3Contantes •Cleaning and Sterilization •Non cutting instrument •SharpeningStationary sharpeningMechanical sharpening•IntroductionDefinitionHistory•ClassificationCutting instrumentNon cutting•Instrument graspModified pen. Inverted pen.Palm and thumb.Modified palm and thumb.•Cutting instrumentMATERIALSHardening and TemperingHeat TreatmentsDesignShank anglesNomenclatureFormulaBevels•Cleaning and Sterilization•Non cutting instrumentAmalgam condenserMouth mirrorOthersDesigned by : Ahmed maky•Cutting instrument applicationsExcavatorsChisels
4Introduction Definition : History : 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.Designed by : Ahmed maky
5there 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.Designed by : Ahmed makyDesigns of some early hand instruments
6G.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
8Cutting Instrument remains bright under most conditions. MATERIALSHand cutting instruments are manufactured from two main materials.carbon steelstainless steelremains bright under most conditions.Is harder than stainless steel.Designed by : Ahmed makyloses a keen edge during use much more quickly than does carbon steelwhen unprotected, it willcorrode.
9Tungsten carbide inserts or blades to provide MATERIALSTungsten carbide inserts or blades to providemore durable cutting edges (brittle). They maybe soldered to steel handles.some instruments are made with carbide toprovide more durable cutting edges.
10MATERIALSOther alloys of nickel, cobalt, or chromium are used in the manufacture of hand instruments.Stainless SteelCarbon steel
11Hardening and Tempering Heat Treatments: MATERIALSHardening and Tempering Heat Treatments:To gain maximal benefits from carbon steel or stainless steel, the manufacturer must submit them to two heat treatments: hardening and tempering .Heat treatment Furnace
12Heat treatment relieves strains and increases toughness. the tempering MATERIALSThe 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 temperingHeating or flaming of hand instrumentsduring dental use can alter the originalproperties of the alloy and render itunserviceable.
13a- Blade or nib b-Shank c-Handle DesignMost hand instruments composed of three parts :a- Blade or nibb-Shankc-Handle
14a- blade This is the working part of the instrument. Designa- bladeThis is the working part of the instrument.Begins at the point which terminates theshank.It is connected to the handle by the shank.Each blade has a cutting edge which is theworking part of the instrument.It is usually in the form of a bevel (acuteangle) that cuts into the tooth structure.On non cutting instruments e.g. condensersthe part corresponding to the blade is called the nib or face.
15b-shank Connect the handle to the working end of the instrument. Designb-shankConnect the handle to the working end of the instrument.Normally smooth, round and tapered.Have one or more angles to avoid twisting ofthe instrument.Hand instruments must be balanced and sharp.Balance allows for the concentration offorce onto the blade without causingrotation of the instrument.
16Shank angles: Balance is accomplished by designing the angle of the shank so that the cutting edgeof the blade must not be off axis by morethan 1-2 mm.Shank angles:Mon-angle, bin-angle, triple angle.Instruments with small short blades may bemonangle
17Instruments with long blades may required DesignInstruments with long blades may requiredtwo or three angles in the shank to bring thecutting edge near to the long axis of thehandle.Such shanks are termed contra angled.
18c- handle(shaft) It is the part grasped in the operator’s hand. Designc- handle(shaft)It is the part grasped in the operator’s hand.Perfectly straight, smooth or eight sided.Serrated for better gripping and control of theinstrument.Handles are in conjunction with the shank orit may be separable.Separate type is known as cone-sockethandle and allows for replacement of severalworking ends e.g. mirrors and condensers.
20Black classified all instruments by name according to: nomenclatureBlack 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. spoonexcavator, sickle scaler4. Shape of the shank e.g. mono-angle, biangle, contra-angle.•These names were combined to form thecomplete description of the instrument e.g.binangle spoon excavator.
21Hand cutting instruments have formulas describing the dimensions and angle ofthe working end.These are placed on the handle using acode of three or four numbers separatedby dashes or spaces (e.g ).The first number indicatesthe width of the blade intenths of a mm (e.g. 10 = 1 mm).The second number primary cutting edge anglemeasured from a line parallel to the long axis ofthe handle in clockwise centigrade.
22blade design with formula. Instrument shank andblade design with formula.
23If the edge is perpendicular to the blade, formulaIf the edge is perpendicular to the blade,this number is omitted resulting in a 3numbers code.The third number indicates the bladelength in mm (e.g. 8 = 8 mm).The fourth number indicates the blade angle relative to thelong axis of the handle in clockwise centigrade e.g. (14)Additional number on the handle is the manufacturer’s identification number.
24Additional number should not be confused with the formula number.
25Additional two secondary cutting edges that BevelsMost hand cutting instruments have on the end of the blade a single bevel that forms the primary cutting edge. Two additional edges,Additional two secondary cutting edges thatextend from the primary cutting edge for thelength of the blade.This allows cutting in 3 directions; facial andlingual walls of the proximal cavity.Chisel blade design showing primary and secondary cutting edges.
