Week 1 Flashcards
What are 2 types of hand pieces?
What’s the difference?
- Air driven:
- been around for many years - Electric:
- getting popular
- quieter
- cuts with higher torque
- higher power
- less stalling
- smoother cutting (more milling than chopping)
RPM’s of slow, medium and high speed handpieces?
Slow: 200,000rpm
which handpiece (low speed/high speed) will have less patient discomfort? why?
high speed bcz:
- it is more efficient
- less vibration
- less pressure
what are the hole connectors in high speed?
drive air, exhaust, fiber opitc, water (coolant), air (coolant)
what’s the function of coupler?
- attaches hand piece to the delivery unit
- supplies air and water to handpiece
What are the uses of slow speed?
- finishing and polishing (whether it is restoration or a prep) (intra oral or extraoral)
- cleaning external surface of teeth (coronal polishing)
what type of bur go into the straight handpiece?
what’s the straight handpiece used for?
long shank type bur / straight bur
use in extra oral procedures: finishing a crown
what type of heads accept “latch type” burs?
low speed with either one of the following heads:
- swing latch
- push button latch
- spring latch
what type of heads “friction grip” head? what’s the mechanism for each one?
low speed with either one of the following heads:
- push button type: friction generated from an internal spring assembly
- bur tool type: a special tool using force to overcome and generate friction
what type of burs fit into the “latch type head”?
only latch end burs
difference btwn friction grip type bur and latch type bur?
friction grip type bur are:
-smaller diameter and
-shorter shanks
than latch type
components of rotary instruments
in order: head, neck, shank
why is the neck of the rotary instrument small?
so it wouldn’t interfere with operator’s visibility
classify bladed instruments based on the number of blades
- excavating / cutting burs (6 or 8 blades)
- finishing burs (10-20 blades)
2a. red: 10-12
2b. yellow: 16-20
2c. white: 30 blades
what are the characteristics of the carbide burs?
stronger and harder than stainless steel
more brittle than steel
composition of carbide burs?
tungsten carbide head is attached to the steel neck and shank by welding and brazing
composition of the head of diamond burs?
METAL blank on which small DIAMOND particles are held together within a SOFTER MATRIX
which type of bur is used for abrasive cutting?
diamond burs
what are the colors of the shanks for the diamond instruments?
yellow: superfine
red: fine (60-74 micrometers)
blue: medium (88-125 micrometers)
green: coarse (125-150 micrometers)
black: supercoarse
which way is ascending degree of grit? yellow to black? or black to yellow?
ascending degree of grit:
yellow to black
what are the uses of carbide instrument? for diamond instrument?
uses of carbide instrument: intracoronal preparation
uses of diamond instrument: extracoronal preparation
how are coated abrasives made?
abrasives (garnet, quartz, cuttlebone etc) placed on paper flexible backing to form discs or finishing strips
what is used to attach abrasive discsto handpieces?
MANDRELS
what are coated abrasives used for?
finishing restorations (not polishing)
what are the different abbrasives used in molding and coated abrasives?
coated abrasives: garnet, quartz, cuttlebone
molding abrasives: SiC or Al2O3
what’s the composition of molded abrasives?
molding abrasives (SiC or Al2O3) and matrix (rubber, resin) into certain shapes
how are molded abrasives catagorized? give examples
mounted: points and stones
unmounted: discs and stonewheels
or
rigid: griding and shaping
flexible: finishing and polishing
what are finishing strips? coated or molded
coated
shapes of burs? and numbers
round 1/4 - 11 inverted cone 331/2 or 40 pear shape 229 - 333 plain cylindrical fissure 55 to 59 plain tapered fissure 169 to 172 end cutting 900 series cross cut 500 series also 700
state all the numbers that correspond to the mm for round burs
1/4 = 0.5 mm 1/2 = 0.6 mm 1 = 0.8 mm 2 = 1 mm 4 = 1.4 mm 6 = 1.8 mm
dimensions of 330?
length: 1.5 mm
taper: 8 degrees
diameter: 0.8 mm
dimensions of 245?
length: 3.0 mm
taper: 4 degrees
diameter: 0.8 mm
Mechanism of cutting? describe the mechanism of each
brittle fracture: brittle material fractures by crack formation upon tensile loading (like enamel)
ductile fracture: plastic deformation of the material by shearing.
teeth undergo both
which type of cutting is more efficient for brittle material? which one for ductile material?
brittle: abrasive cutting (microcracks)
ductile: bladed cutting (deform then shear)
what does the rake face and clearance face of blade do? which side is towards? which side is away from the direction of cutting?
rake face: -forms the chip -towards the direction of cutting clearance face: -clears the chips -away from the direction of cutting
what’s edge angle?
btwn rake and clearance surface
what’s rake angle?
btwn radial line and the rake face