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Edit Comment Close Premium member Presentation Transcript Speed in dentistry : Speed in dentistry Dr . P. Baskar PG student Dept of conservative dentistry and endodontics TNGDC. Chennai CONTENTS : CONTENTS Introduction History& Evolution Classification Parts of Handpiece Basic criteria used for evaluating handpiece Mechanism Methods for holding the rotary instruments in handpiece Hose Connectors & Coolant system Power source for handpiece Improvements in designs Safety precaution& lubrication Sterilization& Asepsis Conclusion INTRODUCTION : INTRODUCTION The term SPEED in dentistry has greater importance in all the treatment procedures . SPEED refers to revolution per minute. certain speedy devices like handpiece ultrasonic , sonic instruments plays greater role in dentistry . What is an handpiece ? : What is an handpiece ? A hand piece is a - device for holding rotating instruments, transmitting power to them and for positioning them intra orally. Slide 6: The dental hand piece is used in operative and restorative dentistry to cut tooth structure for various types of preparations. to remove old metal restorations to polish teeth and finish various types of restorative materials. The hand piece may also be used in oral surgery and for implant procedure. Slide 7: Most development of methods for preparing teeth has occurred within the last 100 years .effective equipment for removal and preparation of enamel has been available since 1947. speeds of 10,000 rpm were first used along with newly marketed carbide burs and diamond instruments. Since 1953 continued improvements have results in equipment that is efficient as well as sterlizable. HISTORY / EVOULTION : HISTORY / EVOULTION 1868 – Dr.Jonathan Taft in his text book of operative dentistry. Cutting procedures on tooth enamel and dentin were carried out using thick, bulky chisels and excavators. The first rotary instruments used for cutting tooth tissue were actually drill or bur head that could be twisted in the fingers, for a cutting action. He described them as “bur drills”. Slide 9: One of the refinements of these bur drills was scrantons drill. This could be rotated in either direction to achieve its cutting action. The next modification was drill ring. Slide 10: 1871 – Morrison modified and adapted the dental foot engine from the singer sewing machine. For the first time, cutting procedures were carried out with a power source. 1883 – electric dental engine linked to the hand piece by a flexible cable arm was introduced. 1910 – belt driven hand piece was introduced 1950 – ball bearing hand piece was introduced Slide 11: 1953 – nelson introduced, first fluid turbine type hand piece with speed of 50,000 rpm. 1954 – air driven hand piece were developed with possible speed of 150,000 rpm. 1957 – rotational speed was increased to 300,000 rpm 1960’s – introduction of air bearing hand piece with speed of 500,000 rpm. 1963 – ultrasonic method of tooth tissue removal with vibrating frequency ranging from 15,000 - 30,000 cycles / second. How do we classify handpiece? : How do we classify handpiece? Dental hand pieces classified according to driving mechanism Gear driven hand piece Water driven hand piece Belt driven hand piece Air driven hand piece Slide 16: Depending upon angulations Straight Contra angled Right angled Each is designed for a specific range of functions Slide 17: Straight hand piece the straight hand piece may also be used with a straight shank. Rotary instrument on anterior teeth or where a direct approach to teeth is possible. Slide 18: Contra angled hand piece is designed to provide the operator with greater accessibility to the oral cavity during operative dentistry. Right angle hand piece in which the head of the hand piece forms a 90o angle to the shank. The most popular right angle hand piece is the prophy angle. DEPENDING ON SPEED : DEPENDING ON SPEED Speed is defined as the number of revolution per minute (RPM) or the number of times a rotating instrument, such as a bur, will make a full turn during a minute. The higher the rpm, the faster the speed of hand piece. Low or slow speed - below 12,000 rpm Medium or intermediate speed - 12,000 to 200,000 rpm High or ultra speeds - above 200,00 rpm Slide 20: AIROTOR (or air turbine) speed 250,000 – 500,000 rpm gives the highest speeds but with rather less torque than low speed hand piece. The high speeds are achieved by a small air driven rotor or turbine mounted in bearings in the head of a airotor hand piece. The hand piece always contains a system which directs water spray at the cutting head of the bur and often also contains a fiber – optic light. LOW SPEED HAND PIECE : LOW SPEED HAND PIECE Speed ranges from 10,000 to 30,000 rotations