Operative Dentistry Instruments PDF

OPERATIVE DENTISTRY HAND CUTTING INSTRUMENTS—-------- - INSTRUMENTS refers to a wide variety of highly specific instruments held in hand and applied during the actual treatment procedure. A. Ope...

OPERATIVE DENTISTRY HAND CUTTING INSTRUMENTS—-------- - INSTRUMENTS refers to a wide variety of highly specific instruments held in hand and applied during the actual treatment procedure. A. Operative Instruments B. Prophylaxis and Diagnostic C. General Surgical Instruments OPERATIVE INSTRUMENTS—-------- -------- 1. CUTTING INSTRUMENTS Hand cutting instruments are manufactured from two Hand – cutting instruments main materials : ○ Hatchets 1. CARBON STEEL ○ Chisels ○ harder than stainless ○ Hoes ○ when unprotected, may corrode more ○ Excavators quickly than stainless steel Rotary – cutting instruments 2. STAINLESS STEEL ○ Burs ○ remains bright under most conditions ○ Stones ○ loses a keen edge when used much ○ Discs 2. CONDENSING INSTRUMENTS INSTRUMENT DESIGN Pluggers 1. Blade / Nib ○ Hand 2. Handle ○ Mechanical 3. Shank 3. PLASTIC INSTRUMENTS Spatulas Parts of Hand Instrument: plastic filling instruments Carvers cement carriers Burnishers 4. FINISHING AND POLISHING INSTRUMENTS Rotary ○ Finishing Burs ○ Mounted Brush ○ Rubber Cap ○ Impregnated Disk & Wheels Hand BLADE / NIB - point or head. functional end ○ Finishing Strips ○ connected to handle by shank ○ Polishing points ○ in the form of a bevel (acute angle) ○ Orangewood sticks that cuts into tooth structure 5. ISOLATION INSTRUMENTS HANDLE (SHAFT) - Available in various size Rubber dam frame and shapes Clamp ○ Early hand instruments handles are Forceps quite large punch ○ in diameter Saliva Ejector, ○ North America Evacuating Tips & Equipment Small in diameter (5.5mm) and Cotton Roll Holder light 6. MISCELLANEOUS INSTRUMENTS Eight sided and knurled mouth mirrors ○ Europe - Larger in diameter and explorers tapered probes scissors Pliers SHANK - Connects the handle to the working ends of the instrument ○ smooth round and tapered ○ must be balanced and sharp Balance is accomplished by designing the angle of the shank so that the cutting edge of the blade must not be off axis by more than 1 – 2 mm  OPERATIVE DENTISTRY CUTTING INSTRUMENT: BEVELS I. CUTTING INSTRUMENT A. Excavator A. EXCAVATOR: 4 Subdivisions 1. Ordinary Hatchets 2. Hoes 3. Angle Former 4. Spoons ORDINARY HATCHET (3 - 2 - 28) the cutting edge directed in the same plane as that of the long axis of the handle and is bibeveled used primarily on anterior teeth for preparing retentive areas & sharpening internal line angles HOE Cutting edge of the blade perpendicular to the axis of the handle. Planning for tooth preparation walls and forming line angles. Class III and V preparation INSTRUMENT NAMES (NOMENCLATURE) 1. According to function - e.g. scaler, excavator ANGLE FORMER 2. According to manner of use - e.g. hand Used primarily for defining line angles condenser and creating retentive features in 3. According to design of working end - e.g. dentin. spoon excavator, sickle scaler Used in placing bevel in the enamel Described as a combination of a gingival trimmer and chisel SPOON EXCAVATOR Used for removing caries and carving amalgam or direct wax patterns. Cutting edges are circular or claw-like. Discoid -circular edge Cleoid-claw-like edge B. CHISELS: 3 Subdivisions 1. Straight 2. Slightly Curved ( Wedelstaedt ) 3. Enamel Hatchets 4. Gingival Margin Trimmers 5. Bin angle FIRST NUMBER- width of the blade or primary cutting edge in tenths of a millimeter STRAIGHT CHISEL (0.1mm) Straight shank and blade, with the ○ e.g., 10 = 0.1mm bevel on only one side. SECOND NUMBER (for a 4 number code) Primary edge is perpendicular to the ○ Primary cutting edge angle axis of the handle. ○ Measured from a line parallel to the Similar to the carpenter's chisel. long axis of the instrument handle in Uses a straight thrust force. clockwise centigrade ○ Angle is expressed in percent of 360 ENAMEL HATCHET degrees Blade is larger and heavier than an ○ e.g. 85 = 85% x 360 degrees = 306 ordinary hatchet, beveled on only one THIRD NUMBER (2nd number of a 3 number side. code) Used for cutting enamel. ○ Blade length in millimeter Has a right and left side. ○ e.g. 8 = 8mm GINGIVAL MARGIN TRIMMER FOURTH NUMBER (3rd number of a 3 Designed to