1. HAND INSTRUMENTS IN OPERATIVE DENTISTRY By:- Dr Abhijeet D Khade Nair Hospital Dental College, Mumbai

2. Contents:- Introduction History Materials used Heat treatment Classification Nomenclature Instrument formula Instrument parts Measuring gauzes Types of hand cutting instruments Hand instrument technique Sharpening hand instruments Sterilization and disinfection Summary and conclusion References

4. The purpose of the instrument.

5. The position or manner of use.

7. These instruments had bone or ivory handles (effective sterilization was not possible).

8. There was no uniformity of manufacture and nomenclature.

9. Many dentists made their own hand instruments in an effort to find a suitable instrument for specific need.

10. Early hand instruments were grasped in the palm of the hand.

11. As cavity preparations refined and the access to various surfaces of teeth desired:- - Grasp changed to pen grasp. - Instrument with large, straight blades modified to smaller, angled blades.

12. Dr. G.V. Black - Credited with the first acceptable nomenclature for and classification of hand instruments. Dr. Arthur D. Black - Developed many of the instruments and techniques. Dr. Charles E. Wood Bury - First to modify blacks instrumentation. Designed 39 sets of Hand instruments for Class III cavity preparations & condensing points for building gold foil restorations. Dr. Wedelstaedt- Developed Wedelstaedt chisel now referred to as “Curved Chisel”. Dr. Waldon I. Ferrier – Developed a new set of instruments called ferrier set which were more refined and had uniform thickness on the cutting edge. Dr. George Hollenback – Invented pneumaticcondenser.

13. MATERIALSUSED Hand cutting instruments are manufactured from two main materials: Stainless steel Carbon steel Some instruments are made with carbide inserts to provide more durable cutting edge. - Hard and wear resistant but is brittle too.

14. Stainless steel Chromium 18% Carbon 1% Iron 81- 81.4% Adv.:- - Chromium in the alloy reduces the corrosion tendency by depositing an oxide layer on the surface of the metal. - Remains bright under most conditions. Disadv:- - Maintaining the sharpness of the blade is a problem. - Loses a keen edge during much use. Mainly used for working points and cement instruments. Carbon steel Carbon 1 – 1.2% Manganese 0.2% Silicon 0.2% Iron 98.4 – 98.6% Adv.:- - Harder than stainless steel. Disadv:- - When unprotected, it will corrode. Stellite Cobalt 65 – 90% Chromium 35% Trace amounts : tungsten, molybdenum and iron. Adv.:- - High resistance to acid - Hardness Use: Manufacture of mixing and inserting instruments.

15. Other alloys: Alloys of nickel, cobalt or chromium are used in the manufacture of hand instruments.

16. MANUFACTURINGPROCESS Blank steel is bent to the degree of angulation needed in the shank and blade. The edges are milled to produce the cutting edge and structural design. Martensitic type of stainless steel is used for manufacturing cutting instruments (high strength and hardness).

19. Non-cutting (Amalgam condensers, mirrors, explorers, probes)

21. II. ACCORDING TO CHARBENAU 2. Condensing Instruments Pluggers - Hand - Mechanical 3. Plastic Instruments - Spatulas - Carvers - Burnishers - Packing Instruments 1. Cutting instruments Hand - Hatchets - Chisel - Hoe - Excavator - Others Rotary - Burs - Stones - Disk - Others

22. 4. Finishing and Polishing Instruments Hand - Orange wood sticks - Polishing points - Finishing strips Rotary - Finishing burs - Mounted brushes - Mounted stones - Rubber cups - Impregnated disk and wheels 5.Isolation Instruments - Rubber dam frame Clamps Forceps Punch - Saliva ejectors - Cotton roll holders - Evacuating tip and equipments 6. Miscellaneous Instruments - Mouth Mirrors - Probe - Scissors - Pliers - Others

23. III. ACCORDING TO MARZOUK: 1. Exploring or diagnostic instruments: - Mouth mirror - Explorer or probe - Straight probe - Right angled probe - Arch shaped (Shepherds hook) - Interproximal (Back action) - Tweezers - Seperators - Cheek retractors - Air syringe 2. Isolating instruments: - Cotton roll holder - Rubber dam - Saliva ejector - Suction apparatus 3. Hand cutting instruments: - Excavators - Spoon excavator - Cleiod - Discoid - Hatchet excavator - Hoe - Chisels - Straight chisel - Mono angle chisel - Bin angle chisel - Triple angle chisel - Special types of chisels or modified chisels - Wedelsteadt chisel - Enamel hatchet - Gingival marginal trimmer - Angle former

