Dental Instruments PDF

# Instruments (part 2) ## Cutting Instrument Classified to → 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...

# Instruments (part 2) ## Cutting Instrument Classified to → 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 grasp instrument 6. Shank → part connect working end to handle 7. Blade/workingend/cutting edge → part which designed for specific function * (If instrument is Non-cutting this part is called nib/face/non cuttingend/point) * Ex: end of mirror/probe/burnisher is called nib/face/point as it is Non-cutting /Non-working #### Examples (excavator, chisels are very important) 1. Excavator - remove soft dentin caries, debris, decay from the tooth 2. Hatchet, Hoe excavator → smooth floor and walls of the tooth preparation 3. Chisel - smooth enamel margin, forms sharp line and point angles and place retention grooves * ✓ Smoothening of finish line for fixed restoration also preparation wall so use side cutting and end cutting chisel 4. Gingival margin trimmer → place 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 ..............) 2. Manner of their use/movement during operation (push, pull) 3. Form of its working part (hatchet, Hoe excavator ...........) 4. Number of angels in the shank (straight (no angel) -mono angel -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 comprised air. * ✓ Similar to that used for dental implant. * ✓ Also need a special type of hand piece "reduction speed". 2. **Compressed air (air turbine)(pneumatic)** → speed depend on pressure that 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 hold the rotary cutting instrument transmit power to them then inserted intraoral * **Rotary speed range** 1. Low speed (below 12000 rpm) → may be straight or contra angle 2. Medium speed (12000:200000 rpm) 3. High speed /ultrahigh (above 200000 rpm) → contra angle * **Shape of hand piece** * ✓ For low speed hand piece may be 1. Straight hand peace 2. Contra-angel hand piece ### Low speed(Mostly of low speed is latch type) #### Disadvantage 1. Ineffective 2. Time consuming 3. Require relative heavy force during its usage so more heat generation also increase 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 preparation for restoration and remove old restoration 2. Crown preparation for fixed prosthesis ## 3. Laser hand piece ### Definition * Device which produce very high intensity light instead of rotary instrument * **Design** * Laser is conducted through a fiber-optic cable. * Resembles a standard hand piece. * Maintains a water-coolant system. * Laser effect depends on the power of the beam & extent to which 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 ### Advantage 1. Usually painless and not require anesthesia 2. Proceed with procedure faster ### Disadvantage * Not used on teeth with existing restoration (ex: not used to remove old amalgam as amalgam is more harder) ## 4. Air abrasion hand piece ### Design * Small version of a sandblaster. * Produces a high-pressure delivery of aluminum oxide particles through a small probe. * Ex: air flow device EMS ### Uses 1. Prepare teeth to apply pit and fissure sealant. 2. Remove external stains for polishing of the tooth (it has more benefits than ordinary polishing as not remove external layer of enamel)....the main use (ordinary polishing remove outer layer of enamel) 3. Make surface treatment of crown or veneer for cementation (Technician mostly make surface treatment to crowns, veneer befor cementation) ## Cutting tools The rotary tools used in removing tooth structure may be classified 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 * a. Stones * b. Dises ### Design #### Shank * Part fit in hand piece and accept 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 connect head to shank * ✓ Transmit rotational force to the head #### Head * ✓ Working part/cutting edge which perform 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. Tungesten carbide 3. Diamond ships 4. Sand #### According to head size #### According to head shape ## Abrasive instrument * ✓ Small angular particles of hard substance held in a matrix of softer material 1. Diamond stones 2. Dises ### 1. Diamond stones #### Advantage 1. Long life 2. More effective in cutting enamel and dentin #### Classification #### According to size of diamond particles/color coded * Super(very)-fine → 38-44 µm * Fine → 60-74 µm * Medium → 88-125 µm * Coarse → 125-150 μm * (Also there is extra coarse-ultra fine) * (Sizes of diamond particles is color coded and color differ from manufacturer to another) * (white and violet color indicate more fine particles) #### According to function 1. Reducer (depth cutter): determine amount of teeth reduction for veneers or used with minimal preparation/reduction (for 0.2mm reduction need 1.4mm depth cutter) 2. Cutter:ex: trans-metal bur for crown cutter to cut existing crown for replacement 3. Finishing: ex: end cutting stone for finishing of finish line, but care to avoid undercut * (Its diameter must be coincide with diameter of