produce proper bevel on number code) the gingival enamel margins. ○ The blade angle Relative to the long Rounding or bevelling of the axio axis of the handle in clockwise pulpal line angle centigrade  OPERATIVE DENTISTRY Similar to the enamel hatchet except Fundamental Rules in the Use of Stationary the blade is curved. Stones: Has a right and left side. 1. Lay the stone on a flat surface. Thin film of light oil should be placed on working surface. II. NON-CUTTING INSTRUMENT e.g. amalgam condensers, mirrors, explorers, probes SHARPENING OF HAND CUTTING INSTRUMENTS Hand cutting must be sharp to be effective. It is required because dull instruments cause : 2. Grasp the instrument firmly (modified pen pain during instrumentation grasp) to prevent rotation or changes in angle. prolonged operating time more difficult to control reduce quality in tooth preparation TYPES: 1. Stationary Sharpening Stones e.g. Oilstones 2. Mechanical Sharpeners e.g. Rx Honing Machine 1. STATIONARY SHARPENING STONES (Oilstones) 3. Use finger rest (ring or little finger) to prevent block or stick of abrasive material rolling and dipping of instrument coarse, medium or fine grit – only the fine grit is suitable for sharpening dental instruments. flat, grooved, cylindrical, and tapered. Types of material: Arkansas stone 4. Use a light stroke to prevent creation of heat ○ Naturally occurring mineral containing and scratching of stone. microcrystalline quartz ○ Preferred material for fine sharpening stones ○ Semi-translucent, white or gray 5. Use different areas of the stone Silicone Carbide (SiC) ○ Widely used as an industrial abrasive. Sharpening of GINGIVAL MARGIN TRIMMER ○ Commonly used material for grinding Palm-and thumb grasp may be used while wheels and sandpapers holding stone in opposite hand to establish ○ Dark color, black or greenish black proper cutting edge angle. ○ Not suitable for final sharpening of dental instruments Sharpening of SPOON EXCAVATOR Aluminum Oxide A - Beginning of stroke. ○ Coarse or medium grit -Speckled tan B - Continuation of pull stroke while rotating or brownish handle in a direction opposite the stroke. ○ Fine grit – white (superior in quality) C - Completion of stroke ○ Water or light oil can be used as lubricant  OPERATIVE DENTISTRY Principles of Sharpening 1. Sharpening instrument only after they have ROTARY EQUIPMENT been cleaned and sterilized HANDPIECE - A device for holding rotary 2. Establish the proper bevel angle before placing instruments, transmitting power to them, and the instrument against the stone, maintain for positioning them intraorally. these angles while sharpening. Low Speed - below 12,000 rpm 3. Use a light stroke or pressure against the used for cleaning teeth, stone to minimize friction heat. occasional caries excavation, 4. Use a rest or guide whenever possible. finishing and polishing 5. Remove as little metal from the blade. procedure 6. Lightly hone the unbeveled side of the blade Medium or Intermediate – 12,000 – after sharpening 200,000 rpm 7. Resterilize the instrument High or Ultra Speed – above 200,000 8. Keep the sharpening stone clean and free of rpm metal cuttings tooth preparation and removal of old restorations Mechanical Sharpness Types of Rotary Tool this instrument moves a hone in a 1. Burs reciprocating motion at slow speed while the 2. Stones instrument is held in proper angulation interchangeable hones of different shapes and Classification of Dental burs coarseness 1. Steel 2. Tungsten Carbide 3. Diamond Classification according to Shape of Head Round Bur Inverted Bur Straight Bur Tapered Bur > CLASSIFICATION OF DENTAL BURS CARBIDE BURS ○ operates most efficiently at high speed Sharpness Test ○ has the ability to retain its sharp edge Sharpness of an instrument can be tested by over repeated usage lightly resting the cutting edge of the instrument on a hard plastic surface. Disadvantages sharp – instrument will dig into the plastic ○ brittle, has tendency to fracture under dull – instrument will slide pressure ○ side pressure must be avoided Sterilization ○ fracture can be avoided if the bur is Implies the complete destruction of all guided into the preparation microbial life including spores and resistant STEEL BURS viruses. ○ effective in cutting at low speed on Dental Instrument are sterilized by he ff: