Hand instruments in operative dentistry 2 nd yr

Presentation on hand instruments used in operative dentistry.
Credits to everyone who contributed to literature

1. HAND INSTRUMENTS IN OPERATIVE DENTISTRY PRESENTED BY- Dr. Sanket Hans Pandey PG Student, Department of Conservative Dentistry and Endodontics

2. CONTENTS INTRODUCTION MATERIALS USED CLASSIFICATION INSTRUMENT PARTS INSTRUMENT NOMENCLATURE INSTRUMENT FORMULA TYPES OF HAND CUTTING INSTRUMENTS INSTRUMENT GRASP SHARPENING OF HAND INSTRUMENTS

3. INTRODUCTION A dental instrument is an appliance, or tool by means of which a dentist performs dental operations. Broadly classified as - a.Hand instruments- instruments that are hand held when used. b.Rotary instruments- are operated in a handpiece which in turn is hand held.

4. MATERIALS USED CARBON STEEL It is harder than stainless steel but corrodes easily and posses more chance of being fractured due to dropping. Carbon-1% Manganeese-0.2% Silicon-0.2% Iron- 98.4-98.6 % STAINLESS STEEL Stainless steel alloy contains 72 to 85% iron, 15 to 25% chromium and 1 to 2% carbon. Stainless steel remains bright under most conditions , but loses a keen edge during use much more quickly than does carbon steel. Commonly used nowdays due to its more sterlization friendly properties.

5. CLASSIFICATION BY STURDEVANT HAND INSTRUMENTS CUTTING NON CUTTING OTHERS CHISELS EXCAVATORS AMALGAM CONDENSORS MIRRORS EXPLORERS PROBES ORDINARY HATCHET HOE ANGLE FORMER SPOON STRAIGHT CURVED OR BINANGLE ENAMEL HATCHET GMT KNIVES FILES SCALERS CARVERS

6. PARTS OF INSTRUMENTS HANDLE (c) SHANK (b) BLADE (a)

7. HANDLE It is the portion of the instrument where the operator holds the instrument. They are usually straight and may have serrations for better grip. Handles are available in various sizes and shapes.

8. A variety of handle configurations are available . Padded handles are said to increase operator comfort and grip during use. The standard metal handle has a diameter of approximately ¼ inch (6.4 mm). (9.5-mm) diameter handle are said to be more ergonomic and less likely to contribute to the development of carpal tunnel syndrome. A handle with an intermediate diameter (5/16 inch or 7.9 mm) is also available. The larger diameters are encouraged primarily for dental hygienists, who spend a large part of their day using hand instruments. A drawback to the use of larger handles in operative dentistry is the space they consume in an instrument tray.

9. Standard stainless steel handle with a diameter of approximately 6.4 mm. Padded handle with diameter of 8mm Large handle with a dimater of 9.5mm

10. SHANK The shank joins the blade to the handle of the instrument and is angled to keep the working end of the blade within 2 to 3 mm of the axis of the handle. This angulation is intended to provide balance, so that when force is exerted on the instrument it is not as likely to rotate, which would decrease the effectiveness of the blade and could possibly cause damage to the tooth or soft tissue.

11. Dr. G.V. Black classified instruments based on the number of shank angles as straight mon o angle (one ), bin-angle (two) triple-angle (three ) quadrangle ( four)

12. Blade/Nib It is the working part of the instrument. It is connected to the handle by the shank. For non-cutting instruments, the working part is termed the nib and is used to place, adapt and condense the materials in the prepared tooth. Depending on the materials being used, the surface of the nib may be plain or serrated.

13. NOMENCLATURE An order name describes that for which an instrument is used, as for example, excavator, pluggers , burnishers, A sub-order name describes where or how an instrument of a given order is used and is made by inserting a prefix before the order name. Examples, hand pluggers push or pull scalers , etc.

