Dental Instruments PDF

eq ar d T Dr. Mohamed Tareq Fahmi e am Lecturer of fixed prosthodontics oh M Dental Instruments In Fixed Prosthodontics work we use...

eq ar d T Dr. Mohamed Tareq Fahmi e am Lecturer of fixed prosthodontics oh M Dental Instruments In Fixed Prosthodontics work we use instruments to cut and reduce enamel eq ar d T e am oh M  e q e q ar a r d T d T e e q am am re o h oh T a M M e d am o h Dental Instruments M  eq Dental Instrument: refers to a tool ar T or a device used for speci c type d of work or procedure. e m Cu ng Instruments: are used to cut, le, grind, plane, or smoothen ha o dental structures M tti fi fi Cutting instruments Classified according to their mode of ar cutting into: d T Hand cutting instrument e Powered (rotary) cutting instruments am Laser equipments Other equipments oh M  Hand instruments r Cutting Instruments a. Excavators ( hatchets, hoes, angle formers and spoons). Ta b. Chisels (straight chisel, curved chisel, enamel hatchet and gingival ed marginal trimmers) am h c. Other cutting instruments may be subdivided as o knives, files, scalers and carvers Non-cutting Instruments (amalgam condensers, mirrors, probes and explorers) M  eq ar d T e am Hand Cutting Instruments oh M  eq ar d T Hand Non-Cutting Instruments e am oh M  Hand Instruments Hand powered Light in weight ar Material of d T a. Carbon steel e b. Stainless steel am c. Carbide oh M  Instrument Design A. Blade B. Shank C. Hand  eq ar d T e Rotary Cutting am h Instruments o M  eq ar The rotary cutting d T instruments are held e and operated by am removable shank oh M called (Hand piece)  Hand pieces are classified as : eq According to the shape: ar a. Straight Hand piece d T e b. Contra Angle hand piece am h  According to the power source: eq r A- Air turbine Ta B- Electric motor ed am oh Rotary Speed Ranges The rotational speed of an instrument is measured in a revolution per minute (rpm) Three speed ranges are recognized: d T Low or slow speeds (below 12.000 rpm) Medium or intermediate speeds (12.000 to 200.000 rpm)e High or ultrahigh speeds (above 200.000 rpm ) am oh M Rotary cutting Instruments Design Common design : A. Head B. Neck C. Shank Shank Design A. Straight shank B. Latch-type shank C. Grip-type shank Head Design ar According to the mode of cutting it is classified into: d T e A: Abrasive instruments am B: Dental burs oh M Dental burs ar Cutting instruments that have bladed cutting heads d T e Material of construction : am A: steel oh M B: carbide Classification Size: Number giving to the head diameter in tenth of millimeter ar Shape: d T e m Round Inverted cone ha o Taper fissure End cutting M Abrasive instruments ar small, angular particles of a hard substance held in d T a matrix of softer material e am Abrasive instrument classified into : A: Diamond instruments oh B: Other abrasives M  eq Diamond instrument ar Consists of three parts: d T Metal blank e Powder diamond abrasive Metallic bonding material am oh M Classification size and shape : A. Rounded end wheel B. Flame shape C. Fine taper D. Taper stone with flat end E. Taper stone with round ended  eq ar d T e Other Abrasive Instruments am oh M Other abrasive instruments Molded abrasive instruments pressing or molding a uniform mixture of abrasive particles and matrix around roughened end of the shank According to the matrix rigid polymer or ceramic flexible rubber Coated abrasive instruments : Layer of thin abrasive cemented to flexible backing Dental rotary instruments are supplied in two categories: Mounted type : ar Supplied with their mandrel firmly attached to the working d T points. e Demounted type: am These are mounted to shank oh (mandrel), which carries a variety of interchangeable M demounted rotary points Abrasive vs Burs Mechanism of cutting Abrasives: ar Abrading or wearing d T Burs: e Shearing am Cutting primary from the sides of the instrument oh M Abrasive vs Burs Cutting efficiency Diamonds : ar More efficient but rough surfaces d T e and irregular finish lines Carbide Burs: am More slowly but smooth finish lines oh M Laser equipment eq Laser : ar Are devices that produce d T beams of very high intensity e light am Uses : oh Treatment of soft tissue Modification of hard tooth structure M Abrasive equipment Hard tooth structures are removed by rapid continuous air driven abrasive action of aluminum oxide Clinical problems : No tactile sense Determination of cutting progress eq Interfere visibility Control inhalation ar Uses : d T Stain removal e De-pridment of pit and fissure prior to sealing am Micro-mechanical roughening oh M Thank you r Ta ed am oh M