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Operative hand instruments - DR SNEHA


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seminar on hand instruments

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Operative hand instruments - DR SNEHA

  2. 2. Contents • Introduction, history & classification • Parts of a hand cutting instrument • Instrument nomenclature • Instrument formula • Instrument design • Instrument applications • Techniques • Rests and guards • Sharpening hand instruments • Sterilization and disinfection • Conclusion • References
  3. 3. I INTRODUCTION  In order to perform the intricate or detailed procedures associated with operative dentistry, the dentist must have a complete knowledge of the purpose and application of the many instruments required. Theinstruments available Thepurposeof the instrument Theposition or manner of use Theapplication ofthe instrument.
  4. 4. DEFINITION  . The term instrument refers to a tool, device or implement used for specific purpose or type of work and is preferred in professional or scientific fields as precision items generally required to perform specific procedures. -2nd edition M.A. Marzouk
  5. 5. HISTORY
  6. 6. HISTORY EARLY HAND OPERATED INSTRUMENTS large, heavy handles and inferior metal alloys , ivory or animal horns or bones Drawbacks :  cumbersome, awkward to use, ineffective  no uniformity of manufacture or nomenclature  effective sterilization was a problem
  7. 7. .  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
  8. 8. . Dr.Arthur.D.Black- developed many of the instruments and techniques  • Dr.Charles E.Woodbury- first to modify black’s instrumentation. Designed 39 sets of hand instruments for class III cavity preparations and condensing points for 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 pneumatic condenser
  9. 9. MATERIALS  Hand cutting instruments are manufactured from two main materials :Carbon steel and Stainless steel Stainless Steel carbon steel  Tungsten carbide, although hard and wear resistant, is brittle and cannot be used in all designs.
  10. 10. Stainless steel Chromium- 18% Carbon-1% Iron-81.4% Adv- Chromium in the alloy reduces tarnish and 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. Carbon steel Carbon-1% Manganeese-0.2% Silicon-0.2% Iron- 98.4-98.6% Adv- Harder and sharper than stainless steel Disadv- When unprotected, it will corode and fracture if instrument is dropped. Stellite Cobalt - 65- 90% Chromium - 35% Trace amounts tungsten, molybdenum, Iron. Adv- High resistance to acid Hardness Use- Manufacture of mixing and inserting instruments
  11. 11. MANUFACTURING PROCESS  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)
  12. 12. HEAT TREATMENT HARDENING TREATMENT • The steel is heated to 1500-16000 F (815degree C) in oxygen free enviornment and then quenched in a solution of oil. • Not more than 1-2mm of the tip is heated for hardening purpose, otherwise the instrument will lose its balance after Sharpening • Hardens the alloy, but it also makes it brittle, TEMPERING TREATMENT Quenched in solutions of oil, acid or mercury at 176 degree c for 10 min. Tempering is done to relieve strain and increase toughness of the alloy To accomplish this, the tip is reheated at a lower Temperature
  13. 13. Heat treatment Furnace
  14. 14.  G.V.BLACK- first acceptable nomenclature for and classification of hand instruments CUTTING NON-CUTTING a. Excavators - ordinary hatchet - hoes - angle formers - spoons b. Chisels - straight - curved - bin angle - enamel hatchet - GMT c. Other cutting insruments - Knives, carvers - files, scalers -Amalgam condensors - Mirrors - Explorers - Probes
  15. 15. CLASSIFICATION I) According to Charbenaeu: Operative instruments can be conveniently classified into 6 categories.
