Dental Instruments PDF

INSTRUMENTS  History Most hand instruments used earlier were with large , heavy handles and inferior metal alloys in the blade ,were difficult to use and ineffective. Many dentists made their own hand instruments.  Instrument parts -Shaft -Shank -Blade Shaft/han...

INSTRUMENTS  History Most hand instruments used earlier were with large , heavy handles and inferior metal alloys in the blade ,were difficult to use and ineffective. Many dentists made their own hand instruments.  Instrument parts -Shaft -Shank -Blade Shaft/handle used as a handle is straight without variations in size.  Shank -It connects the handle to the blade -It is here where any angulations in the instrument can be given.  Blade cutting portion of an instrument. -for non cutting instrument e.g. condensers the part corresponding to the blade is called the nib. -working surface or the end of the nib is known as the face.  Examination instruments -Mouth mirror - Probe (explorer) -Periodontal probes -Tweezer  Mouth mirrors for every procedure in the mouth the dentist must have clear and distinct vision of the field. mirror allows the operator to visualized areas of the mouth that can not be able to see directly (indirect visualization). it reflects the light to some areas to examine or treated and retract soft tissues (tongue, cheeks or lips) to aid access and visualization. -A, Indirect vision -B, Light reflection -C,Retraction -D,Tissue protection  Explorers Explorers are pointed instruments used to feel tooth surfaces for irregularities and to detect the tooth decay and to determine the hardness of exposed dentin.  Periodontal probes -Periodontal probes are designed to detect and measure the depth of periodontal pockets. -In operative dentistry used to determine the dimensions of instruments.  Tweezers -To hold cotton roll -To hold different material -To transfer any material in and out of cavity ROTATING INSTRUMENTS -Hand pieces -Burs  Types of dental handpieces 1- straight handpiece 2-contra-angle handpieces -Low speed contra-angle handpiece -High speed handpiece  straight handpiece In the straight handpiece the long axis of the bur is same as the long axis of the handpiece The straight handpiece is used more frequently for laboratory work. and clinically is used in oral surgery.  contra-angle handpieces The primary handpiece used in the mouth is the contra-angle one.Because of this design bur head lies close to long axis of the handle of handpiece which improve accessibility, visibility and stability of handpiece while working. Low speed contra-angle handpiece have a typical free –running speed range from 500 to 15000 rpm some are able to slow to 200 rpm and others able to achieve speeds of 35000 rpm.  Uses of the low-speed handpiece 1-Removal of soft decay and fine finishing of a cavity preparation. 2-finishing and polishing of restoration. 3-Coronal polishing and removal of stains.  High speed handpiece have a free running speed range greater than 160,000 rpm and some handpiece attain free – running speed up to 500,000 rpm Uses of the high-speed handpiece 1-Remove decay. 2-Removes an old restoration. 3-Reduces the crown portion of the tooth for the preparation of a crown or bridge. 4-Prepares the outline and retention grooves for a new restoration. 5-Sections a tooth during surgery.  Dental Burs A bur is rotary cutting instrument which has a cutting blades on head and is available in various shapes and sizes The most significant advance which has made present day high –speed cutting possible is tungsten carbide bur , which became available in 1947. Tungsten carbide Fissure Bur According to their shape and size -Round -Straight -inverted cone -Tapered fissure -Pear shaped  Round burs -Round in shape -Uses : initial tooth penetration Placement of retention grooves  Straight fissure bur -Elongated cylinder. -amalgm tooth preparation.  inverted cone burs -Have an inverted cone shape. -Uses –in cavity extensions -establishing wall angulations and retention form -flatten the pulpal floors  Tapered fissure bur -To cut cavity preparation -To form angles in walls of cavity preparation. -To place retention grooves in walls of cavity preparation.  Pear shaped burs As name indicates ,shaped loke pears. Mainly used in pedodontics  Cross-cut tapered fissure bur -can also be straight or spiral -uses –same as that as straight fissure burs -mostly used in cutting cavities for inlays  Diamond burs used increasingly in operative dentistry. And they have a greater clinical impact due to long life and effectiveness in cutting enamel and dentin. -White : super fine -yellow: extra fine -Red : fine -Blue : standard -Green : coarse -Black : super coarse  Smart Prep instruments -Medical polymer that has the ability to remove decayed dentine while keeping the healthy dentin. -Its hardness less than healthy dentine while harder than the carious dentin  Advantages -Conservative -Minimal to none disease transfer (because its single use only). -For students to start with first clinical cases.  Disadvantages -Single –patient-use (Expensive) -The bur breaks down when it touches enamel. -Technique sensitive (too much pressure and you will cut the healthy dentine). Amalgam Restorative instrument -Amalgam carrier -Condensers -Carvers -Burnishers  AMALGAM CARRIERS A dental instrument used to pick up a quantity of amalgam and transfer it into a prepared tooth cavity.  Condensers Amalgam condensers are used to compress the amalgam into all areas of the preparation. the working ends of condensers may be any shape , but usually they are round with flat ends.  Carvers carvers are used to shape amalgam and resin composite after they have been placed in tooth preparations  Burnishers Burnishers are used for several functions , the most important function are polishing, shining, shaping ,and may be condensing. Football burnisher Function : -To smooth amalgm after condensing to contour matrix band Acorn Burnisher Function : To smooth amalgam after condensing ,used to creat occlusal anatomy.  T-Ball Burnisher Function : -to smooth amalgam after condensing -to contour matrix -initiate carving and occlusal anatomy  Plastic instruments Plastic filling instruments are so named because they were originally designed to use with plastic restorative materials such as the silicates and acrylic resins. They are currently used to carry and shape tooth-colored restorative materials such as resin composite and GIC restorative materials.  Cement Spatulas A variety of materials in operative dentistry require mixing ,some on glass slab, others on a paper pad. several spatulas are available, and they vary in size and thickness. the large cement spatulas were originally designed for mixing luting cements and smaller spatulas for cavity liners. Finishing and polishing amalgam restoration The finishing and polishing procedures should not be initiated on an amalgam restoration until the amalgam has reached its final set , at least 24 hours after it has been placed and carved.  Finishing Finishing amalgam restorations involves -removing marginal irregularities. -Defining anatomical contours. -Smoothing the surface roughness of the restoration.  Polishing Polishing is performed to obtain a smooth, shiny luster on the surface of the amalgam. Why amalgam restorations should be polished -Prevention of recurrent decay. -Maintenance of periodontal health. -Prevention of occlusal problems. An amalgam restoration is not considered complete until it is polished.