edge for the length of the blade. Most hand cutting
instruments have on the end of the blade a single bevel that forms
the primary cutting edge. Two additional edges, Bevels This allows
cutting in 3 directions; facial and lingual walls of the proximal
cavity. Chisel blade design showing primary and secondary cutting
edges.
- Bibeveled instrument have two bevels that form the cutting
edge, e.g. hatched excavator. Bevels
- Single beveled instrument such as spoon excavator and gingival
margin trimmer are used with lateral cutting movement. Bevels
- Enamel hatchet also as a single beveled instrument used with
direct cutting motion, a planning or lateral cutting designated for
right and left to the instrument formula. Bevels
- To determine this, the primary cutting edge is held down and
pointing away. If the bevel appears on the right, it is in the
right instrument of the pair, when used it is moved from right to
left. Right and left bevels Bevels The opposite is true for the
left instrument of the pair. One instrument is used for work on one
side of the preparation and the other for the opposite side of the
preparation.
- The cutting edge is perpendicular to the axis of the handle
e.g. binangle chisel. Bevels Instrument with slight blade curvature
e . g . Wedelstaedt chisel .
- Applications can be classified into: -Removal of caries and
refinement of the internal parts of the preparation. -Used
primarily for cutting enamel. Cutting instrument applications Hand
cutting instrument Excavators Chisels
- CUTTING INSTRUMENT APPLICATIONS (1)Excavators hatchets hoes
angle formers spoons
- CUTTING INSTRUMENT APPLICATIONS It has the cutting edge of the
blade directed in the same plane as that of the long axis of the
handle and is bibeveled . Hatchet excavator
- CUTTING INSTRUMENT APPLICATIONS Hatchet excavator These
instruments are used primarily on anterior teeth for preparing
retentive areas and sharpening internal line angles, particularly
in preparations for direct gold restorations .
- CUTTING INSTRUMENT APPLICATIONS Hoe excavator IT has the
primary cutting edge of the blade perpendicular to the axis of the
handle
- CUTTING INSTRUMENT APPLICATIONS Hoe excavator This type of
instrument is used for planing tooth preparation walls and forming
line angles. It is commonly used in Classes III and V preparations
for direct gold restorations.
- CUTTING INSTRUMENT APPLICATIONS Hoe excavator Some sets of
cutting instruments contain hoes with longer and heavier blades,
with the shanks contra-angled. These are intended for use on enamel
or posterior teeth.
- CUTTING INSTRUMENT APPLICATIONS Angle former excavator It is
mon-angled and has the primary cutting edge at an angle (other than
90 degrees) to the blade. It is available in pairs (right and left
)
- CUTTING INSTRUMENT APPLICATIONS Angle former excavator It is
used primarily for sharpening line angles and creating retentive
features in dentin in preparation for gold restorations. It also
may be used in placing a bevel on enamel margins
- CUTTING INSTRUMENT APPLICATIONS Spoon excavator Its blades are
slightly curved, the shanks may be bin-angled or triple-angled to
facilitate accessibility . - the cutting edges are circular. -the
cutting edges are claw like. Spoon excavators discoid cleoid
- CUTTING INSTRUMENT APPLICATIONS bin-angled spoon triple-angled
spoon
- CUTTING INSTRUMENT APPLICATIONS Cleoid spoon
- CUTTING INSTRUMENT APPLICATIONS Discoid spoon
- CUTTING INSTRUMENT APPLICATIONS (2)Chisels enamel hatchets
gingival margin trimmers straight, slightly curved, or
bin-angle
- CUTTING INSTRUMENT APPLICATIONS straight, slightly curved, or
bin-angle The straight chisel has a straight shank and blade, with
the bevel on only one side. Its primary edge is perpendicular to
the axis of the handle.