  16. 16. .1) Cutting instruments a) Hand  Hatchets  Chisels  Excavators  Others b) Rotary  Stones  Burs  Disks  Others 2)Condensing instruments Pluggers : Hand  Mechanical 3)Plastic instruments Spatulas Carvers Burnishers Packing instruments 4)Finishing and polishing instruments a)Hand : Orange wood sticks  Polishing points  Finishing strips b)Rotary  Finishing burs  Mounted brushes  Mounted stones  Rubber cups  Impregnated disks and wheels 5)Isolation instruments  Rubber dam frame  Clamps, forceps, punch  Saliva ejector  Cotton roll holder  Evacuating tips and equipment 6)Miscellaneous instruments  Mouth mirrors  Explorers  Probes  Scissors, pliers and others
  17. 17. CLASSIFICATION II) According to Marzouk: Instruments for operative dentistry procedures can be generally classified as 1) Those used for exploration 2) Those used for removal of tooth structure. 3) Those used for restoration of teeth.
  18. 18. ACC TO MARZOUK 1)Those used for exploration A) Dry the area on the teeth: This necessitates the use of an ● Air syringe. ● Pair of tweezers (pliers) ● Cotton pellets to dry the tooth. ● Cotton rolls – to isolate the area around the tooth.
  19. 19. B) Illuminate the area: A source of light could be either an overhead fixture supplying non-reflecting light or an intra-canal light. They can be – Battery operated lights. – Built in lights attached to dental unit. – Light attached to mirror or hand piece. Light can be introduced directly or indirectly by reflecting via a mirror.
  20. 20. C) To retract the soft tissues: The mouth mirror is used to move the tongue and cheek away. – Blunt plastic instruments may help in retraction. – Tongue depressor or retractors are also helpful for this procedure. D) To probe the potential lesion : Explorers are used for this purpose. These are 4 types of explorers. Straight explorer. Right angled explorer Arch explorer Inter-proximal explorer. E)Separartors
  21. 21. ACC TO MARZOUK 2) Those used for tooth structure removal:  Hand cutting instruments.  Rotary cutting and abrasive instruments.  Ultrasonic instruments 3) Those used for restoring:  Mixing instruments  Spatulas  Plastic instruments  Condensing instruments  Burnishing instruments  Carvers  Files  Knives  Finishing and polishing instruments.
  22. 22. NOMENCLATURE G.V. Black prescribed four classes similar to biological classification Order - purpose of the instrument. Sub order - position or manner of use Class - form of the blade. Subclass - shape of the shank NAMING GOES FROM 4-1 Bin angle hatchet push excavator
  23. 23. PARTS OF HAND CUTTING INSTRUMENTS  blade with cutting edge or nib with face(a)  shank (b)  Handle / shaft (c)
  24. 24. HANDLE / SHAFT  Length-5.5 inches  Diameter-5.5 mm  Available in various sizes and shapes- small, medium, large diameter  Cross-section Hexagonal octagonal  Handle designs Smooth serrated knurled for better grasping and developing pressure
  25. 25. .  Instrument formula incorporated on it  Manufacturing kit number incorporated on it  Handle is either continuous with shank or seperable
  26. 26. SHANK  Connects the shaft with the blade or working point or nib.  Smooth, round, tapered and contrangled  Have one or more bends to avoid the instrument from having tendency to twist in use where force is applied  G.V.Black classified instruments depending on the number of angles in the shank as-
  27. 27.  a Instruments classified by number of angles in the shank a) straight, b) monoangled , c) biangled , d) tripleangled e) quadrangled
  28. 28. CONTRANGLING & BALANCE  CONTRANGLE refers to shank in which two or more angles are necessary to bring working end into near alignment with( within 2 to 3mm ) the axis of handle.