14. CLASS The class describes the form or shape of the cutting edge: a- Chisel b- Hatchet c- Hoe d- Gingival margin trimmer

15. SUBCLASS The subclass delineates the angle or angles of the shank of the instrument: a- Straight - no angle b- Mono angle - one angle c- Bin angle - two angles d- Triple angle - three angles

16. Instrument Formula Given by Dr. G.V. Black. Cutting instruments have formulas describing the dimensions and angles 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., 10-8.5-8-14 ) The first number indicates the width of the blade or primary cutting edge in tenths of a millimeter (0.1 mm ) .( e.g., 10 = 1 mm ) The second number of a four-number code indicates the primary cutting edge angle, measured from a line parallel to the long axis of the instrument handle in clockwise centigrades . The angle is expressed as a percent of 360 degrees (e.g., 85 = 85% × 360 degrees = 306 degrees ) If the edge is locally perpendicular to the blade, this number is normally omitted, resulting in a three-number code.

17. The third number (second number of a three-number code ) indicates the blade length in millimeters (e.g ., 8 = 8 mm ) The fourth number (third number of a three number code ) indicates the blade angle, relative to the long axis of the handle in clockwise centigrade (e.g ., 14 = 50 degrees).

18. EXCAVATORS Excavators are designed for the excavation and removal of carious dentin and for the shaping of the internal parts of cavities . INSTRUMENTS

19. They have the edge of the blade running in a direction parallel with the handle. They are usually single-planed bibevelled instruments. Instrument formula – (3-2-28) USES- on anterior teeth for preparing retentive areas sharpening internal line angles, particularly in preparations for direct gold restorations. ORDINARY HATCHET

20. HOE EXCAVATORS The hoe excavator has the primary cutting edge of the blade perpendicular to the axis of the handle. Used in a PULL motion. Instrument formula –(4 ½- 1 ½ - 22) U sed for- planing tooth preparation walls forming line angles Commonly used in Class III and V preparations for direct gold restorations.

21. ANGLE FORMER A special type of excavator is the angle-former . It is monoangled and has the primary cutting edge at an angle (other than 90 degrees) to the blade. It may be described as a combination of a chisel and a gingival margin trimmer. It is available in pairs (right and left) It is a triple beveled instrument. They cut in vertical, push or pull motion. Instrument formula- (12-85-5-8) Uses - 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 .

22. SPOON EXCAVATOR It has a semicircular cutting edge. The blades are slightly curved, and the cutting edges are either circular or clawlike . The circular edge is known as a discoid, whereas the clawlike blade is termed a cleoid . The shanks may be bin-angled or triple-angled to facilitate accessibility. USES - used for removing caries carving amalgam or direct wax patterns.

23. CHISEL

24. STRAIGHT CHISEL 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. The shank and blade of the chisel also may be slightly curved ( Wedelstaedt design) or may be bin-angled. 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 because a 180-degree turn of the instrument allows for its use on either side of the preparation.

25. 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. The blade with a distal bevel is designed to plane a wall that faces the blade’s inside surface. The blade with a mesial bevel is designed to plane a wall that faces the blade’s outside surface

26. ENAMEL HATCHET These are single planed paired instruments (right and left type) It can be binangled , triple angled or parallel with shaft. Used with push/pull vertical movements. It is beveled on one side. Used to cut or cleave undermined enamel in proximal cavities and on buccal or lingual walls.

27. GINGIVAL MARGIN TRIMMER The gingival margin trimmer is designed to produce a proper bevel on gingival enamel margins of proximoocclusal preparations. It is similar in design to the enamel hatchet except the blade is curved and the primary cutting edge is at an angle (other than perpendicular) to the axis of the blade. It is made as right and left types. It also is made so that a right and left pair is either a mesial pair or a distal pair. When the second number in the formula is 90 to 100, the pair is used on the distal gingival margin.

28. When this number is 75 to 85, the pair is used to bevel the mesial margin.

29. OTHER CUTTING INSTRUMENTS Knives Files Cleoid blade Discoid blade

30. KNIVES Knives, known as finishing knives, amalgam knives, or gold knives, are designed with a thin, knifelike blade that is made in various sizes and shapes. 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.

31. FILES Files also can be used to trim excess restorative material. They are particularly useful at gingival margins. Blades of files are extremely thin, and teeth on cutting surface are short. The teeth of the instrument are designed to make the file either a push or a pull instrument. Files are manufactured in various shapes and angles to allow access to restorations.

