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97 Cards in this Set
- Front
- Back
What the name for a cast alloy that is rolled thin, worked, pulled into a wire or bent and becomes stronger and harder?
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wrought alloy
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What are two common examples of wrought wire?
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ortho wire
RPD clasp wire |
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True or false, wrought wire properties are virtually identical to cast alloy
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false
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The grains inwrought wire are (bunched/elongated), contain (very little/a lot) of distortion
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elongated, a lot
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"cold-working" takes place at what temperature?
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room temp (so it's somewhat of a misnomer)
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line defects and dislocations are known as (point/lattice) imperfections
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lattice
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Dislocations are (2/3) dimensional defects
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3
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What 3D defect is responsible for the peculiar mechanical properties exhibited by metals?
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dislocation
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What is the term for the linear array of atoms each of which has a coordination differing from the normal coordination of those atoms in the structure?
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dislocation
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The charge field around each metal atom is (different/the same), this allowing dislocation
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the same
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Impurities, atoms of (smaller/larger) size and grain boundaries act as obstructions and cause the dislocations to pile-up, resulting in (amplified/impaired) dislocation movement, which eventually distorts the grain and results in the (softening/hardening) of the metal if it is stressed more. This process is called ____
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larger, impaired, hardened, strain-hardening (or work-hardening, cold-working)
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What are two other terms for strain-hardening?
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work-hardening
cold-working |
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(Large/small) grains are stronger because they have (more/less) dislocation barriers
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small, more
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Small grains can be defined as (fine/coarse)
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fine
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Twinning occurs at (high/low) strain rates and (high/low) temp
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high, low
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Atoms have mirror orientation relationship with each other in metals with relatively few slip systems is referred to as ___
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twinning
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What is the reversal of the effects associated with cold-working by heating the metal to an appropriate elevated temp?
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annealing
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Annealing is the reversal of the effects associated with what?
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cold working
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What is the stage at which cold-work properties disappear, no significant microscopic change, and has residual stress?
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recovery
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What is the term for the change in microstructure, new strain-free grains in areas of severe cold-work (grain boundaries) or severe deformation; ductile
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recrystallization
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What is the stage where there is growth of fine grains to larger coarse grains?
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grain growth
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What are the 3 stages of annealing?
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recovery, recrystallization, grain growth
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Say whether TENSILE STRENGTH and DUCTILITY increase or decrease during these 4 stages:
cold-working recovery recrystallization grain growth |
cold-working (D decrease, TS increase)
recovery (D same, TS decrease) recrystallization (D increase, TS decrease) grain growth (D increase, TS decrease) |
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At which phase of annealing are Tensile strength and ductility BOTH increasing? Both decreasing?
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None! Always going in opposite directions (except recovery where ductility does not change)
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Compared to cast alloy, wrought metals:
(higher/lower) elastic modulus (higher/lower) plastic deformation (aka ductility in cast alloy) (higher/lower) flexibility (higher/lower) yield strength and hardness (elongated/compressed) grains |
UNCHANGED (elastic modulus is = in WW and CA), lower, higher, higher, elongated
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Optimal ortho wire produces (heavy/light) and (variable/continuous) force
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light, continuous
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It is critical that ortho wires (do/do not) decrease rapidly and decay away
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do NOT
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List these in the proper order of creating archwire:
heat treatment to eliminate work-hardening of wires mechanical reduction of cross-section for drawing of round wire casting of ingot mechanical reduction of round wire by rollers to produce rectangular wires (w/slight rounding of edges) |
ingot, mechanical reduction of cross-section, mechanical reduction of round wire, heat treatment
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There was a whole "duh" slide about how there is archwire variety and that orthodontists need to know the properties, etc...
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move along
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Elastic range is also called ___ range
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working
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What is the distance a wire will bend elastically before permanent deformation occurs?