  29. 29. Advantages  Prevent rotation  Modified access  Greater stability and balance  Ease of control Working end should be within 2-3mm
  30. 30. BLADE  Blade- is the part of the instrument bearing the cutting edge.  Connected to handle by shank.  Non cutting instruments- part corresponding to blade- is called NIB, end of the nib or working surface is called FACE
  31. 31. CUTTING EDGE  Cutting edge- is the working part of the instrument.  It is usually in the form of a bevel in different shapes.  Beveled- - single beveled - Bibeveled - Triple beveled -Circumferentially beveled  • Regular bevel- - distal to shaft  • Reverse bevel- - mesial to shaft eg:- binangle chisel Single bevelled bibevelled circumferentially bevelled
  32. 32. . DIRECT CUTTING 1)Force is applied in the same plane as that of the blade and handle. 2)Straight blade. 3)All the angles and curves in the shank are in same plane as the handle. 4)Used in direct and lateral cutting. LATERAL CUTTING 1)Force is applied at a right angle to the plane of the blade and handle. 2)Curved blade. 3)Angles or curves in a plane at right angle to the handle. 4)Can only be used in lateral cutting (scraping action).
  33. 33. INSTRUMENT FORMULA GIVEN BY G. V .BLACK FOR HAND CUTTING INSTRUMENTS 3 unit instrument formula.  Cutting edge of the instrument is at right angle to the blade  1. First unit Width of the blade in 1/10th of a mm.  2.Second unit Length of the blade in millimeter.  3. Third unit Angle the blade forms with the axis of the handle in centigrade. Instrument formula for enamel hatchet
  34. 34. 4 UNIT INSTRUMENT FORMULA  Cutting edge of the instrument is at an angle other than right angle to the blade  1. First unit Width of the blade in 1/10th of a mm.  2.Second unit angle the cutting edge forms with the axis of the handle in centigrade is primary cutting edge angle.  3. Third unit Length of the blade in millimeter.  4.fourth unit Angle the blade forms with the axis of the handle in centigrade.
  35. 35. FOUR NO. FORMULA( GINGIVAL MARGINAL TRIMMER)  13 – Blade width 1.3 mm  95 – Primary cutting edge angle in centigrade  8 - Blade length 8mm  14 - Blade angle
  37. 37. TYPES OF HAND CUTTING INSTRUMENT Chisels  Cutting edge of the instrument is at right angle to the axis of the handle of instrument  Used for planing or cleaving enamel 1. Straight chisel  No bend in the shank  Mono bevelled/triple bevelled  Minimal accessibility  Used with push stroke or lateral cutting action
  38. 38. . Monoangle chisel : -If the angle of the blade is less than 12.5 degree centigrade it is monoangle chisel. -Blade is shorter as compared to chisel - Single angle in the shank -Used with push stroke or lateral cutting action Hoe If the angle of the blade is more than 12.5 degree centigrade it is hoe Used with pull stroke Use : to define line and point angles in Class III and V preparations for direct filling gold .
  39. 39. . 3) Binangle chisel  Two angles in shank  Used to cleave or split undermined enamel  Reverse bevel instrument  Ring on the shank of chisel - Reverse bevel instrument.  Ring on the shank of hatchet – Right side instrument. 4) Triple angle chisel  Used to flatten the pulpal floor  Three angles in the shank .  May be mesially or distally bevelled.
  40. 40. . Ordinary Hatchet, bibevelled, hatchet excavator 1)Cutting edge is parallel to axis of the instrument. 2)Cutting edge at right angle to axis of blade 3)Monoangled 4)Length of the blade is very small. 5)Bibevelled 6)Used with push stroke. 7)Uses : To prepare retentive areas in anterior teeth 8)Sharpening internal line angles in direct filing gold preparations.
  41. 41. ENAMEL HATCHET  Blade larger, heavier and beveled on only one side, rather than the ordinary hatchet  Cutting edge in a plane parallel with the axis of the handle  Used for cutting enamel in proximal cavities and comes as right or left types for use on opposite sides of the preparation
  42. 42. .  Used for smoothening buccal and lingual walls of proximal box.  Used for breaking unsupported enamel of proximal box.  Used for smoothening gingival seat (lateral scraping motion).