32. DISCOID-CLEOID BLADE The discoid- cleoid instrument is used principally for carving occlusal anatomy in unset amalgam restorations. It also may be used to trim or burnish inlay- onlay margins. The working ends of this instrument are larger than the discoid or cleoid end of an excavator.

33. NON CUTTING INSTRUMENTS Amalgam carrier Condensor Burnisher Carver Mouth mirror Explorer Probes

34. Amalgam Carrier For dental amalgam restorations, amalgam is placed into the preparation with an amalgam carrier , an instrument with a hollow cylinder that is filled with amalgam. A plunger operated with a finger lever pushes the amalgam out of the carrier into the preparation . Amalgam carriers are usually supplied as double-ended instruments. They are available in several different diameters; for example, mini is 1.5 mm; regular (medium) is 2.0 mm; large is 2.5 mm; and jumbo is 3.0 to 3.5 mm. These are the approximate inside diameters of the cylinders of amalgam carriers and may vary slightly from manufacturer to manufacturer .

35. After restoration is completed, any remaining amalgam alloy is expelled out from the carrier into the amalgam well , otherwise carrier will no longer be serviceable if the amalgam is allowed to harden in the carrier. A poorly packed amalgam carrier may result in amalgam fall out before it is ejected into the prepared tooth.

36. CONDENSOR Condensers are used to compress amalgam or to push resin composite or glass- ionomer materials into all areas of the preparation. The working ends, or nibs , of condensers may be any shape, but usually they are round with flat ends . Condensers can be hand or mechanical in nature .

37. BURNISHER Burnishers are used for several functions. The word burnish is defined as “to make shiny or lustrous, especially by rubbing; to polish” and “to rub (a material) with a tool for compacting or smoothing or for turning an edge. Used to - to smooth and polish the restoration. remove scratches left on the amalgam surface by a carving instrument. Burnishers have smooth round end and come in single or double end. Different types of burnishers are available but most commonly used are PKT3—designed by Peter K Thomas —Rounded cone-shaped burnisher. • Beavertail condenser—narrow type of burnisher. • Ovoid burnisher

38. Beavertail Burnisher used for final condensation of amalgam and the initial shaping of the occlusal anatomy in amalgam. The beavertail burnishers are useful for burnishing margins of cast gold restorations. PKT3 (rounded cone-shaped) burnisher, designed by Peter K. Thomas as a waxing instrument but useful in placing direct restorations as well; its rounded end and cone shape allow it to serve most functions that a small ball-shaped burnisher would serve, plus others

39. Carver Carvers are used to shape amalgam and resin composite and other toothcolored materials after they have been placed in tooth preparations. In general, when a convex amalgam contour is being carved , a concave-shaped carver facilitates the shaping or carving. Likewise, a convex carver facilitates carving of a concave shape. A convex carver may be used to carve a convex surface; the surface is carved tangentially, with multiple strokes. Whether a carver is used to carve amalgam or resin composite, it is important that the blade be sharp.

40. The cleoid -discoid (or discoid- cleoid ) carvers shown are used primarily for occlusal carving in amalgam restorations. The Walls no. 3 carver is useful for carving occlusal surfaces; the end that is shaped like a hoe is also useful for shaping cusps and for carving facial and lingual surfaces of large amalgam restorations. The Hollenback no. ½ carver is useful for occlusal , proximal, and axial (facial and lingual) surfaces.

41. The interproximal carver (IPC) has very thin blades and is extremely valuable for carving proximal amalgam surfaces near the interproximal contact area, as well as those surfaces mentioned for the Hollenback carver. Frahm’s Carver(DIAMOND CARVER) is to used to carve the occlusal surface of amalgam restorations.

42. MOUTH MIRROR For every procedure performed in the mouth, the dentist must have clear and distinct vision of the field When needed, the mouth mirror allows the operator to visualize areas of the mouth that he or she would not otherwise be able to see. It also allows the operator to maintain a body position that will reduce health problems associated with poor posture . The mouth mirror can also serve as a retractor of soft tissue (tongue, cheeks, or lips ) to aid access and visualization

43. For clarity of vision, the reflective surface of the mirror should be on the external surface of the glass. This type of mirror is called a front-surface mirror. Mouth mirrors are usually round and come in a variety of sizes. The most widely used sizes for adults are the no. 4 and no. 5. For constricted areas in posterior regions of the mouth, when a rubber dam is in place, a smaller mirror, such as a no. 2, is helpful.