stone that prepare the finish line) 4. Guidance stone : ex: Used for finishing and not increase amount of tooth reduction 5. Polishing stone for smoothening preparation ### Uses #### According to head shape ##### Wheel stone 1. Reduction of the incisal surface 2. Reduction of occlusal planes of cusps of posterior teeth 3. Reduction of lingual or palatal fossa of anterior teeth ## Fine taper/needle (TC" taper cylinder) * ✓ Open contact area during preparation ### Tinker stone * ✓ Used to perform shoulder with bevel finish line for PFM restoration (bevel may be made by gingival margin trimmer) ### Oval or flame shaped or foot ball * For preparation of palatal and lingual surface/fossa of anterior teeth (preferred for palatal fossa) ### Barrel Pear shaped stone * ✓ For preparation of occlusal surface of premolars, molars (not give well/good preparation) ### Fissure stone * a. Tapered with round end (TR)used for chamfer finish line with full metal restoration * b. Tapered with flat end (TF) used for shoulder finish line for all ceramic full coverage * c. Cylinder stone (long/short) used to do grooves for partial coverage restoration * d. Butt stone - Used to perform vertical preparation (BOPT "biologically oriented preparation technique") this stone has safe end cutting (prevent both finish line and gingival injury), used with vertical preparation(Verti prep), indicated with endodontic treated badly decayed tooth, may be edgeless or feather edge finish line and may extend to minor cut junctional epithelium that will heal and not extend to connective tissue * (due to if make horizontal preparation so increase amount of tooth reduction which not compatible with badly decayed tooth) ## 2. Dises * ✓ Abrasive rotary instruments used for proximal slicing or reduction * ✓ Used with slow and conventional speed. * Supplied either mounted or demounted. * Discs with long shank used with straight hand piece for extra oral finishing of prosthesis (denture .............) ### Classification #### According to material 1. Carborundum 2. Diamond 3. Metal * (Used for proximal slicing creating space for orthodontic treatment) 4. Sand paper(used for smoothening restoration) #### According to size/diameter (mcg) 1. Small(3/8 inch) 2. Medium (5/8 inch) 3. Large (7/8 inch) #### According to shape 1. Flat shaped disc 2. Cup shaped disc #### According to the side of abrasive material 1. Single (safe) sided abrasives are on one side so prevent injury to adjacent teeth, and used to open contact area, make reduction to one tooth 2. Double sided abrasives are in both sides when adjacent teeth are missed ## Accessory instrument * ✓ Used with adjusting temporary crowns * ✓ For mixing of cement 1. Scissors 2. Spatula cement 3. Articulator * ✓ Ex: semi-adjustable articulator, face bow for full mouth rehabilitation ### 4. Impression tray * May be Stock tray Custom trav * Quadrant tray used for one half of the arch * Section tray used for segment of the arch (anterior segment) * Full arch tray cover the entire arch * ❖ May be * ▼Y * YYYY * a. Perforated-holes in the tray create mechanical lock to hold the material in place * b. Non perforated/smooth tray →interior surface of the tray is painted or sprayed with adhesive to hold the elastic impression material * • Stainless steel tray is preferred than Aluminum or plastic tray due to is more stiff and rigid tray (Aluminum can be used for implant impression) ### Types of stock tray may be: 1. Plastic perforated tray used for preliminary and final impression 2. Metal perforated tray→usually for preliminary impression 3. Metal water.coolant tray with water cooling system used with reversible hydrocolloid impression (agar-agar material) 4. Bite tray/Dual arch has mesh and used for making impression of both arches in the same time also record occlusion (may be quadrant tray or full arch tray),not accurate impression for both arch together ## 5. Retraction cord applicator * For application of retraction cord befor making an impression to allow recording of sub gingival finish line * May be serrated or Non serrated ## 6. Crown removal automatic (act by spring like action) ## 7. Crown removal manual ## 8. Automatic crown removal (act by gun) * N.B * Crown removal not used with periodontally affected teeth due to causing extraction of teeth so can use cutter for cutting crown ## 9. Scanners (Digital impression techniques): * ✓ Either intraoral scanners (direct digitalization) or extra-oral scanners (indirect digitalization). ### Intraoral scanner (IOS) * Capture the shape and size of the dental arches or the position of dental implants using scan body) through the emission of a light beam. They project a light source onto the dental arches, tooth surface or implant scan bodies through high-resolution cameras also capture emergence profile of gingival around implant * ✓ The information collected by these imaging sensors is processed by powerful scanning software that reconstructs the virtual 3D models of patients, saved on computer without making a plaster model.