- CUTTING INSTRUMENT APPLICATIONS straight, slightly curved, or
bin-angle The shank and blade of the chisel also may be slightly
curved (Wedelstaedt design)
- CUTTING INSTRUMENT APPLICATIONS The shank and blade of the
chisel also may be bin-angled . straight, slightly curved, or
bin-angle
- CUTTING INSTRUMENT APPLICATIONS The force used with all these
chisels is essentially a straight thrust. There is no need for a
right and left type in a straight chisel, since a 180-degree turn
of the instrument allows for its use on either side of the
preparation. straight, slightly curved, or bin-angle
- CUTTING INSTRUMENT APPLICATIONS The bin-angle and Wedelstaedt
chisels have the primary cutting edges in a plane perpendicular to
the axis of the handle and may have either a distal bevel or a
mesial (reverse) bevel. straight, slightly curved, or
bin-angle
- CUTTING INSTRUMENT APPLICATIONS The blade with a distal bevel
is designed to plane a wall that faces the blade's inside surface
straight, slightly curved, or bin-angle
- CUTTING INSTRUMENT APPLICATIONS The blade with a mesial bevel
is designed to plane a wall that faces the blade's outside
surface
- CUTTING INSTRUMENT APPLICATIONS enamel hatchet It is a chisel
similar in design to the ordinary hatchet excavator except that the
blade is larger, heavier, and is beveled on only one side It has
its cutting edges in a plane that is parallel with the axis of the
handle.
- CUTTING INSTRUMENT APPLICATIONS enamel hatchet It is used for
cutting enamel and comes as right or left types for use on opposite
sides of the preparation.
- CUTTING INSTRUMENT APPLICATIONS gingival margin trimmer Similar
in design to enamel hatchet except the blade is curved. Right and
left types: Right pair is for either a mesial or distal gingival
margins. Left pair is for a mesial or distal margins
- CUTTING INSTRUMENT APPLICATIONS gingival margin trimmer
- CUTTING INSTRUMENT APPLICATIONS gingival margin trimmer When
the second number in the formula is 90-100, it is used for distal
gingival margins. When this number is 75-85, the pair is used to
bevel the mesial margins. 100 and 75 pairs for steep margins for
inlay preparation while 90-85 for slight bevel in amalgam
preparations.
- CUTTING INSTRUMENT APPLICATIONS gingival margin trimmer Uses of
GMT : Beveling of the gingival margins of proximoocclusal
preparations. Beveling of the axiopulpal line angle. 1 2
- CUTTING INSTRUMENT APPLICATIONS gingival margin trimmer
Performing a gingival lock (reverse bevel), placed on the gingival
seat. e.g. GMT 100 for the distal and GMT 75 for the mesial. 3
- cutting instrument sharpening The cutting edge of the hand
instrument should always be kept sharp as dull instruments may
cause: 1. Loss of control. 2. More pain. 3. Prolonged time for the
operative procedure. 4. Reduce the quality and precision of tooth
preparation. Sharpening
- cutting instrument sharpening sharpening equipment Stationary
sharpening stone e.g. Arkansas stone, silicon carbide. 1
- sharpening Mechanical sharpener; moves at low speed while the
instrument is held at the opposite angle and supported by a rest
i.e. easier and less time consuming. 2 Mechanical sharpener
- There are four grasps used with the hand instruments: Modified
pen. Inverted pen. Palm and thumb. Modified palm and thumb. With
each grasp proper rest and guard is important. 1 2 3 4 Instrument
grasp
- 1. Modified pen grasp It is similar to that used in holding a
pen except that the thumb, index and middle fingers contact the
instrument while the tips of the ring and little fingers are placed
on the working tooth as a rest.. The palm of the hand is facing
away from the operator.
- pen grasp Modified pen grasp
- 2. inverted pen grasp If the hand is rotated so that the palm
faces more toward the operator. If is used in the lingual and
labial surfaces of anterior teeth. inverted pen grasp
- 3. Palm and thumb grasp (grasp of power) The handle of the
instrument is placed on the palm of the hand and grasped by all the
fingers while the thumb is free of the instrument and rest on the
nearby tooth of the same arch. Palm and thumb grasp
- 4. Modified palm and thumb grasp The same as in palm and thumb
grasp but the thumb is rested on the tooth being prepared. Used in
the upper arch. Modified palm and thumb grasp
- rests : A proper instrument grasp must include a firm rest
(support) to steady the hand during operative procedures. The
support may be gained from hard tissue. Soft tissue rest or too
distant hard tissue rest does not afford a reliable control.
Instrument rest
- Indirect rest may be gained by using the index finger of the
opposite hand to rest on the shank of the instrument. The operating
hand rests on the opposite hand which rests on stable oral
structures.
- Instrument guards guards : The use of interproximal wedges to
protect soft tissues from contact with sharp rotary cutting
instruments.
