Dental instruments Flashcards
Rotation speed of a high speed
greater than 200,000 rpm
Rotation speed of a low speed
less than 12,000
Connector line of a high speed, how many holes?
- fiberoptic
- drive air
- exhaust
- coolant
Straight connector used for?
extraoral procedures
2 types of friction grip bur heads (theres also a latch type head)
Push button, bur tool type
3 parts of bur
shank, head, neck
Head of bur is usually what type of material
tungsten carbide
Neck and shank of bur are usually what type of material?
stainless steal
what are bladed burs used for
excavating tooth or finishing
The greater the number of blades of a bur the …. the finish
smoother
Bladed instrument are used for what kind of drilling?
intracoronal
Diamond burs are more abrasive so they’re used for… procedures
extracoronal (crown prep)
…. restoration: Dental material placed in a soft state directly in cavity prep to restore contour before it sets hard
direct
… restoration: fabricated outside the oral cavity and then cemented or bonded to tooth
indirect
Two types of handpieces
- air driven
2. electric- popular, quieter, cuts with high torque, less stalling, smoother cutting
In regards to the coupler, what does the high speed have that the slow speed does not have?
fiberoptic
Distal diameter of a 330 bur
0.8mm
Length of 330 bur
1.5mm
Taper of a 245 bur
4 degree
Taper of a 330 bur
8 degree
Length of a 245 bur
3mm
Neck of a bur is thinner for
operators visibility
2 mechanisms of cutting
- brittle fracture
2. ductile fracture
Abrasive cutting is MORE efficient with … materials
brittle (like enamel) (micro cracks)
Abrasive cutting is NOT efficient with…. material
ductile (dentin)
Ductile fracture mechanism of cutting is…. deformation of the material by shearing
plastic
Bladed cutting more efficient is MORE efficient with … material
ductile
Blade design- The surface that forms the chip and the surface of the blade towards the direction of cutting
Rake face
Blade design: The surface that clears the chip and that goes away from the direction of cutting
Clearance face
The angle that provides clearance between the cutting edge and the tooth structure
clearance angle
Angle between the radial line and the rake face
rake angle
angle between the rake and clearance surfaces
edge angle
… rake angle has a higher cutting efficiency and larger chips are produced. But there is a small chip space so its more likely to clog
Positive
A rake angle is positive when the blade is… to the perpendicular
behind
A rake angle is negative when the blade is … of the perpendicular
in front
….rake angle has a decreased cutting efficiency and smaller chips are produced so there is no clogging
negative
Purpose of the clearance angle
prevents blade from rubbing on the tooth surface
…clearance angle means less friction, dulling minimized and bur life lengthened
Bigger
Vibration and heat generation may lead to …
plural trauma and discomfort to the patient (water coolants used)
1st number of the 3 unit instrument formula is the…
width of blade (10 = 1mm)
2nd number of the 3 unit instrument formula is the
length of blade (7=7mm)
3rd number of the 3 unit instrument formula is the
angulation of the blade to the long axis of the handle (14)
Gingival margin trimmer does what kind of cutting?
lateral
