Instruments and Instrumentation Used in Operative Dentistry PDF

INSTRUMENTS AND GENERAL INSTRUMENTATION USED IN OPERATIVE DENTISTRY Learning Objectives • • • • Define and spell the Key Terms. Describe the three parts of a dental hand instrument. Describe the instrument formula designed by G.V. Black. Discuss the theory of placing an instrument in a specific s...

INSTRUMENTS AND GENERAL INSTRUMENTATION USED IN OPERATIVE DENTISTRY Learning Objectives • • • • Define and spell the Key Terms. Describe the three parts of a dental hand instrument. Describe the instrument formula designed by G.V. Black. Discuss the theory of placing an instrument in a specific sequence. • List the examination instruments and their uses. (Cont’d…) Slide 2 Learning Objectives (…Cont’d) • Identify examination instruments. • List the types of hand (manual) cutting instruments and their uses. • Identify hand (manual) cutting instruments. • Reading assignment: STURDEVANT’S Art & Science of operative dentistry 6TH Edition 2013: p 164-169 Slide 3 • In order to perform detailed procedures associated with operative dentistry, the dentist must have a complete knowledge of the purpose, availability and application of the many instruments required. • Few areas in the health sciences require greater technical skill than does operative dentistry. • During each day of clinical experience, the dentist operates on vital tissues within the oral cavity where a millimeter, or a fraction of a millimeter, is a significant dimension. • Skillful application of hand and rotary cutting instruments requires psychomotor skill attained only by intensive training. • Hand cutting instruments are manufactured from two main materials: carbon steel and stainless steel. • The variety and complexity of instruments used in operative dentistry make it necessary to classify them according to their purpose or function. • A useful means of identification is thus provided. • Dr. G.V Black provided a basic Nomenclature for dental instruments although these grouping are not totally inclusive. • Operative dental instruments can be conveniently classified in Six categories according to their use: 1- Cutting Instruments Hand Hatchets Chisels Hoes Excavators Others. Rotary Burs Stones Disks Others. 2-Noncutting Instruments( Condensing Instruments ) Pluggers(condensers) Hand, or Mechanical Amalgam carriers 3-Noncutting Instruments(Plastic Instruments) Carvers Burnishers Spatulas Packing Instruments 4- Finishing and Polishing Instruments Hand Orangewood sticks Polishing points Finishing strips Rotary Finishing Burs Mounted Brushes Mounted Stones Rubber Cups Impregnated disks and wheels 5- Isolation Instruments Rubber dam frame Clamps ,Forceps, Punch Cotton roll holder Saliva ejector 6- Miscellaneous Instruments Mouth Mirrors Explorers Periodontal Probes Scissors Cotton pliers, college tweezers Others Examination Instruments ❖ Mirrors, ❖ Explorers, ❖ Periodontal Probe, ❖ and forceps(pliers) are the basic instruments that will be needed during each appointment for diagnosis /treatment. ❖MIRRORS o In every procedure performed in the mouth, the dentist must have clear and distinct vision of the field. o Wherever possible, the field should be viewed with direct vision. o 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. o It also allows the operator to maintain a body position that will reduce health problems associated with poor posture. o Almost as important as its allowing indirect visualization of obscure areas of the mouth is its function as a reflector of light into the area being examined or treated. ❖ MIRRORS o The mouth mirror can also serve as a retractor of soft tissue (tongue, cheeks, lips) o to aid access and visualization. o Mouth mirrors are usually rounded and come in a variety of sizes ,the most widely used sizes for adults are the No.4 and No.5. o While No.2 is used for children or constricted areas in posterior region of the mouth. ❖ EXPLORERS o Explorers are pointed instruments used to feel tooth surfaces for irregularities and to determine the hardness of exposed dentine. o The explorer that is used most is the shepherds hook, or No.23, explorer. o Another useful shapes are cow horn and No.17 explorers, which provides improved access for exploring interproximal areas. Fig. 34-5 Uses of the mouth mirror. Slide 15 ❖ Periodontal Probes o Are designed to detect the depth of periodontal pockets. o In operative dentistry, they are also used to determine dimension of instruments and of various features of preparation. o There are many designs of periodontal probes; the differences are in the diameters, the position of the millimeter marking. ❖ Pliers or Forceps o Cotton pliers are used for picking up various small items, such as cotton pellets. o Hemostats forceps are useful in operative dentistry . o Articulating paper forceps are designed to carry an inked tape to the mouth to mark the contacts of teeth in opposing arches during closure NOMENCLATURE In establishing a nomenclature for hand instruments, Dr. Black prescribed four classes, similar to a biological classification: Order purpose of instrument Suborder position or manner of use Class form of working end Subclass shape of the shank A hand cutting instrument consists of Three parts: Handle or Shaft Portion of the instrument where the operator grasp Small, medium or large diameter; smooth, knurled, or serrated. Shank :Part of the instrument that