mechanical properties of arch wires (dr. sun) Flashcards
the F/D curve measures ______ stiffness because is does not include geometry of the specimen
extrinsic
the S/S curve measures ______ stiffness because it normalizes geometry
intrinsic
a homogenous material of different dimensions should only have one ___ curve but will have varies _____ curve
S/S, F/D
stiffness
slope of linear portion of the F/F/ curve or elastic modulous in S/S curve
springiness
1/stiffness
springback
ability to return to original shape. clinically useful springback can be beyond elastic limit
range
distance a wire can be bent elastically before permanent deformation
strength
stiffness x range
resilience
area under S/S curve out to the proportional limit
formability
amount of permanent deformation a wire can withstand before failure
what are the characteristics of ideal ortho archwires
high strength- to produce desired force magnitude without excessive deflecting of the AW
low stiffness- to produce relatively constant force
high range- to deflect the AW to a great extent w/o causing perm deformation
high formability-to make bends on the AW w/o breaking it
capability of taking weld/solder - not a direct mechanical property
wire shape is important for ______ force, not _________ force. for bending force, the ___________ is important regardless of shape
shear (tension) force, bending force, cross sectional diameter
NiTi wires are considered __________ because of phase transition. a wide range of _________force is produced during the austenitic-martensitic phase transition.
superelastic, constant
what type of archwire is required for initial alignment?
small size NiTi or stainless steel (if some formability of the AW is needed)
what type of wire is needed for leveling?
relatively large size TMA or stainless steel
what type of wire for torquing?
large size rectangular stainless steel of TMA
what type of wire for finishing?
stainless steel or TMA, size depends on purpose
growth modification devices require much __________ stainless steel wires than common arch wires.
larger
adding loops _________ (inc/ dec) AW length which _______ (inc/ dec) its range and springiness.
increases, increases
tying and AW tightly to the brackets ______ (inc/ dec) its strength but _____ (inc/dec) its springiness and range
increase, decreases
NiTi wires have _______ stiffness, ________ strength and _________ range, BUT _______ formability
low, good, high, poor
which curve determines force applied to teeth?
force deactivation
the force deactivation curve differs considerable between which two AW types?
stainless steel and NiTi (stainless steel is greater)