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elastic range
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Permanent deformation occurs at a metals ___ limit
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proportional
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The distance the wire will deform plastically before it fractures is called the ___ range
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plastic
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Between proportional limit and fracture is known as the ___ range
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plastic
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You bend an archwire to which one?
The form you want the teeth to have The form the teeth currently have |
The form you want the teeth to have
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If lots of force is used in friction of the wire, it will results in (more/less) force to actually move the teeth
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less
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Amount of deformation recovery, upon unloading, beyond the proportional limit is called
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springback
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YS/E or PL/E is called
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springback
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more springback, (more/less) deformation wire can undergo and then recover from
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more
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pseudoelasticity is also called ___
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superelasticity
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What types of wires can undergo superelasticity?
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Ni-Ti
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Ni-Ti undergo ___-induced transformation to high-stress martensitic Ni-Ti phase by work-hardening mechanism
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stress
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You heat a Ni-Ti wire and heat it to 480C and give wire ideal arch form... then allow it to cool to room temperature and then place the wire in the patients mouth (25-27C) returns wire to what it was when it was originally heated. This phenomenon is called:
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shape memory
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In shape memory, the wire is heated to a high temperature, cooled and heated back to the same initial high temperature
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False! High temp, low temp, slightly higher temp
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4 main compositions of ortho wire are
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stainless steel
Co-Cr Ni-Ti Beta-Ti |
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What is the ONLY kind of stainless steel wire used in ortho?
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austenitic
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What are the three kinds of stainless steel wire?
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ferritic, martensitic, austenitic
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What are the 4 subclasses of Co-Cr wire?
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soft
ductile semi-resilient resilient |
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What are the 3 subclasses of Ni-Ti wire?
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conventional (non-superelastic)
pseudoelastic thermoelastic |
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How many subclasses of Beta-Ti wire are there?
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None! Bye!
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Austenitic is AISI __ and ___, or ___ (all numbers)
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302, 304, 316L
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Which type of stainless steel wire is not used in ortho but is used as surgical instrumentation?
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martensitic
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Austenitic wire 302 and 304 is for ___ wire while 316L is for ___
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ortho; low C (carbon) concentration, implants, brackets, etc.
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Which type of stainless steel is MOST corrosion resistant?
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austenitic
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Ferritis and Martensitic stainless steel are AISI # ____
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400
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Martensitic stainless steel has:
(high/low) strength and hardness (high/low) ductility (high/low) corrosion resistance (is/is not) heat treatable |
high, low, low, is
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In an 18-8 wire, what do these #s mean?
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18 = 18 wt% Cr
8 = 8 wt% Ni |
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What are the approximate concentrations of Fe, Cr, Ni, and C in austenitic 18-8 stainless steel wire?
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70%, 18%, 8%, 0.15% or 0.08%
(spec 302 = 0.15% whereas spec 304 = 0.08%) |
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Austenitic 18-8 SS wire has:
(high/low) elastic modulus (high/low) stiffness (high/low) ductility (good/poor) in ability to overcome sensitization |
high, high, high, good
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Austenitic 18-8 SS wire has:
(good/poor) joinability with soldering (good/poor) formability (good/poor) corrosion resistance |
All 3 are GOOD
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Austenitic 18-8 SS wire has:
(higher/lower) springback than newer wire (high/low) bracket friction |
lower, low
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True or False, Austenitic 18-8 SS wire releases Ni
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True
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True or False, Austenitic 18-8 SS wire is available in only 1 cross section geometry due to it's difficult handling properties
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False, available in many different cross sections
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Austenitic 18-8 SS wire is heat treated between __ and __ C to minimize breakage be eliminating residual stress
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400-500
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What is the process of precipitation of Cr3C in grain boundaries at temps above ___C leading to loss of passivation, decreased resistance to corrosion, and partial disintegration
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sensitization, 400
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Addition of an element that will precipitate as a carbide in the preference to Cr is called
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stabilization
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Twisting or braiding a wire leads to (lower/higher) EM, this making the wire (more/less) stiff
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lower, less
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Co-Cr wires have properties that are:
a. similar to SS wire b. much worse than SS wire c. much better than SS wire d. identical to SS wire |
a. similar to SS wire
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What are the % compositions of the following elements in Co-Cr wire?