- Cleaning and Sterilization Instrument Cleaning and
Sterilization Cleaning and Sterilization
- Cleaning and Sterilization Cleaning All instruments need to be
cleaned and thoroughly dried before they are sterilized. Cleaning
Hand Scrubbing Ultrasonic Cleaning Automated Washer
- 1-Hand Scrubbing Advantages -Effective if performed properly
Disadvantages -Increases chances for operator injury. -Increases
spread of contamination through splatter. -Labor-intensive. -Need
proper care of scrub brush
- 2-Ultrasonic Cleaning Advantages -Safer than hand scrubbing.
-Effectively cleans all instruments . Reduces chances for spread of
contaminants through splatter. -Allows for more efficient use of
staff time Disadvantages -Microorganisms may accumulate in cleaning
solution. -Ultrasonic cleaning will not remove hardened Permanent
cement. (Solution: remove cement while it is still soft.).
- 3-Automated Washer Advantages -Safer than hand scrubbing.
-Reduces chances for spread of contaminants of contaminants through
splatter and aerosols. -Allows for more efficient use of staff
time. -Effectively cleans instruments. Disadvantages -Not all
instruments are compatible with automated washers. -Please see
manufacturer's instructions for detailed requirements.
- Sterilization
- process by which an article, surface or medium is freed of all
living microorganisms.
-
- -Most dental offices have a designated area for instrument
reprocessing that is separate from the dental treatment room. This
is ideal, since cleaning, sterilizing and storing instruments in
the same room where the delivery of patient care is provided
increases the risk of cross-contamination.
- -Some instruments and materials are single use only. -
Single-use items should be segregated in the operatory, and those
that are sharp or otherwise pose a risk of injury must be discarded
into a sharps container . -Items without risk, such as a saliva
ejector, can be thrown into the trash. -To prevent accidental
injury with the contaminated instruments, special handling should
be used to transport the instruments to the cleaning and
sterilization area.
- -Although heavy-duty gloves (utility gloves) may feel more
awkward than examination gloves, they provide extra protection
while handling instruments during the cleaning, rinsing, drying,
packaging and sorting procedures that take place during instrument
reprocessing utility gloves
- Sterilization Steam pressure sterilization ( autoclave) Dry
heat sterilization (dryclave ) Ethylene oxide sterilization
Chemical vapor pressure sterilization (chemiclave)
- 1-Steam preasure strillization (autoclaving) -Sterilization
with steam under pressure is performed in a steam autoclave . -For
a light load of instruments, the time required at 250'F (121 C) is
a minimum of 15 minutes at 15 lbs of pressure. -Time for wrapped
instruments can be reduced to 7 minutes if the temperature is
raised to approximately 273 F (134 C) to give30 pounds of
pressure.
- An example of a steam pressure sterilizer (autoclave)
- Advantages of Autoclaves. -Autoclaving is the most rapid and
effective method for sterilizing cloth surgical packs and towel
packs. -Automated models are available. -although they still can be
misused or fail almost as often as nonautomated ones; they must be
evaluated with a biologic spore test monitoring system.
- Disadvantages of autoclaves -Items sensitive to the elevated
temperature can not be autoclaved. -Autoclaving tends to rust
carbon steel instruments.
- 2-CHEMICAL VAPOR PRESSURE STERILIZATION (CHEMICLAVING )
-Sterilization by chemical vapor under pressure is performed in a
Chemiclave. -Chemical vapor pressure sterilizers operate at 270 F
(131 C) and 20 pounds of pressure. -They are similar to steam
sterilizers and have a cycle time of approximately half an
hour.
- Advantages of Chemiclaves . -Carbon steel and other
corrosion-sensitive burs, instruments, and pliers are said to be
sterilized without rust or corrosion. Disadvantages of Chemiclaves
. - Items sensitive to the elevated temperature will be damaged.
-Instruments must be lightly packaged in bags obtained from the
sterilizer manufacturer. - Towels and heavy cloth wrappings of
surgical instruments may not be penetrated to provide
sterilization. - Routinely use biologic spore test monitoring
strips to confirm heat penetration of heavy packs before use.
- Chemical vapor pressure sterilizer (Chemiclave)
- 3. Dry heat sterilization (dryclave)
- Is an excellent means of sterilization sharp instrument but
rubber and plastic material can not be sterilized by this method
.
