Dental Instruments PDF

# Instruments (part 2) ## Cutting Instrument Classified according to whether hand or mechanical force or power 1. Hand Cutting Instrument 2. Powered Rotary Cutting Instrument 3. Laser 4. Air Abrasion ### 1. Hand Cutting Instrument #### Manufactured From: 1. Carbon Steel 2. Stainless Steel 3. C...

# Instruments (part 2) ## Cutting Instrument Classified according to whether hand or mechanical force or power 1. Hand Cutting Instrument 2. Powered Rotary Cutting Instrument 3. Laser 4. Air Abrasion ### 1. Hand Cutting Instrument #### Manufactured From: 1. Carbon Steel 2. Stainless Steel 3. Carbide Steel 4. Other alloys of nickel, cobalt & chromium #### Design 5. **Handle** - Part where operator grasps instrument 6. **Shank** - Part connects working end to handle 7. **Blade/Working end/Cutting Edge** - Part which is designed for specific function (If instrument is Non-cutting this part is called nib/face/non cutting end/point) Ex: End of mirror/probe/burnisher is called nib/face/point as it is non-cutting #### Examples (excavator, chisels are very important) 1. **Excavator** - Removes soft dentin caries, debris, decay from the tooth 2. **Hatchet, Hoe excavator** - Smooths floor and walls of the tooth preparation 3. **Chisel** - Smooths enamel margin, forms sharp line and point angles and place retention grooves - Smooths finish line for fixed restoration, also prepares wall so use side cutting and end cutting chisel 4. **Gingival Margin Trimmer** - Places bevel along the gingival margin of the tooth preparation, also used for making bevel at finish line if needed # G.V Black Classifications for Dental Instrument According to 1. Purpose of its use (excavator, condenser, scaler, etc) 2. Manner of their use/movement during operation (push, pull) 3. Form of its working part (hatchet, Hoe excavator, etc) 4. Number of angles in the shank (straight (no angle) - mono angle - bin angel "two" - triple angel "three" - quaternary angle "four") # 2. Powered Rotary Cutting Instrument ## Definition Part or device that rotates around an axis. In dentistry, rotary instruments are attached to a hand piece. ## Power/Energy Source of Dental Unit 1. **Electric motor driven** (separate or used as part of unit) (expensive) - Stable, steady speed with high torque, so effective high cutting efficiency - More control to speed during preparation, so more accurate smooth preparation, save time - No noise compared to compressed air - Similar to that used for dental implant - Also needs special type of handpiece "reduction speed" 2. **Compressed air (Air turbine) (pneumatic)** - Speed depends on pressure that is done by dentist leg ## Rotary Speed Ranges (Important) 1. Low speed (below 12,000 rpm) 2. Medium speed (12,000-200,000 rpm) 3. High speed (above 200,000 rpm) # Hand Piece - Device holds the rotary cutting instrument, transmits power to them, then is inserted intraoral ## Rotary Speed Range 1. Low speed (below 12,000 rpm) - May be straight or contra angle 2. Medium speed (12,000-200,000 rpm) 3. High speed/ultrahigh (above 200,000 rpm) - Contra angle ## Shape of Hand Piece - For low speed hand piece may be: 1. Straight hand piece 2. Contra-angle hand piece ### Low Speed (Mostly of Low Speed is Latch Type) #### Disadvantage 1. Ineffective 2. Time-consuming 3. Requires relatively heavy force during usage, so more heat generation and an increase in vibration #### Indication 1. Initial production of grooves and pinholes 2. Teeth cleaning and polishing of teeth 3. Deep caries excavation 4. Finishing and polishing of restoration ### High Speed #### Advantage - More faster removal of tooth structure with less vibration and heat production - Better control and greater ease of the operator - Patient is less apprehensive, more comfortable because annoying vibration and operating time decreased - Instrument last longer (not dull early) #### Indication 1. Cavity preparartion for restoration and remove old restoration 2. Crown preparation for fixed prosthesis # 3. Laser Handpiece ## Definition Device which produces very high intensity light instead of rotary instrument. ## Design - Laser is conducted through a fiber-optic cable. - Resembles a standard handpiece. - Contains a water-coolant system. - Laser effect depends on the power of the beam and extent to which the beam is absorbed e.g. CO2 and ND:YAG laser ## Use - There are: 1. Cauterizes soft tissue (Soft tissue laser) (mostly used) 2. Vaporize decayed tooth structure (Hard tissue laser) - Has water coolant system - Usually painless and does not require anesthesia - Procedure with procedure is faster ## Advantage ## Disadvantage - Not used on teeth with existing restoration. (Ex: Not used to remove old amalgam as amalgam is more harder) # 4. Air Abrasion Handpiece ## Design - Small version of a sandblaster. - Produces high-pressure delivery of aluminum oxide particles through a small probe. Ex: Air flow device EMS ## Uses 1. Prepares teeth to apply pit and fissure sealant. 2. Removes external stains for polishing of the tooth (it has more benefits than ordinary polishing as it does not removal the external layer of enamel). ... the main use (ordinary polishing removes the outer layer of enamel). 3. Make surface treatment of crown or veneer for cementation (which is called sand blasting, needs zirconium oxide particles). (Technician mostly make surface treatment to crowns, veneer before cementation). # Cutting Tools - The rotary tools used in removing tooth structure may be classified in to burs and abrasives depending on whether they work by an actual cutting or an abrading process. - Can be divided into: 1. Dental rotary bur 2. Dental rotary abrasives - Stones - Dises ## Design ### Shank - Part fits in hand piece and accepts rotation movement from the hand piece. - May be: 1. Long shank - For straight hand piece 2. Short latch shank - For latch type contra angle (low speed hand piece) 3. Friction grip shank- For high speed hand piece ### Neck - Intermediate part of an instrument that connects head to shank - Transmits rotational force to the head ### Head - Working part/cutting edge which performs the desired shaping of tooth structure ## Characteristics of the Head/Classified ### According to Cutting to: 1. Bladed bur (may be plain or crosscut based on flute design), "cross cut carbide bur is trans metal bur" 2. Abrasives stones ### According to Material of Construction: 1. Carbon steel 2. Tungsten carbide 3. Diamond ships 4. Sand ### According to Head Size ### According to Head Shape