  43. 43. . 3 Gingival marginal trimmer - modified enamel hatchet • Blade curved and primary cutting edge is at an angle • Right and left types- can be mesial or distal pairs • Second number in the formula • Used for rounding or bevelling of the axiopulpal line angle of two surface preparations
  44. 44. . 95-100- pair used on the distal gingival margin 85-75- pair used to bevel the mesial margin 100 & 75 pairs- for inlay/ onlay preparations with steep gingival bevels 90 & 85 pairs- for amalgam preparations with gingival enamel bevels that decline gingivally only slightly
  45. 45. .  The mesial gingival margin trimmer (13-85-10-14, R&L) or the distal gingival margin trimmer (13-95-10-14,R and L) is used to establish a slight cavosurface bevel at the gingival margin (20 degrees) declining gingivally to ensure full length enamel rods forming the gingival margin.  The sharp angles are rounded by rotational sweeping with a GMT.
  46. 46.  The cutting edge makes an acute angle with the edge of the blade farthest from the handle is termed distal and is used to bevel a distal gingival margin or accentuate a mesial axiogingival angle.  The cutting edge makes an acute angle with the edge of the blade nearer to the handle is called mesial and is used to bevel mesial gingival margin or accentuate a distal axiogingival angle.
  47. 47. ANGLE FORMER  Has four unit instrument formula  Paired instrument right and left  Ring on the shank - right side instrument  3 cutting edges ome primary cutting edge and two secondary cutting edges (blade is bevelled on sides and on edge)  used to accentuate line and point angles and creating retentive features in dentin in preparation for gold restorations.  Used in placing bevel on enamel margins. Combination of chisel and GMT Primary cutting edge
  48. 48. WEDELSTEDS CHISEL  Shank and blade are curved  Bevel on one side of blade  Bevel towards the curvature of blade – mesially bevelled  Bevel away from curvature of blade – distally bevelled  Used for cleaving undermined enamel and shaping walls  Single instrument with three cutting motion : Vertical , right and left
  49. 49. . Off angle hatchet  Instrument in which blade is rotated by 45 degrees from the plane of long axis of the instrument  Used to create and shape specific angulations for cavity walls, especially in areas of difficult access. Triangular chisel  Blade is triangular in shape with the base away from the shaft.  Has a terminal cutting edge like straight chisel.  Functions -
  50. 50. SPOON EXCAVATOR  Modified hatchet  Double ended instrument  Binangle/triple angle  Paired(right and left)  Double plane instrument  Circumferentially bevelled  Cutting edge either circular (discoid carver) or claw like (cleoid carver)  Use scooping of softened carious material  Carving amalgam or direct wax patterns
  51. 51. OTHER CUTTING INSTRUMENTS  Knives - finishing knives, amalgam knives, or gold knives  Knives are used for trimming excess restorative material on the gingival, facial, or lingual margins of a proximal restoration or trimming and contouring the surface of a Class V restoration.  Sharp secondary edges on the heel aspect of the blade are very useful in a scrape-pull mode. Amalgam knives
  52. 52. OTHER HAND CUTTING INSTRUMENTS Examples of other hand instruments for cutting. A, Finishing knife. B, Alternative finishing knife design emphasizing secondary cutting edges. C, Dental file. D, Cleoid blade. E, Discoid blade carving amalgam.
  53. 53. FILES  Files also can be used to trim excess restorative material.  They are particularly useful at gingival margins.  Blades of files are very thin, and teeth on the cutting surfaces are short.  The teeth of the instrument are designed to make the file either a push or a pull instrument.
  54. 54. MOUTH MIRRORS Flat mirrors- most commonly used and preferred for most procedures, concave (magnifying) mirrors are also available. • Two main types- rear-surface and front-surface reflecting mirrors. • The rear surface mirror - Reflecting surface is on the back surface of the mirror lens. - Surface is less easily scratched. - Produces a double or ghost image.