24. 4. Restoring instruments: - Mixing instruments - Cement spatula - Agate spatula - Plastic carrying/ filling instruments - Packing instruments - Amalgam carrier - Condensing instruments - Round condenser - Parallelogram condenser - Burnishing instruments - Ball shaped - Egg shaped - Conical shaped - Carving instruments - Hollenback carver - Diamond carver - Wards carver 5. Miscellaneous instruments: - Matrices and retainers - Scissors

25. NOMENCLATURE In establishing a nomenclature for hand instruments, Dr G.V. Black prescribed four classes similar to biological classification: ORDER: Purpose of the instruments SUBORDER: Position or manner of use CLASS: Form of working end SUB CLASS: Shape of the shank Bin-anglehatchetpushexcavator.

26. PARTSOFHANDINSTRUMENTS Handle/ Shaft Shank Blade with cutting edge or Nib with face.

28. Instrument formula incorporated on it.

29. Manufacturing kit number incorporated on it.

31. CONTRA ANGLE AND BALANCE The term “Contra – Angle” refers to a shank in which two or more angles are necessary to bring the working end into near alignment with (within 2-3mm) the axis of the handle. Advantages: - Prevent rotation - Modified access - Greater stability and balance - Ease of control.

32. BLADE Functional end of the instrument that bears the cutting edge. It is connected to the handle by the shank. For non-cutting instruments, the part corresponding to the blade is termed “Nib”. Working surface or the end of the nib is known as the “face”.

34. DIRECT CUTTING Force is applied in the same plane as that of the blade and handle Straight blade (single plane). All the curves and the angles in the shank are in the same plane as the handle. Used in direct & lateral cutting. LATERAL CUTTING Force is applied at a right angle to the plane of the blade and the handle Curved blade (double plane). Angles or curves in a plane at a right angle to the handle. Can only be used in lateral cutting (scraping action).

35. INSTRUMENTFORMULA GIVEN BY G.V.BLACK: 3 unit instrument formula: Cutting edge of the instrument is at a right angle to the blade. a. First unit – Width of the blade in tenths of a millimeter. b. Second unit – Length of the blade in millimeter. c. Third unit – Angle the blade forms with the axis of the handle in centigrade. Instrument formula of enamel hatchet.

36. 4 unit instrument formula: Cutting edge of the instrument is at an angle other than a right angle to the blade. a. First unit – Width of the blade in tenths of a millimeter. b. Second unit - Angle the cutting edge forms with the axis of the handle in centigrade. c. Third unit – Length of the blade in millimeter. d. Fourth unit – Angle the blade forms with the axis of the handle in centigrade. Example:- Gingival marginal trimmer & angle former. Instrument formula of distal GMT

37. MEASURING GAUZES BOLEY’S GAUZE CENTIGRADE SCALE

38. MEASURING ANGLE OF THE BLADE AND CUTTING EDGE

39. Types of hand cutting instruments Chisels:- - Cutting edge of the instrument is at a right angle to the axis of the instrument. - Used for planing or cleaving enamel. 1) Straight chisel:- - No bend in shank - Single beveled/ Triple beveled. - Minimal accessibility. - Used with push stroke or lateral scraping action.

40. 2) Mono angle chisel:- - Blade is shorter as compared to straight chisel. - Single angle in the shank to enhance the convenience form. - Used with push stroke or lateral scraping action. Hoe:- Difference between mono angle chisel and hoe:- - If the angle of the blade is less than 12.5 centigrade, it is mono angle chisel and if it is more than 12.5 centigrade, it is hoe. - Used with pull stroke. Use:- To define line and point angles. - Class III and V preparations for direct filling gold restorations.

41. 3) Binangle chisel:- - Two angles in the shank. - Used to cleave or split undermined enamel. - Reverse bevel instrument. 4) Triple angle chisel:- - Used to flatten the pulpal floor.