- -Dry heat sterilizers for use in dental offices are available,
but all that is necessary is an oven that will maintain a
temperature of 160C(320F)
-It imperative that all debris be removed from an instrument before
it placed in a dry heat sterilizer . * Holding period :
160C(320F),1 hour .
- Advantages of this method 1-is an excellent means of
sterilization sharp instrument. 2-instrument not corrode or rust.
Disadvantages 1-a lower temperature or a shorter period will not
produce the desired result . 2-The higher temperature of a dry-heat
sterilizer means that paper will scorch and plastic will melt.
3-some hand pieces can not be sterilized by this method
- Cox rapid heat transfer dry heat sterilizer
- 4-ETHYLENE OXIDE STERILIZATION - Ethylene oxide sterilization
is the best method for sterilizing complex instruments and delicate
materials. -ethylene oxide gas is toxic for all viruses and
bacteria at room temperature on exposure for 8-10 hr at elevated
temperature . -this method requires rather expensive equipment
.
- Room temperature ethylene oxide sterilizer
- BOILING WATER *Boiling water does not kill spores and cannot
sterilize instruments. However, heat can reach and kill blood borne
pathogens in places that liquid sterilants and disinfectants used
at room temperature cannot reach. *Boiling is a method of
high-level disinfection that has been used when actual
sterilization cannot be achieved (e.g., in case of a sterilizer
breakdown)
- New methods of sterlization **Various new methods of
sterilization are under investigation and development. -The
microwave oven has major limitations for sterilizing metal items,
by either damaging the machine or not reaching all sides of the
instruments. microwave oven
- - Ultraviolet light is not highly effective against RNA viruses
such as HIV and is not very effective against bacterial spores
Ultraviolet light
- -Incomplete exposures of all surfaces and poor penetration of
oil and debris are other limitations. - Ultraviolet irradiation may
be useful for sanitizing room air to help control tuberculosis
bacteria .
- Instrument storage in dental cabinet 1-After the instrument are
sterilized, they are placed in proper place in a dry condition .
2-The portions of dental cabinet designated for hand instrument
contain grooved glass or metal trays. 3-These instrument containers
must be kept in clean and aseptic condition. 4-hey should also
contain protective medium for cutting edges of the instrument
.
- The purpose of this :
- Effects of Sterilization Sterilizing carbon steel instruments
by any of (cold disinfection, boiling water, steam under pressure
(autoclave) causes discoloration, rust, and corrosion.
- minimizing these problems are available.
-
- 1-electroplate the instrument. This affords protection,
except
-
- on the blade, where use and sharpening remove the plating.
-
-
- 2- use of rust inhibitors, which are soluble alkaline
compounds.
-
- 3-is to remove the instruments promptly at the end of the
recommended sterilizing period, dry them thoroughly, and place them
in the instrument cabinet or on the tray setup.
- Non cutting instrument Non cutting instrument Amalgam condenser
Mouth mirror others
- 1. Amalgam condenser It is a dental instrument used for
compacting silver amalgam while in a plastic state, used for
restoring teeth to a natural contour. Condensers come in single-
and double-ended designs. They have various shaped and sized
working ends, which may be smooth or serrated.
- Various Amalgam condensers
- 2. mouth mirror mouth mirror or dentist's mirror is an
instrument used in dentistry. The head of the mirror is usually
round, and the most common sizes used are the No. 4 and No. 5. A
No. 2 is sometimes used when a smaller mirror is needed, such as
when working on back teeth with a dental dam in place.
- its most important functions are:
- allowing indirect vision by the dentist .
- reflecting light onto desired surfaces.
- retraction of soft tissue.
- 4. others A. Carvers. After the amalgam is condensed, it must
then be carved to approximately the same original tooth structure.
Carvers have sharp cutting edges that are used to shape, form, or
cut tooth anatomy into amalgam restorations.
- Carvers
- B. Burnishers. When the carving is complete, the dentist may
use burnishers. used to smooth and polish the restoration. remove
scratches left on the amalgam surface by a carving instrument.
- Burnishers
- C. disposable brush used with etching and bonding procedures
associated with composite resins is a disposable brush with a
reusable handle. aiding in good infection control practices.
Disposable brush and handle.
- Thanks for attention