26Bibeveled instrument have two bevels that form the cutting edge, e.g. hatched excavator.
27Single beveled instrument such as spoon excavator and gingival BevelsSingle beveledinstrument such asspoon excavatorand gingivalmargin trimmer areused with lateralcutting movement.
28planning or lateral cutting designated for right and left to BevelsEnamel hatchet also as a single beveled instrument used with direct cutting motion, aplanning or lateral cuttingdesignated for right and left tothe instrument formula.
29The opposite is true for the left instrument of the pair. BevelsRight and left bevelsTo 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.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.
30The cutting edge is perpendicular to the axis of the handle BevelsThe cutting edge is perpendicular to the axis of the handlee.g. binangle chisel.Instrument with slight blade curvature e.g.Wedelstaedt chisel.
31Cutting instrument applications Applications can be classified into:written and designed by - Ahmed Maky-Removal of caries and refinement of the internal parts of the preparation.-Used primarily for cutting enamel.
32CUTTING INSTRUMENT APPLICATIONS written and designed by - Ahmed Maky
33CUTTING INSTRUMENT APPLICATIONS Hatchet excavatorIt has the cutting edge of the blade directed in the same plane as that of the long axis of the handle and is bibeveled .written and designed by - Ahmed Maky
34CUTTING INSTRUMENT APPLICATIONS Hatchet excavatorThese instruments are used primarily on anterior teeth for preparing retentive areas and sharpening internal line angles, particularly in preparations for direct gold restorations .written and designed by - Ahmed Maky
35CUTTING INSTRUMENT APPLICATIONS Hoe excavatorIT has the primary cutting edge of the blade perpendicular to the axis of the handlewritten and designed by - Ahmed Maky
36CUTTING INSTRUMENT APPLICATIONS Hoe excavatorThis 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.written and designed by - Ahmed Maky
37CUTTING INSTRUMENT APPLICATIONS Hoe excavatorSome 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.written and designed by - Ahmed Maky
38CUTTING 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 )written and designed by - Ahmed Maky
39CUTTING 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 marginswritten and designed by - Ahmed Maky
40CUTTING INSTRUMENT APPLICATIONS - the cutting edges are circular. Spoon excavatorIts blades are slightly curved, the shanks may be bin-angled or triple-angled to facilitate accessibility.written and designed by - Ahmed Maky- the cutting edges are circular.-the cutting edges are claw like.
41CUTTING INSTRUMENT APPLICATIONS bin-angled spoonwritten and designed by - Ahmed Makytriple-angled spoon
42CUTTING INSTRUMENT APPLICATIONS written and designed by - Ahmed MakyCleoid spoon
43CUTTING INSTRUMENT APPLICATIONS written and designed by - Ahmed MakyDiscoid spoon
44CUTTING INSTRUMENT APPLICATIONS written and designed by - Ahmed Maky
45CUTTING INSTRUMENT APPLICATIONS straight, slightlycurved, or bin-angleThe 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.written and designed by - Ahmed Maky
46CUTTING INSTRUMENT APPLICATIONS straight, slightlycurved, or bin-angleThe shank and blade of the chisel also may be slightly curved (Wedelstaedt design)written and designed by - Ahmed Maky
47CUTTING INSTRUMENT APPLICATIONS straight, slightlycurved, or bin-angleThe shank and blade of the chisel also may be bin-angled .written and designed by - Ahmed Maky
48CUTTING INSTRUMENT APPLICATIONS straight, slightlycurved, or bin-angleThe 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.written and designed by - Ahmed Maky
49CUTTING INSTRUMENT APPLICATIONS straight, slightlycurved, or bin-angleThe bin-angle and Wedelstaedt chisels havethe 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.written and designed by - Ahmed Maky
50CUTTING INSTRUMENT APPLICATIONS straight, slightlycurved, or bin-angleThe blade with a distal bevel is designed to plane a wall that faces the blade's inside surfacewritten and designed by - Ahmed Maky
51CUTTING INSTRUMENT APPLICATIONS The blade with a mesial bevel is designed to plane a wall that faces the blade's outside surfacewritten and designed by - Ahmed Maky
52CUTTING INSTRUMENT APPLICATIONS enamel hatchetIt is a chisel similar in design to the ordinary hatchet excavator except that the blade is larger, heavier, and is beveled on only one sideIt has its cutting edges in a plane that is parallel with the axis of thehandle.written and designed by - Ahmed Maky
53CUTTING INSTRUMENT APPLICATIONS enamel hatchetIt is used for cutting enamel and comes as right or left types for use on opposite sides of the preparation.written and designed by - Ahmed Maky
54CUTTING INSTRUMENT APPLICATIONS gingival margin trimmerSimilar in design to enamel hatchet except the blade is curved.Right and left types:Right pair is for either a mesial or distalgingival margins.written and designed by - Ahmed MakyLeft pair is for a mesial or distal margins
55CUTTING INSTRUMENT APPLICATIONS gingival margin trimmerwritten and designed by - Ahmed Maky
56CUTTING INSTRUMENT APPLICATIONS gingival margin trimmerWhen the second number in the formula is , it is used for distal gingival margins.When this number is 75-85, the pair is usedto bevel the mesial margins.100 and 75 pairs for steep margins for inlaypreparation while for slight bevel inamalgam preparations.written and designed by - Ahmed Maky
57CUTTING INSTRUMENT APPLICATIONS gingival margin trimmerUses of GMT :Beveling of the gingival margins of proximoocclusal preparations.Beveling of the axiopulpal line angle.1written and designed by - Ahmed Maky2
58CUTTING INSTRUMENT APPLICATIONS gingival margin trimmerPerforming a gingival lock (reverse bevel), placed on the gingival seat.e.g. GMT 100 for the distal and GMT 75 for the mesial.3written and designed by - Ahmed Maky
59Sharpeningcutting instrumentsharpeningThe cutting edge of the hand instrument should always be kept sharp as dullinstruments may cause:1. Loss of control.2. More pain.3. Prolonged time for the operative procedure.4. Reduce the quality and precision of toothpreparation.