dense, hard tissue ○ Autoclaving (steam under pressure) ○ plain steel bur under low speed ○ Dry Heat generates ○ Glass Bead ○ heat in the tissues of the tooth = ○ Ultraviolet light discomfort to patient ○ Cold sterilization ○ used most frequently for laboratory Sterilizing carbon steel instruments (by Cold work disinfection, boiling, or autoclave) causes discoloration, rust, and corrosion. Methods to Prevent or Minimize Problems ROUND = ¼ , ½ , 2, 4, 6 – 12 1. electroplate the instrument ○ for initial penetration of tooth structure, 2. use of rust inhibitors gross caries removal and placement of 3. remove the instruments promptly at the end of retentive areas the recommended sterilizing period. INVERTED CONE = 33 ¼ , 33 ½, 34, 35, 37 - 40 Dry heat sterilizers do not rust and corrode carbon ○ for placement of retentive areas or steel instruments, but high heat may reduce the points or flattening of floors hardness of the alloy, this reduces the ability of the ○ not to be used for straight wall instrument to retain a sharp cutting edge. formation or caries removal  OPERATIVE DENTISTRY CYLINDRICAL PLAIN (non-dentate) The following must be considered in evaluating FISSURE = 55, 56, 57,58 – 61 Pulpal Reaction: ○ used for gross reduction of teeth, refinement of straight walls , and 1. Protective Mechanisms of the Pulp preparation of proximal boxes 2. Age of the Patient CYLINDRICAL CROSSCUT FISSURE 3. Type of Cutting Instruments (dentate) = 556, 557, 558,559, 560 – 563 Diamond burs that are dull results to ○ same functions, but cut faster, last heat production. Diamond burs longer, and generate less heat generate more heat when cutting at ○ do not leave a smooth surface at the increased speed w/o coolants. cutting interface 4. Methods of Application TAPERED PLAIN FISSURE = 168 TO 173 low speed → high pressure area of ○ same as cylindrical fissure burs intermittent cutting was one method of ○ excellent in preparing in refining walls controlling frictional heat. for cast gold restorations Increased speed → decreased TAPERED CROSSCUT FISSURE = 699, 700, pressure, intermittent cutting & use of 701, 702, 703 coolant. ○ same functions as tapered plain 5. Coolants fissure, but leaves a rough surface the most common type of coolants ○ Air ○ Water ○ Air-water spray 6. Air Evidence of less heat is produced during cutting at high speed. Air coolant should only be used when visibility is a problem. 7. Water Use of warm water is effective in controlling temperature increases. Disadvantage visibility is somewhat hampered & the water must be removed constantly. 8. Air and Water Spray Most popular type of coolant. HEAD Advantages ○ working part of the instrument Visibility is not a problem, less water ○ cutting or points that perform the required desired shaping of tooth structure. Properly directed atomized spray ○ All rotary cutting instruments that have keeps the operating site & cutting bladed cutting heads called a BUR instruments free of debris (Dental Bur) Air/Water spray is superior to the water spray for subgingival margination.( SHANK helps the gingival crevice open for ○ -the part that fits into the handpiece better vision) ○ -accepts the rotary motion from the handpiece How to minimize Trauma During Cavity ○ -provides a bearing surface to control Preparation: the 1. Combination of Air/Water Spray ○ alignment and concentricity of the 2. Use of small sharp instruments instrument 3. High speed and light intermittent application. NECK ○ intermediate portion of the instrument Pulp Response: that connects the head to the shank. Reaction of pulp will depend on the causitive ○ transmit rotational and translational agents & proximity to the pulp. forces to the head. Mild irritation → reparative dentin will form beneath the damaged tissues. Bur Classification System Severe injury → pulp inflammation 1. SHAPES refers to the contour or silhouette of the head basic head shape; round, inverted cone, pear, straight fissure, and tapered fissure 2. SIZES The number designating the bur size also served as a code for head design. Numerical Code - described using an arbitrary numerical code for head size and shape. Pulp Reaction to Rotary Cutting Instruments Heat generated by the cutting instruments during removal of tooth structures has been generally accepted as a major cause of pulp injury.