per minute (rpm) Low speed hand piece Straight Contra angle The speed of these hand piece is less but the torque is greater. Low speed hand pieces can be rotated clockwise or anticlockwise, where as airotor only rotates clockwise. SELECTION OF LOW SPEED HAND PIECE : SELECTION OF LOW SPEED HAND PIECE Slide 23: 1:1 Ratio contra angle handpiece used for most procedures. Latch grip burs are used. Commonly identified with the blue color on the shank of the handpiece and a blue dot on the head. Speed range 4000-40000 rpm 1:4 Speed increasing handpiece. Commonly identified with the red band. Speed 16000-160000 rpm Slide 24: 7:1 Ratio speed reducing handpiece used for drilling pin holes and other procedures where slow speed is indicated.Commonly identified with the green band.Speed range 550-5500 rpm Slide 25: USES Low or slow speed cleaning teeth, occasionally caries excavation finishing and polishing procedures. ADVANTAGES – At low speeds, tactile sensation is better and there is generally less chances for over heating cut surfaces. Slide 26: DISADVANTAGES Cutting is ineffective, more time consuming and produces vibrations of low frequency and high amplitude. Heat and vibrations are the main sources of patient discomfort. HIGH SPEED HANDPIECE : HIGH SPEED HANDPIECE Operates at speeds up to 450,000 rpM Tooth preparation Removing old restoration. with high speed cutting instruments removal of tooth structure is faster with less pressure, vibration and heat production. Patients are generally less apprehensive because annoying vibrations and operating time are decreased Variable control to regulate the speed makes the hand piece more versatile. This allows the operator to easily obtain the optimal speed for the size and type of rotating instrument at any stage of a specific operation. PARTS OF THE DENTAL HAND PIECE : PARTS OF THE DENTAL HAND PIECE The basic parts of a dental hand piece include the following Head – the head is the end of the hand piece that holds the rotary instruments,such as burs mandrels, polishing stones and alike. Shank – the shank is the handle portion of the hand piece Connecting end – The connecting end is where the hand piece attaches to the power source of the motor or unit. MECHANISMS : MECHANISMS Air turbine BASIC CRITERIA SHOULD BE USED IN EVUALTING HAND PIECES : BASIC CRITERIA SHOULD BE USED IN EVUALTING HAND PIECES Friction Torque Vibration FRICTION : FRICTION Will occur in the moving parts of a hand piece especially the turbine. If the heat from friction is not prevented or counteracted, the hand piece will be unsuitable for dental use. For this reason bearings are used: ball bearings, needle bearings, glass and resin bearings etc. TORQUE : TORQUE Is the ability of hand piece to withstand lateral pressure on the revolving tool without decreasing the speed or its cutting efficiency Torque Depends on Type of bearing used Amount of energy applied to the hand piece. VIBRATION : VIBRATION As vibration is a very deleterious aspect of rotary instruments so the care to be taken not to introduce it unnecessarily. Excessive wear of the turbine bearings will cause eccentric running which creates substantial vibration. For Better cutting efficiency the ideal requirements are : For Better cutting efficiency the ideal requirements are Greater rpm Smaller cutting tool Less force effective lubrication Pressure : Pressure Pressure is related to force and surface area For low speed instrument it requires 2- 5 pounds For high speed instrument less force 1 pound For ultra speed still less force 1-4 ounces is needed Heat production : Heat production Is directly proportional to Pressure RPM Area of the tooth permanent damage of pulp may result when the temperature of 130 degree F Structural changes to high speed instrumentation for cavity : Structural changes to high speed instrumentation for cavity Mechanical distortion of dentin Exudation of fluid from the prepared surface due to the heat generated during preparation Marked differences in osmotic gradients chemotaxixs form toxic agents of dentinal surface build up intrapulpal pressure due to inflammation Physiologic reactions to high speed instrumentation in cavity and crown preparation : Physiologic reactions to high speed instrumentation in cavity and crown preparation Increase in blood flow in cavity preparation Blood flow is decreased with high speed bur without water spray. Blood flow depends on the thickness of the dentin . If 1mm of dentin remained there would be 90 % reduction in the blood flow after one hour. Slide 39: Micro motors In case of micro motors, in addition to the turbine, it is necessary to have a slower speed motor to accomplish tasks such as Soft caries removal Finishing and polishing etc Speed range – 500 – 100,000 rpm : According to mechanism of working Air driven Electric driven Air motors - mechanism Rotary vane principle Swash plate principle ELECTRIC DRIVEN : ELECTRIC DRIVEN Most are d.c. motors and are designed with an armature sitting within a permanent magnet assembly The performance depends upon design and power of the magnetic field design and number of armature coils. By varying the distance from the magnets to the rotating armature, the speed of the motor can be altered. Slide 42: This feature is incorporated into some micro motors to give two speed ranges selectable at the motor. More the armature coils, the smoother and less jerky the operation of the motors. Air-Abrasion Handpiece : Air-Abrasion Handpiece Design Small version of a sandblaster. Produces a high‑pressure delivery of aluminum oxide particlesa small probe. Air-Abrasion Handpiece : Air-Abrasion Handpiece Uses Prepares teeth for sealants. Removes external stains. Class I through class VI preparations. Endodontic access. Crown margins. Prepares a tooth surface for the cementation of a cast restoration, such as a crown or veneer. Methods for holding Rotary Instrument in hand piece : Methods for holding Rotary Instrument in hand piece The Rotary Instruments (Bur) may be held in place by tightening a bur-rod knob at the end of the hand piece or by using a special bur tool provided by the manufacturer. Newer hand pieces may have either a button or release lever that is used to secure and release the Rotary Instrument Slide 46: Inside the head of the hand piece is a small metal cylinder called a chuck. The chuck is designed to hold the shank portion of the Rotary Instrument in the hand piece. Rotary Instruments such as burs, stone and mandrels are inserted into the chuck and are held in position by either a Latch type system Friction-grip type Slide 47: Latch type hand piece uses a special notched shank rotary instrument. The rotary instrument is inserted into the chuck and is held in the hand piece by a movable latch Friction grip: The friction grip rotary instruments system are used with air turbine hand piece. COOLANT SPRAY SYSTEMS : COOLANT SPRAY SYSTEMS A considerable heat is generated when an air turbine is cutting teeth. This heat has to be removed rapidly from the cutting site. All current hand piece have provision for an air-water spray from closely positioned air and water jets to be directed onto the rotary cutting for cooling and clearance of debris. Slide 49: Some hand piece have tubes carrying water and air separately or even a single water / air nozzle combination. Some hand piece have a single nozzle and some hand piece have multiple water – air nozzles which equally spaced around the head. Power source for the hand piece : Power source for the hand piece A source of energy (power) is needed to operate all dental hand piece. The flow of power may be activated by the use of a foot control or a Rheostat (a device used to regulate an electric current without interrupting the circuit of flow). A Rheostat is used with the belt driven hand piece and is operated by electricity. A foot control is used with the air turbine hand piece and is operated by compressed air. IMPROVEMENTS IN DESIGN : IMPROVEMENTS IN DESIGN FIBEROPTIC SYSTEM OF HAND PIECE Fiber optic refers to a light system that uses special glass fibers called optical bundles to carry a source of light to the dental piece. The light source is – tungsten halogen bulb Fiber optic systems can be used with Slow – speed hand piece High – speed hand piece Slide 53: This provides an additional source of light in addition to the dental light from the unit. Two fiber optic system are available One system carries the light (via) optical bundle to the hand piece from a remote source, such as a control box. Second system, a bulb is attached to rear of the hand piece, and the light is carried through the optical bundles within the tubing of the hand piece and from the dental unit. Slide 54: ADVANTAGE Improved visibility for operator during tooth preparation DISADVANTAGES Increased hand piece mass in case of hand piece loaded with the bulb with hand piece running light source is cooled by the air flow, but if lamp is operated for long period after the air flow is stopped, then it may over heat. Reduced flexibility of the hose SAFETY PRECAUTIONS : SAFETY PRECAUTIONS Maximum effectiveness with minimum damage to the hand piece can be accomplished by using the following precautions Improper handling of hand piece, use of incorrect bur, improper maintaining of a bur and extended use of noisy cartridge must be avoided. Do not use a bent, damaged or non concentric burs. Slide 56: Mount the bur into chuck correctly as instructed by the manufacture Do not run the hand piece without a bur or bur loosely