42. Hatchet:- - Cutting edge of the instrument is parallel to the axis of the instrument. - Cutting edge of the instrument is at right angle to the axis of blade. - Mono angled - Length of blade is very small - Bibevelled - Single ended - Used with push stroke Use:- - Preparing retentive areas on anterior teeth. - Sharpening internal line angles in DFG restorations.

43. Enamel hatchet:- - Cutting edge of the instrument is parallel to the axis of the instrument. - Cutting edge of the instrument is at right angle to the axis of blade. - Binangle hatchet - Monobeveled - Single plane instrument - Paired instrument - Bevel on right side – Right side instrument - Bevel on left side – Left side instrument

44. Used with push stroke (planing or direct cutting motion as well as lateral cutting motion). Used for smoothening buccal and lingual walls of proximal box. Used for breaking enamel of proximal box. Used for smoothening gingival seat (lateral scraping motion).

45. Gingival marginal trimmer:- - Cutting edge of the instrument is parallel to the axis of the instrument. - Cutting edge of the instrument is at an angle other than a right angle to the blade. - Modified hatchet - Binangle instrument - Monobeveled - Double plane instrument (better lateral scraping efficiency/ scooping effect).

46. MESIAL PAIR (RIGHT AND LEFT) - 2 pairs - 4 unit instrument formula - Mesial pair – 10- 80- 6- 8 ( < 80 ) - Distal pair – 10- 95- 6- 8 ( > 95) - Used to give gingival cavo surface bevel. - Used for rounding or bevellingaxio- pulpal line angle. DISTAL PAIR (RIGHT AND LEFT) GMT USED IN HORIZONTAL AND VERTICAL STROKES

47. Angle former:- - The instruments are made by grinding the bevel at an angle of 800 with the shaft, thus forming an acute angle with the long axis of the blade. This creates a pointed and a linear cutting edge. - 4 unit instrument formula - Paired instrument- right and left - Ring on the shank – right side - 3 cutting edges (blade is beveled on the sides as well as the end). Use:-To exaggerate line and point angles in DFG restorations to establish the retention form. ANGLE FORMERS (LEFT AND RIGHT)

48. Wedelstaedt chisel:- - Shank and blade are curved. - Beveled on one side of blade only. - If bevel is on the side towards the curvature of the shank:- Mesially beveled. - Away from the curvature of the shank:- Distally beveled - Used for cleaving undermined enamel and for shaping walls. - Single instrument with 3 cutting motion:- vertical, right and left.

50. Spoon excavator:- - Modified hatchet. - Double ended instrument. - Binangle/ Triple-angle instrument. - Paired (right and left). - Double plane instrument. - Circumferentially beveled. - Cutting edge either circular (discoid) or claw like (cleoid). Use:- Spooning or scooping of softened carious material. - Carving amalgam or direct wax patterns. DIFFERENT SPOON EXCAVATORS

51. Other instruments:- Knives:- Finishing knives, Amalgam knives, or Gold knives. Used for trimming excess restorative material on the gingival, facial or lingual margins of a proximal restoration or trimming and contouring the surface of class V restorations. Files:- Used for smoothening of overhanging restorations (amalgam and gold).

52. Non cutting instruments Diagnostic instruments:- Mouth mirror:- - Is an instrument having a mirror head top and a detachable handle. - Also called as odontoscope. Types:- A) Front surface:- - Is one where the reflecting surface is on the top of the glass piece. - Gives better visibility. - Absence of intervening glass. - No double image. - Mercury coating on top is liker to be lost due to scratching. B) Rear surface (regular) - Reflecting surface is on the back surface of the mirror lens. - Surface is less easily scratched. - Produces a double or ghost image.

53. C) Magnifying mirror (concave):- - Reflecting surface is on the front surface of the mirror lens. - Produces magnified but slightly distorted image. - Concave surface mirror magnifies the image, requiring the clinician to learn to accommodate movement. - Concave mirror rarely used except for seeing enlarged internal details of the cavity. - The instrument movements are smaller than the clinician visual perception. - For endodontic surgeries. D) Disposable mirror:- - Made of plastic.