  55. 55. . • 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. • Rear surface mirror can be used for general purposes and for retracting the tongue and cheeks, reserving the front surface mirror for detailed examination. Mirrors used for indirect vision
  56. 56. Different sizes of mirrors Depending on diameter of head tops of mirrors sizes given are no.2,3 and 4.
  57. 57. 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.
  58. 58. . Uses 1) Indirect illumination. - Mouth mirror could be held at an angle to reflect the light onto the working area 2) Retraction - Mirror head used to retract the patient’s lip or check or tongue so that the clinician is able to view tooth surfaces. -3)Protects from injury. 4) Indirect vision. 5) Guard. 6) Trans illumination. - Only maxillary and mandibular anterior teeth can be transilluminated 7) to check mobility,depressibility. 8) for performing percussion test
  59. 59. Mouth mirrors with illumination
  60. 60. Mouth mirrors with suction
  61. 61. EXPLORER  used as a diagnostic aid in evaluating condition of teeth especially pits and fissures Parts :  Handle - is straight, could be plain or serrated.  Shank - curved with one/more angle  Working tip or tine is pointed. Types of Explorer  Straight explorer  Shepherd’s Crook or curved explorer  Interproximal explorer/Briault explorer/Back action probe
  62. 62. USES - Exploring lesion - For detecting and assessing carious lesion in the tooth - Detecting demineralised 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
  63. 63. Periodontal Probes Though they almost look like explorers but they have blunt end which is marked with gradations. They are used for measuring pocket depth and tooth preparations. In operative dentistry used to determine dimensions of instruments and various features of preparations or restorations a)Straight probe b)briault probe c) Graduated probe d) furction probe e)CPITN probe
  64. 64. TWEEZERS  These have angled tip and are available in different sizes.  They are used to place and remove cotton rolls and other small materials. Cotton pliers and locking tweezers Articulating paper forceps
  65. 65. RESTORATION INSTRUMENTS  Following are the commonly used instruments when temporary or permanent restoration is to be mixed. Cement Spatulas  Several types of spatulas are available in the market differing in shape and size . On the basis of size, cement spatula can be classified into two types : Large and small cement spatula
  66. 66. .  1. Large cement spatula: Mixing of luting cements  2. Small cement spatula: Mixing of liner Cement spatula also can be classified on the basis of thickness such as rigid and flexible. Their use depends on viscosity of cement and personal preference. Different types of cement spatulas
  67. 67. PLASTIC FILLING INSTRUMENT  Instruments used for carrying the mixed base cements which are in soft stage from cement spatula to the cavity  They are used to mix, carry and place cements  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.
  68. 68. CONDENSERS  Come in single and double-ended designs. 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. Mechanical type Hand type
  69. 69. . Nibs may be -Of different shapes 1) Round 2) Elliptical 3) Diamond 4) Triangular 5) Paralellogram 6) Rectangular -Of different sizes Large round condensors Small round condensors -Depending on working end (condensor face) Serrated – for direct filling gold Smooth – for silver amalgam restorations
  71. 71. GOLD CONDENSORS  Hand condensors-  Handle six inch in length.  Has one blunt end to receive blow from the mallet.  Shank may be straight, monoangled or offset.  Nibs can be round, rectangular and parallelogram shaped.  Pyramidal or wedge like serrations are present on the face of condensors to increase their surface area
  72. 72. .  Hand mallet- long handled condensors with leather faced malets (50 gms in weight)  Automatic hand mallet-spring loaded instrument is used  Electric malleting-(Mc Shirley electromallet)  Pneumatic mallet(Hollenbeck condensor) Vibrating condensors with detachable tips run by compressed air
  73. 73. AMALGAM CARRIERS  Carry the freshly prepared amalgam restorative material to the prepared tooth.  Have hollow working ends, called barrels, into which the amalgam is packed for transportation  Carriers can be both single and double ended. Barrel of amalgam carriers comes in a variety of sizes viz ; small, large and jumbo  Lever of amalgam carrier is located on the top of the carrier. When lever is depressed, the amalgam is expelled into the preparation.