Co, Cr, Fe, Ni, Mo, Mn, C, Be |
Co 40, Cr 20, Fe 15.8, Ni 15, Mo 7, Mn 2, C 0.15, Be 0.04
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Rank these colors of Co-Cr wire from hardest to softest:
red, blue, yellow, green |
Red
Green Yellow Blue (Mnemonic: Run and Get Your Burs) |
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Co-Cr wires have:
(good/bad) formability (higher/lower) springback than newer wires (higher/lower) EM than SS wire |
good, lower, same (wasn't an option... now you won't forget!)
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Co-Cr can be heat treated at ___C to increase stiffness and torsional strength
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500
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Co-Cr wires have:
(good/poor) corrosion resistance (high/low) bracket to wire friction levels (is/is not) joinable with soldering |
good, low, is
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Ni-Ti wires have what % of Ni, Ti and Co?
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Ni 52, Ti 45, Co 3
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Ni-Ti wires have:
(good/poor) springback and flexibility (true/pseudo) shape memory (low/high) EM compared to SS wire |
good, true, low (in fact, only 20% of that of SS wire!)
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Ni-Ti wires have:
(higher/lower) frictional forces compared to steel alternatives (good/poor) formability and joinability heat treatment at __-__C |
higher, poor, 500-600
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Which type of wire allows for "variable-modulus" orthodontics?
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Ni-Ti
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What type of wire is best in a highly curved root canal?
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Ni-Ti, bc of its low EM
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Beta-Ti wires have what % composition of Ti, Mo, Zr, Sn
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Ti 77, Mo 11, Zr 6, Sn 4
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Some new versions of Beta-Ti wires have a __+ ion added
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N
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Beta-Ti wires have:
(higher/lower) EM than SS wire (high/low) ductility (high/low) springback) (good/poor) formability |
lower, high, high, good
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What is the ONLY wire possessing true weldability?
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Beta-Ti
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True or False, you should not heat-treat Beta-Ti wires
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true
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True or False, Beta-Ti wires contain the most Ni of the 4 wires
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False, NO Ni at all!
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Beta-Ti wires have:
(high/low) bracket to wire friction due to a (smooth/rough) surface |
high, rough
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Rank the 4 wires in order from highest to lowest in terms of EM (elastic modulus)
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Co-Cr
SS Beta-Ti Ni-Ti |
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Rank the 4 wires in order from highest to lowest in terms of yield strength
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SS
Co-Cr Beta-Ti Ni-Ti |
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Rank the 4 wires in order from highest to lowest in terms of stiffness
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Co-Cr
SS Beta-Ti Ni-Ti |
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Rank the 4 wires in order from highest to lowest in terms of ductility
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SS and Beta-Ti are tied
Ni-Ti = "poor" Co-Cr = "low" |
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Rank the 4 wires in order from difficult to easy in terms of ease of soldering
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Ni-Ti
Beta-Ti Co-Cr = reasonable/moderate SS = reasonable |
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Ticonium is an alloy of what 4 metals?
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Co-Cr-W-Ni
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Co-Cr-W-Ni make up the alloy known as ___
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ticonium
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Retention pins are usually made of what type of wire as well as Ti and Ti alloys?
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18-8 SS
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How is the cutting edge of an endo file created?
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by twisting a wire blank
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Rotary Ni-Ti are (nonsuperelastic/superelastic)
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superelastic
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The old technique was to use (superelastic/nonsuperelastic) Ni-Ti endo files by hand
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nonsuperelastic
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The superelastic plateau region of the graph is from point __ to __ (letters) a
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b to c
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