54. Uses:- Indirect illumination. - Mouth mirror could be held at an angle to reflect the light onto the working area. Retraction - Mirror head used to retract the patient’s lip or check or tongue so that the clinician is able to view tooth surfaces. Protects from injury. Indirect vision. Guard. Trans illumination. - Only maxillary and mandibular anterior teeth can be trans illuminated. Different sizes of mouth mirror:- No. 2 (5/8 inch) No. 4 (7/8 inch) No. 5 (15/16 inch)

55. DIFRFERENT SIZES NO. 2,4,5. FRONT SURFACE AND REAR SURFACE MIRROR

56. 2) Probe:- - Sharp pointed hand instrument used to explore teeth and restoration surfaces in order to detect caries, overhanging edges and other defects. - May be single-ended or double-ended. Uses:- - Exploring lesion - For detecting and assessing carious lesion in the tooth - Detecting demineralized dentin. - Releasing debris from the tooth. - Removing slight excess fill up around cavo-surface margins - Identifying hypersensitive areas in the tooth - Assessing marginal fit of the restoration

57. Types:- - Straight. - Interproximal probe - No.2 cow horn (arch explorer) - No.17 back action - No. 23 shepherd’s hook - Orban –type explorer Different types of explorers

58. 3) Periodontal probe:- - Detect and measure the depth of periodontal pockets. - In operative dentistry:- Used to determine the dimensions of instruments and of various features of preparations or restorations.

59. 4) Forceps:- - Tweezers/ Cotton forceps - Hemostats - Articulating paper forceps Tweezers:- - Hand instrument with two narrow and pointed, straight or curved beaks used to grasp small objects. Consist of:- - 2 long arms. - Locking device. - 2 long arms joined at one end. - Other end remains apart.

60. Uses: - Useful in carrying things to and from mouth. - Carrying cotton rolls, cotton pledges, sponge pellets to and around the cavity. - Carrying saliva soaked cotton rolls from the oral cavity to the waste disposal unit. Locking tweezer - May have a locking device to maintain the beaks in a closed position until released. - This avoids the unnecessary anxiety of the operator at the possibility of slippage whatever is carried by the tweezer.

61. TWEEZERS ARTICULATING PAPER FORCEPS HEMOSTATS

62. Restoring instruments:- Mixing instruments:- Cement spatula Agate spatula Spatulas:- - Flat and wide nibs with blunt edges. - Shank straight. - Different sizes and different degrees of stiffness in their nibs to suit their various uses. Made of Stainless steel. Plastic. - Doubles ended instrument. Blunt end – for manipulating impression materials. Sharp end - for mixing cements. - Used for manual mixing of cements supplied as powder and liquid.

63. 2) Plastic carrying/ filling instruments:- It is an instrument used for carrying the mixed base cements which are in soft (plastic) stage or the restorative cement from a cement spatula to the cavity. Usually one end is flat and other end is cylindrical. Flat end is used for carrying the cement. Cylindrical end is used for manipulating and positioning the cement. Made of: - Stainless steel - Plastic Also can be plated with teflon to minimize material adhesion.

64. STAINLESS STEEL “PLASTIC” INSTRUMENTS TITANIUM NITRIDE INSTRUMENTS FOR PLACING AND SHAPING COMPOSITE

65. 3) Packing instrument:- Amalgam carrier:- Amalgam carrier is a stainless steel instrument used for carrying mixed amalgam to the cavity. Use:- -Hollow tip of an amalgam carrier is inserted into the mixed amalgam to pack the carrier with amalgam. -It is then carried into the cavity and plunger is pressed injecting cylindrical pellets of amalgam.

66. 4) Condensing instruments. - To pack material into prepared cavity. - Types: A) Amalgam condenser - Hand - Mechanical – Vibratory and Impact type B) Gold condenser - Hand - Mechanical. Hand condenser:- - Are double-ended instruments with the nibs (condensing tips) coming in different size and shapes. - Force varies inversely with the area of the face.