  74. 74. CARVERS  Carvers are used to contour the restoration approximately same to original tooth structure.  Sharp cutting edges present in carvers are used to shapen and form tooth anatomy from a restorations.  Carvers come in different shapes and sizes in double ended designs
  75. 75. . - Hollenback carver (Knife- edged – elongated bibevelled) - Diamond (Frahm’s) carver – Bibevelled cutting edge - Wards ‘C’ carver - Discoid- cleoid - Interproximal carver  Hollenback, Diamond and Wards - One blade is parallel to the long axis of the instrument and the other is perpendicular to the long axis of the instrument
  76. 76. BURNISHER  used for: • Final condensation of amalgam. • Initial shaping of occlusal anatomy of amalgam. Shape metal matrix bands to impart more desirable contour to the restorations  Commonly used are: small ball burnisher Rounded cone-shaped burnisher. Beavetail or egg shaped condenser—narrow type of burnisher. Ovoid burnisher—comes in various sizes such as 28,29, 31.
  77. 77. Beaver tail shaped Round shaped Egg shaped
  79. 79. P K T INSTRUMENTS  P.K. Thomas Waxing Instrument Set, 5 pcs, L-PKT. The feather weight aluminum handle offers extremely comfortable handling to reduce hand and wrist fatigue. Color coded: Yellow (PKT 1), Green (PKT 2), Blue (PKT 3), Red (PKT 4) and Silver (PKT 5). The set comes in a nice hard plastic case.
  80. 80. COMPOSITE RESIN INSTRUMENTS  A wide range of double ended instruments are used to transport and place resins.  The working ends on these instruments range from varying small cylinders to angled, paddle like shapes  Composite resin instruments are made of plastic or titanium nitride coating.  They do not discolor or contaminate the composite restoration, also the composite resin material does not stick to the instrument.
  81. 81. Hand instruments for composites
  82. 82. Top tips from Dentsply • The special surface of Dentsply Ash composite materials enables them to be used with composite and glass ionomer materials. • Anodised aluminium • Placing and shaping composite material is significantly easier and quicker • The anodised surface of the composite instrument is not scratched by the composite filler particles and it also resists composites sticking to it without risk of discolouring the materials. • Dentsply Ash composite instrumentsare available in Ceramicolor and Lustra.
  83. 83. Optra contact- Ivoclar vivadent OptraContact is easy to use and highly effective. The instrument is used to achieve large and tight proximal contacts in posterior teeth.
  84. 84. OptraContact features a patented forked working end with which a composite bridge is formed while the first layer is cured. The bridge, which is created in the contact region, stabilizes the matrix. Furthermore, OptraContact allows contacts to be selectively created in the anatomically-correct upper third of the proximal surface. OptraContact is available in two sizes: one for molars and one for premolars or for large and small cavities.
  85. 85. Advantages Tighter and larger proximal contacts The stabilizing composite bridge makes the proximal contacts tighter and larger. Selective positioning of contacts Contacts can be selectively positioned in the upper third of the proximal surface. Consequently, the entire restoration is located much nearer to the original natural position
  86. 86. OPTRASCULPT PAD  Optrasculpt pad is a contouring instrument with special form pad of attachments which is designed for the efficient, nonstick forming and shaping of composites.  Highly synthetic foam pads  Nonstick surface of the foam pad attachments prevents the adhesion of composite resin  Suitable for adapting, contouring uncured packable composite and compomer materials in class 3, 4 and 5 restorations and direct laminate veneers
  87. 87. #3 Goldstein Flexi-Thin XTS Composite Instrument with #6S Smooth Satin Steel Handle NB Anterior Composite placement instrument
  88. 88. Garrison Dental universal Composite & plastic filling instruments
  89. 89. Slix™ Composite Manipulation Instruments Nonstick - Durable – Ergonomic - Autoclavable The tips are treated with a revolutionary protective coating that provides superior non- stick properties and a lustrous surface for long lasting esthetic appearance. No more composite sticking; dentists appreciate the easy placement and fast clean-up! The ergonomic handles are manufactured from an advance technology polymer with medical-grade silicone grips. “Surprisingly light”-only 16g - on the largest available handle (1/2” (1.27 cm) diameter) to reduce hand fatigue
  90. 90. INSTRUMENT GRASPS  correct instrument grasps are important for achieving success in operative procedures  correct grasp is selected according to the instruments being used, position of instrument being used, the operator, the area which is being operated and the specific procedure to be done. Commonly used instrument grasps in operative dentistry 1. Modified pen grasp 2. Inverted pen grasp 3. Palm and thumb grasp 4. Modified palm and thumb grasp.