60cutting instrumentsharpeningsharpening equipment1Stationary sharpening stone e.g. Arkansas stone, silicon carbide.
612 Mechanical sharpener; moves at low sharpening2Mechanical sharpener; moves at lowspeed while the instrument is held at theopposite angle and supported by a resti.e. easier and less time consuming.Mechanical sharpener
62Instrument grasp 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 isimportant.1234
631. Modified pen graspIt is similar to that used in holding a pen exceptthat the thumb, index and middle fingers contactthe instrument while the tips of the ring and littlefingers are placed on the working tooth as a rest..The palm of the hand is facing away from theoperator.
652. inverted pen grasp inverted pen grasp If the hand is rotated so that the palmfaces more toward the operator.If is used in the lingual and labial surfacesof anterior teeth.inverted pen grasp
663. Palm and thumb grasp (grasp of power) The handle of the instrument is placed on the palm of the hand and grasped by all thefingers while the thumb is free of theinstrument and rest on the nearby tooth of the same arch.Palm and thumb grasp
674. Modified palm and thumb grasp 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
68Instrument rest rests : A proper instrument grasp must include a firm rest (support) to steady the hand duringoperative procedures.The support may be gained from hard tissue.Soft tissue rest or too distant hard tissue restdoes not afford a reliable control.
69Indirect rest may be gained by using the index finger of the opposite hand to reston the shank of the instrument.The operating hand rests on the oppositehand which rests on stable oral structures.
70Instrument guardsguards :The use of interproximal wedges to protect soft tissues from contact with sharp rotary cutting instruments.
71Cleaning and Sterilization Cleaning and Sterilization Instrument Cleaning and Sterilization
72Cleaning and Sterilization All instruments need to be cleaned and thoroughlydried before they are sterilized.
731-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
742-Ultrasonic CleaningAdvantages-Safer than hand scrubbing.-Effectively cleans all instruments .Reduces chances for spread ofcontaminants through splatter.-Allows for more efficient use of staff timeDisadvantages-Microorganisms may accumulate in cleaning solution.-Ultrasonic cleaning will not remove hardened Permanent cement. (Solution: remove cement while it is still soft.).
753-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.
76Sterilizationprocess 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.
77-Some instruments and materials are single use only.- Single-use items should besegregated in the operatory,and those that are sharpor otherwise pose a risk of injurymust be discarded into a sharps container .-Items without risk, such asa 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.
78-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 reprocessingutility gloves
801-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 israised to approximately 273° F (134° C) to give30 pounds of pressure.
81An example of a steam pressure sterilizer (autoclave)
82Advantages of Autoclaves. -Autoclaving is the most rapid and effective method forsterilizing 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 evaluatedwith a biologic spore test monitoring system.
83Disadvantages of autoclaves -Items sensitive to the elevated temperature can not be autoclaved.-Autoclaving tends to rust carbon steel instruments.
842-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.
85Advantages 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.
873. 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 160°C(320°F)-It imperative that all debris be removed from an instrument before it placed in a dry heat sterilizer .*Holding period : 160°C(320°F),1 hour .
88Advantages of this method 1-is an excellent means of sterilization sharp instrument.2-instrument not corrode or rust.Disadvantages1-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
904-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 hr at elevated temperature .-this method requires rather expensive equipment .
92BOILING WATER*Boiling water does not kill spores and cannot sterilizeinstruments. 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)
93New 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
94-Ultraviolet light is not highly effective against RNA viruses such as HIV and is not very effective against bacterial sporesUltraviolet light
95-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 .
96Instrument 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 forcutting edges of the instrument .
98Effects 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, excepton the blade, where use and sharpening remove the plating.
992- 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.
1011. Amalgam condenserIt 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.
1032. mouth mirror its most important functions are: 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.
1064. othersA. 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.
110Disposable brush and handle. C. disposable brushused 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.