67. Nibs may be:- I) Of different shapes:- Round Elliptical Diamond Triangular Parallelogram Rectangular II) Sizes vary considerably; Large round condenser Small round condenser III) Depending on working end; (condenser face). Serrated – For spherical amalgam Non-serrated (smooth) – For admixed amalgam DIFFERENT TYPES OF AMALGAM CONDENSERS

72. Pen grasp:- - Instrument is held between thumb and first finger with middle finger below acting as a support. - Either the third or third and fourth fingers are placed on adjoining tooth as rest. - Position of middle finger is important – 1) For obtaining thrust 2) Preventing the instrument from slippage during manipulation. - It involves wrist movement. Adv:- -More flexibility of movement. -Less power. -Greatest versatility of movement. -More comfortable. -Limits application of pressure. Disadv:- Bracing is difficult because only the ring and little fingers are used.

73. Modified pen grasp:- - Permits greatest delicacy of touch. - Pads of thumb, index and middle finger contact the instrument, while the tip of the ring finger (or tips of the ring and little fingers) is placed on a nearby tooth surface of the same arch as a rest. - The pad of the middle finger is placed near the “topside” of the instrument for good control and cutting pressure. - The fingers and the thumb engage the instrument as a grappling hook. - The base of the index finger and the tip of the middle finger reciprocate, with the thumb placed midway between them. - The palm of the hand generally faces away from the operator. - Involves forearm which turns inward (pronates) or outward (supinates).

75. Palm and thumb grasp:- - The handle of the instrument is held between the palm and four fingers firmly with the tip of the thumb acting like a rest. - Power grasp. Adv:- - More control and precision. - Limited movement. - Enhance bracing (a forward thrust with the arm of wrist can be controlled by the opposing action from the thumb, which is braced against the teeth). - Gives the possibility of applying pressure precisely. Example: holding a hand piece for cutting incisal retention for Class III preparation on maxillary incisor.

76. Modified palm and thumb grasp:- - The handle of the instrument is held by all four fingers whose pads press the handles against the distal area of the palm, as well as the pad and first joint of the thumb. - The rest is tip of thumb on tooth being prepared or adjacent teeth. Adv:- - Most valuable aid in operating inside and outside the mouth. - Allows greater ease of instrument movement. - More control against slippage during thrust stroke compared to palm and thumb grasp. - Grasping the handle under the first joint of the ring and little finger acts as a stabilizer. - More delicate manipulation.

77. PALM & THUMB GRASP MODIFIED PEN GRASP PEN GRASP

78. INVERTED PEN GRASP PEN GRASP AND MODIFIED PEN GRASP MODIFIED PALM AND THUMB GRASP PALM AND THUMB GRASP

79. Rest:- Is to stabilize the hand and instrument by providing a firm fulcrum as movement are made to activate the instrument. Is required for steady hand during operative procedures. Adv:- A good finger rest prevents injury and laceration of the gingiva and surrounding tissues. The ring finger is preferred as finger rest.

80. When modified pen and inverted pen grasps are used, rests are established by placing the ring or ring and little fingers on a tooth (or teeth) of the same arch and as close to the operating site as possible (more reliable). In palm and thumb grasp, rests are created by placing the tip of the thumb on tooth being operated on, or on an adjacent tooth, or on a convenient area of the same arch. When it is impossible to establish a rest on tooth structure, soft tissue must be used (not reliable).

81. Finger rests classified Intra oral finger rest Extra oral fulcrum Intra oral finger rest:- 1. Conventional Finger rest is established on the tooth surfaces immediately adjacent to the working area. 2. Cross- arch Finger rest is established on the tooth surfaces on the other side of the same arch. 3. Opposite-arch Finger rest is established on tooth surfaces on the opposite arch (e. g:- mandibular arch finger rest for instrumentation on the maxillary arch). 4. Finger – on – finger. Finger rest is established on the index finger or thumb of the non operating hand.

82. Extra oral fulcrums. Two most commonly used- (1) Palm-up. Palm-up fulcrum is established by resting the backs of the middle and ring fingers on the skin overlying the lateral aspect of the mandible on the right side of the face. (2) Palm-down Palm- down fulcrum is established by resting the front surfaces of the middle and ring fingers on the skin overlying lateral aspect of the mandible on the left side of the face.