  91. 91. Modified pen grasp Inverted pen grasp Palm and thumb grasp
  92. 92. RESTS  Helps to stabilize the hand and the instrument by providing a firm rest to the hand during operative procedures.  Finger rests may be intraoral or extraoral Intraoral finger rests: a. Conventional b. Crossarch c. Opposite arch d. Finger on finger
  93. 93. .  2. Extraoral finger rest: It is used mostly for maxillary posterior teeth.  a. Palm up b. Palm down 
  94. 94. GUARDS- • Hand instruments or other items, such as interproximal wedges, used to protect soft tissue from contact with sharp cutting or abrasive instruments.
  95. 95. SHARPENING OF HAND INSTRUMENTS  Instrument sharpening is a critical component of operative dentistry  A sharp instrument cuts more precisely and quickly than dull instruments.  Therefore to avoid wasting time on using dull instruments, dentists must be thoroughly familiar with principles of sharpening
  96. 96. GOALS OF SHARPENING  • To produce a functionally sharp edge.  • Maintain the contour (shape) of instrument.  • Maintain the life of instrument. Advantages of Sharp Instruments • Improved efficiency. • Improved tactile sensations. • Less pressure and force. • Improved instrument control. • Minimized patient discomfort. • Less treatment time.
  97. 97. PRINCIPLES OF SHARPENING Select the appropriate type of stone for type of instrument to be used. • Instrument should be clean and sterile before sharpening. • Establish proper angle between stone and surface of instrument on the basis of design. • Lubricate the stone during sharpening as it reduces the clogging of sharpening stone and heat generated during sharpening. • Stable and firm grip of both instrument and stone is required during sharpening. Maintain the proper angulation throughout sharpening strokes.
  98. 98. . • Sharpening should be done with light stroke or pressure. Avoid excessive pressure. • When sharpening is completed observe the cutting edge for wire edges. Wire edges should be removed. (Wire edges are unsupported metal fragments that extend beyond the cutting from the lateral side or face of blade). • Resterilize the sharpened instruments.
  99. 99. DEVICES USED FOR SHARPENING  Mechanical bench type piece of equipment in which honing disks On top disk rotates up to 7,000 rpm. e.g. honing machine.  Mounted Stones In this, stones are mounted on metal mandrel and used with slow speed handpiece. Most common mounted stones are Arkansas and ruby.. Mechanical sharpners
  100. 100. Various shapes such as cylindrical,conical or disk shaped are available. Mounted stones are not preferred in routine because they: 1. Tend to wear down quickly. 2. Result in generation in frictional heat. 3. Difficult to control during sharpening
  101. 101. .  Unmounted/Handhold Stones  come in variety of sizes and shapes. Stone can be rectangular with flat, rectangular with grooved surfaces or cylindrical in shape.  Flat stone is ideal for moving technique.  Cylindrical stone for removing wire edges
  102. 102. .  Stone type can come in natural or synthetic form:  1. Natural–Arkansas (preferred)  2. Synthetic • India stone • Ceramic stone • Composition stone
  103. 103. STERILISATION AND DISINFECTION STERILISATION – Destruction of both 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)sterilisation  5)sterilisation monitoring  6)drying or cooling  7)storage  8)distribution  9)sharpening
  104. 104. . Presoaking- Prevent drying Begin to dissolve or soften organic debris Begin microbial kill in some instances Presoak solution contains -Detergents -Enzymes or detergent containing disinfectant such as phenolic compounds or quaternary ammonium compounds.