44. Types of Mouth Mirror • Front surface reflecting mirror: Here the coating is present on front surface of the mirror to prevent image distortion. Rear surface reflecting mirror: It is most commonly used mirror . In this, coating is present on back side of the mirror • Plane or flat surface: It provides clear image without distortion • Concave surface: It is used to provide different degrees of magnification , but it causes image distortion • One sided : Image on one side • Two sided : Image on either side Advantage of 2 sided mirror is retraction with indirect vision simultaneously

45. EXPLORER Explorers. Explorers are pointed instruments used to feel tooth surfaces for irregularities and to determine the hardness of exposed dentin. The explorer that is used most often is the shepherd’s hook, or no. 23, explorer. Another useful shape is a cowhorn explorer, which provides improved access for exploring proximal surfaces. The no. 17 explorer is also useful in proximal areas

46. PROBES Probes are used in restorative dentistry to determine the dimensions and features of preparations and restorations. 3 commonly used probes are Williams probe PCP 12 probe PSR probe (periodontal screening and recording) Main differences between these probes are based upon- Position of millimeter marking Differences in diameters Configuration of marking (notched or painted)

47. PCP 12 Probe Williams Probe PSR Probe

48. Modified Pen Grasp The grasp that permits the greatest delicacy of touch is the modified pen grasp It is similar, but not identical, to that used in holding a pen The pads of the thumb and of the index and middle fingers 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 palm of the hand generally is facing away from the operator. The pad of the middle finger is placed near the topside of the instrument; by this finger working with the wrist and the forearm, cutting or cleaving pressure is generated on the blade.

49. Inverted Pen Grasp The finger positions of the inverted pen grasp are the same as for the modified pen grasp. The hand is rotated , however, so that the palm faces more toward the operator . This grasp is used mostly for tooth preparations employing the lingual approach on anterior teeth.

50. Palm-and-Thumb Grasp The palm-and-thumb grasp is similar to that used for holding a knife while paring an apple. The handle is placed in the palm of the hand and grasped by all the fingers, while the thumb is free of the instrument, and the rest is provided by supporting the tip of the thumb on a nearby tooth of the same arch or on a firm, stable structure. For suitable control, this grasp requires careful use during cutting . An example of an appropriate use is holding a handpiece for cutting incisal retention for a Class III preparation on a maxillary incisor

51. Modified Palm-and-Thumb Grasp The modified palm-and-thumb grasp may be used when it is feasible to rest the thumb on the tooth being prepared or the adjacent tooth. The handle of the instrument is held by all four fingers, whose pads press the handle against the distal area of the palm and the pad and first joint of the thumb . Grasping the handle under the first joints of the ring finger and little finger provides stabilization. This grip fosters control against slippage.

52. Sharpening of hand instruments Why to sharpen the instrument? A dull instrument can- cause more pain prolong operating time difficult to control reduce quality and precision in tooth preparation

53. Sharpness Test Scrape Test Sharpness of an instrument can be tested by lightly resting the cutting edge on a hard plastic surface. If the cutting edge digs in during an attempt to slide the instrument forward over the surface, the instrument is sharp. If it slides, the instrument is dull. Only very light pressure is exerted in testing for sharpness. Thumbnail Test Hold the sharpened edge of the instrument at 45 degree to the thumbnail Exert mild pressure on the instrument, if it slips along the nail, it is blunt. If the instrument shaves or grabs the nail, it is sharp

54. PRINCIPLES OF SHARPENING Sharpen instruments only after they have been cleaned and sterilized. Establish the proper bevel angle (usually 45 degrees) and the desired angle of the cutting edge to the blade before placing the instrument against the stone, and maintain these angles while sharpening. Use a light stroke or pressure against the stone to minimize frictional heat. Use a rest or guide whenever possible. Remove as little metal from the blade as possible. After sharpening, resterilize the instrument along with other items on the instrument tray setup. Keep the sharpening stones clean and free of metal cuttings.

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