86. VARIOUS TYPES OF SHARPENING EQUIPMENTS STATIONARY STONES/ OIL STONES - Arkansas stone - Silicon carbide - Aluminium oxide - Diamond MECHANICAL SHARPENERS Rotary (Hand piece) Honing machine

87. Stationary stones/ oil stones - Available in variety of grits, shapes and materials. Grit – Coarse Medium Fine Shapes – Flat – sharpening instruments with straight cutting edges. Grooved – curved edges. Cylindrical – concave edges. Tapered – using portion of the stone with a curvature matching that of the instrument. Initial reshaping of badly damaged instrument Final sharpening

88. Arkansas stone:- - Naturally occuring mineral containing micro crystalline quartz. - Used in fine sharpening stones. - Semi transparent, white or grey in color. - Hard enough to sharpen steel but not carbide instruments. - Should be lubricated with machine oil which helps in fineness of sharpening and prevents clogging avoids creation of heat.

90. Diamond:- - Hardest available abrasive. - Effective for cutting and shaping hard materials. - Used in sharpening carbide and steel instruments. - Diamond hones are small blocks of metal with fine diamond particles impregnated in the surface.

92. PRINCIPLES OF SHARPENING Sharpen the instrument only after they are cleaned and sterilized. Establish the proper bevel angle (450) and desired angle of the cutting edge to the blade before placing the instrument. Maintain these angles while sharpening. Use light strokes or pressure against the stone to minimize frictional heat. Use a rest or guard. Remove as little metal from the blade as possible. Lightly hone the unbevelled side of the blade after sharpening, to remove the fine bur that may be created. After sharpening, resterilize. keep the sharpening stones clean and free of metal cuttings.

93. Sharpness test:- - Tested by lightly resting the cutting edge on a hard plastic surface, such as the handle of a plastic mouth mirror or an evacuator tip. - A dull blade will slide across the plastic; a sharp blade will cut into the surface, stopping movement. - A specially made, sterilizable, sharpness- testing stick is also available (Dalron Test stick, Thompson Dental).

94. Advantages of sharp instrument. - Few strokes - Less effort. - Increase tactile sensitivity and operator control. - Prevent gouging of the root surfaces.

95. STERILIZATION AND DISINFECTION Sterilization: Destruction of both the vegetative form and bacterial spores. Disinfection: Destruction of only vegetative form. Procedures involved in instrument processing: 1) Presoaking 2) Cleaning 3) Corrosion control and lubrication 4) Packaging 5) Sterilization 6) Sterilization monitoring 7) Drying or cooling 8) Storage 9) Distribution 10) Sharpening

98. Steam pressure sterilization (autoclave) Time required 15 min time at 2500F (1210C) and 15 lbs of pressure (light load of instruments) Wrapped instruments – 7 min, 2730F (1340C) at 30 pounds of pressure. Preformed in a steam auto clave. Advantages - Most rapid and effective method for sterilizing cloth surgical packs and towel packs. Disadvantages - Items sensitive to elevated temperature cannot be auto claved. - Tends to rust carbon steel instruments and burs. - Burs can be protected by submerging in anticorrosive agent- 2% sodium nitrite.

99. Chemical vapor sterilization (chemiclave) - Performed in a chemiclave - Operate at 2700F (1310C) at 20 lbs for half an hour. Advantages: - Carbon steel and burs are said to be sterilized without rust. Disadvantages: - Items sensitive to elevated temperature will be damaged. - Towels and heavy cloth wrapping may not be penetrated to provide adequate sterilization. - Only dry instruments should be loaded.

100. Dry heat sterilizaton Conventional dry heat oven:- - Heated at 320oF (1600C) for 30 min. Instruments should be packaged in foil wrap or nylon bags. - Wrapped instruments – 3350- 3450 F for 60-90 mins. Short cycle high temperature dry heat oven:- Sterilization time reduced - 6 min for unwrapped. - 12 min for wrapped. - Temperature – 370 – 3750F.

101. Advantages:- - Carbon steel instruments and burs do not rust, corrode or lose their temper or cutting edge if they are dried before processing. Disadvantages:- - Damage heat sensitive items such as rubber or plastic goods. - Inaccurate calibration, lack of attention to proper setting and adding instrument without restarting the timing are common source of error.

103. 6) Sterilization monitoring: - Sterilization indicator on instrument bag - Daily color change process indicator strip - Weekly biologic spore test - Documentation note book 7) Storage: - In a sterile, wrapped tray set up or in an individual sterile wrapping.