  105. 105. Cleaning Manual: hand scrubbing with soft brush under water to prevent aerolising and splashing Ultrasonic : safest and most efficient way to clean
  106. 106. . 3)Corrosion control and lubrication A rust inhibitor should be applied on non stainless steel instruments. Lubrication of instruments with moving parts should be done prior to steam sterilisation Water based lubricants that contain preservative are ideal.
  107. 107. 4)Packaging- Cleaned instrument are wrapped before sterilisation -See through poly film bag -Single layer cloth wrap -Nylon plastic tubing 5)Instruments in tray and cassette Retain instruments at chair side and during ultrasonic cleaning, rinsing and sterilisation
  108. 108. . 5)Sterilisation 4 accepted methods -steam pressure sterilisation(autoclave) -Chemical vapor pressure sterilisation(chemiclave) -Dry heat sterilisation(dryclave) -Ethylene oxide sterilisation -New methods Microwave Ultraviolet light
  109. 109. STEAM PRESSURE STERILISATION  Time required  -15 min at 250 degree F(121 degree C) and 15 lbs pressure  Most rapid and effective method of sterilising cloth surgical packs and towel packs. Disadvantages:  Items sensitive to elevated temperature cannot be sterilised  Tends to rust carbon steel instruments and burs.
  110. 110. CHEMICAL VAPOR STERILISATION (CHEMICLAVE)  Operate at 270 degree F(131 degree C) at 20 lbs for half an hour  Carbon steel and burs are said to be sterilised without getting rusted. -Disadvantages Only dry instruments should be loaded Towels and heavy cloth wrapping may not be penetrated to provide adequate sterilisation.
  111. 111. DRY HEAT STERILISATION Conventional dry heat oven  -heated at 320 degree F(160 degree C) for 30 min.  Instruments should be packaged in foil wrap or nylon bags. Short cycle high temperature by dry heat oven Sterilisation time reduced -6 min for unwrapped -12 min for wrapped Temperature – 370-375 degree F.
  112. 112. ETHYLENE OXIDE STERILISATION  Best method for sterilising complex instrument and delicate materials.  Expensive  DISINFECTION Boiling water – 10 min Use of chemicals-6 to 10 hrs glutaraldehyde-2-3% Sodium hypochlorite 1-5%
  113. 113. . 6)Sterilisation monitoring Sterilisation 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
  114. 114. CONCLUSION  The removal and shaping of tooth structure are essential aspects of restorative dentistry. Modern high speed equipments has eliminated the need for many hand instruments for tooth preparation , but hand cutting instruments are still important for finishing many tooth preparations and thus hand cutting instruments remain an essential part of the armamentarium for quality restorative dentistry.
  115. 115. References • Sturdevant’s Art and Science of Operative dentistry (4th edition) • Operative dentistry- modern theory and practice-Marzouk, Simonton and Gross (1st edition) • Principles and practice of Operative dentistry by Gerald T.Charbenau (2nd edition) • Atlas of operative dentistry- William W Howard, Richard C Moller (3rd edition) • History of dentistry- Melvin E Eing • Text book of operative dentistry- Gilmore, Lund, Bales, Vernetti (4th edition) • Current concepts in Operative dentistry- Goldman, Gilmore, Inby, McDonald (6th volume) • Modern concepts in operative dentistry- Horsted, Ivar, Mjor • Pickard’s manual of operative dentistry (5th edition) • Mosby Dental hygiene – Michele L Darby (5th edition)