mounted Always securely mount a bur in the chuck, even while it is not in use. In screw cartridge Do not tighten the chuck without a bur in it. ¼ to ½ counter wise turn to a chuck is sufficient to remove a bur. Excessive turning may cause the chuck to bind into head cap. Slide 57: Ultra push type cartridge (Prevention of button heating). Do not press the push button during rotation. Contact with cheek tissue may cause the push button to depress and burn to patients may occur. Sterilize the hand piece either a stem autoclave or chemical vapour sterilizer. Do not dry heat. CLEANING OF HAND PIECE : CLEANING OF HAND PIECE Do not use wire brush to clean the hand piece sheath. Wipe it clean with alcohol immersed cloth or cotton swab Do not clean in an ultrasonic bath, boiling water nor chemicals. To clean the turbine cartridge - spray a lubricant into the drive air tube of the hand piece LUBRICATION : LUBRICATION Adequate lubrication to the bearings is a must for extended bearing life. Spray a lubricant into the drive air tube of the hand piece until a good amount of it comes out of the head. Run for a while to drive out excess oil. Repeat until dirty oil does not come out of the head or Supply 2 – 3 drops of oil into the drive air tube of hand piece and run for a while. STERILIZATION AND ASEPSIS : STERILIZATION AND ASEPSIS The hand piece of the rotary instruments are used in the mouth must be cleaned and sterilized for reuse. All such items are readily sterilized by three or more methods of sterilization. Autoclave Chemical vapour pressure sterilization Ethylene oxide (Etox) gas. STEAM STERILIZATION OF HAND PIECE : STEAM STERILIZATION OF HAND PIECE Autoclave sterilization of hand pieces is one of the most rapid method. AUTOCLAVING PROCEDURE: If proper cleaning and lubricating is preformed as prescribed by the manufacturer, good utility is obtainable with regular autoclaving. Insert into a sterilization bag and seal it Autoclave at : 121o for 20 min or 132o for 15 min OTHER METHODS : OTHER METHODS Chemical vapour pressure sterilization Ethylene oxide (Etox) gas. Rotary contra-angle handpiece in Endodontics : Rotary contra-angle handpiece in Endodontics Medidenta/ micromega MM324 reduction gear handpiece Aseptico electric motor handpiece The Quantec ETM electric torque control motor Myco/union broach sprint EDM electronic digital handpiece Speed vary from 300 rpm to 2000o rpm Rotary niti instruments speed : Rotary niti instruments speed Morita trio Auto –ZX : Morita trio Auto –ZX cordless , battery powered endodontic , slow speed handpiece with a built in apex locator . Three automatic function starts automatically when the file enters the canal and stops when the file removed . If too much pressure is applied the handpiece stops automatically and reverses the rotation It also stops and reverses rotation when the file reaches the apical stop ,which determined by the built in apex locator. Reciprocating handpiece : Reciprocating handpiece Accepts only latch type of instruments The quarter turn motion deliveres 3,000 times per minute Kerr , M4 handpiece which has 30 degree reciprocating motion Endo gripper handpiece has 10:1 gear ratio and a 45 degree turning motion. Ultra sonic handpiece : Ultra sonic handpiece a system has an energy source 20 to 25 KH .it activates endodontic file, resulting in three dimensional activation of the file in the surrounding medium . Slide 68: Design of ultrasonic handpiece Attached to the dental unit. Powered by electricity. Primarily used for prophylaxis appointments. Attachments are similar in appearance to scaling instruments. Delivers a pulsating spray of water. Uses of the Ultrasonic Handpiece : Uses of the Ultrasonic Handpiece Remove calculus Remove stain Remove bonding materials from tooth surface after orthodontic appliances are removed Remove cement after orthodontic bands are removed Sonic handpiece : Sonic handpiece The sonic handpiece available today is micro mega 1500 or 1400 sonic air endo system The air pressure may be varied with an adjustable ring on the handpiece to give an oscillatory range of 1500 to 3000 cycles per second . CONCLUSION : CONCLUSION The extensive knowledge of the different types of hand piece available, acurate speed, safety precautions, proper sterilization technique are essential for a dentist to do his work successfully. References : References Operative dentistry-Sturdevant 4th edition Operative dentistry-Charbenau 3rd edition Operative dentistry-Marzouk Operative dentistry-Vimal k.Sikri Practical Guide to technology in dentistry-Nicolas Pickards manual of operative dentistry-E.A.M Kidd & Smith Slide 73: THANK YOU You do not have the permission to view this presentation. In order to view it, please contact the author of the presentation.