attaches the working end to the handle Connecting the shaft and the blade or nib. The shank may be straight, single, double or triple-angled. Blade or Nib Also may be appropriately termed the point or head. This is the functional end of the instrument. It begins at the angle that terminate the shank(last angle if there is more than one) and is the part of the instrument that bears the cutting edge, condenser face, or tine. o Enamel and dentin are difficult to cut and require the generation of substantial force at the tip of the instrument. o Hand instrument must be balance to allow for concentration of force onto the blade without causing rotation of the instrument in the grasp. o This balance is accomplished by designing the angles of the shank so that the cutting edge of the blade lies within the projected diameter of the handle and nearly coincides with the projected axis of the handle. o For optimal anti-rotational design the blade edge must not be off axis by more than (1 to 2 mm) o The functional orientation and length of the blade determines the number of angles necessary in the shank to balance the instrument. o G.V Black classified instruments based on the number of shank angles, as: mon-angle (one), bin-angle (two), or triple-angle(three). o Instruments with longer blades or more complex orientation may require two or three angles in the shank to bring the cutting edge near to the long axis of the handle. Such shanks are termed Contra-angled o o Black developed a system of assigning numeric formulas to instruments. The formulas make use of the metric system, That is, millimeters and tenths of millimeter for instrument dimension. For designating the degree of angulations, centigrade are used. o Centigrades are based on a circle divided into 100 units(Celsius compass) o It as substituted for a 360-degree circle(Astronomical compass) ordinarily used to designate angles In a centigrade circle, so a 90 right angle, according to Celsius Compass is only 25 degree centigrades. o The basic instrument formula consist of three units whose measurements are based upon the metric system: o The first unit of the formula describes the Width of the blade in tenth of a millimeter. o The second unit describes the length of the blade in millimeter. o The third unit describes the angle the blade forms with the axis of the handle. o For instruments in which the cutting edge at the end of the blade is not at right angle to the long axis of the blade, Black designed a four – number formula . o The first number is the width of the blade in tenth of a millimeter. o The second number is the angle(in centigrade) that the primary cutting edge(working end) makes with the axis of the handle. o The third number is the length of the blade in millimeter. o The fourth number is the angle( in centigrade) that the long axis of the blade makes with the handle. o The cutting instruments are used to cut hard or soft tissues of the mouth, they are made in pairs, and, as with the gingival marginal trimmers, most instruments used today are double-ended. o Excavators are used for removal of caries and refinement of internal part of the cavity. o Chisels are used primarily for cutting enamel. ❖ EXCAVATORS o Used for removing softened dentine and temporary fillings. o The blade of the excavator it has different shapes, spoon, disk, or banana shaped blade. o The excavator, has its cutting edge at the end of its blade that is parallel to the handle of the instrument. ❖ HATCHET o Paired bin angle enamel hatchet ,are used for planning or cleaving enamel and dentin wall during cavity preparation. o The blade and cutting edge are on a plane with the long axis of the handle; o the shank has one or more angles. o The cutting edge of the blade of the hatchet will be directed either to the left or right in relation to the handle, and the instrument is usually supplied in a double-ended form. o Therefore, there are left-cutting and right-cutting ends . o CHISELS Chisels are intended primarily for cutting enamel and grouped as: o a- straight , slightly curved (Wedelstaedt chisels), mon-angle or bin-angle chisels. o The cutting edge of a chisel is at right angles to the plane of the instrument. o A bin angle chisel is frequently a double-ended instrument , having one cutting edge medial to or nearer the shaft , and another cutting edge distal to or farther from the shaft . o When the cutting edge is mesial to the shaft, it is termed a”contrabeveled or “reverse beveled” chisel. ❖ Gingival Marginal Trimmer o The GMT is a modified hatchet . o is designed to produce a proper bevel on the gingival enamel margins of proximoocclusal preparation. o GMT, like hatchets and spoons, come in pairs(leftcutting and right-cutting). o Also there are Mesial GMT , and Distal GMT. ❖ Gingival Marginal Trimmer o Two distinct modification of the basic hatchet design are observed. o First , whereas the cutting edge of a hatchet is at a right angle to the axis of the blade, the cutting edge of a G.M.T is at an angle other than a right angle to the axis of the blade. o Second , while the hatchet has a straight blade ,the blade of the G.M.T is curved ❖ Gingival Marginal Trimmer o The G.M.T with the curved blade is a double-plane instrument while the Hatchet is a single-plane instrument. o The curved blade accentuates the lateral scraping ability of the instrument. o All double- plane instruments are lateral cutting instruments.