Properties of Ortho Arch Wires

  1. define the load/elongation curve
    L/E curve takes into consideration the geometry of the specimen aka extrinsic stiffness
  2. define S/S curve
    normalizes out geometry aka intrinsic stiffness
  3. true/false: elastic modulus can be obtained from a L/E curve
    false. it cannot be obtained from the L/E curve
  4. define stress
  5. define proportion limit
    point at which any permanent deformation is first observed
  6. define yield point
    deformation of 0.1%, wire will not return to its original state
  7. define ultimate tensile strength
    maximum load, greater than yield strength
  8. define failure point
    point at which the wire breaks
  9. define stiffness
    proportional to elastic modulus. steeper slope = stiffer wire.
  10. define springness
    1/stiffness or 1/elastic modulus. more horizontal the slope = springier wire.
  11. define range
    distance wire will bend elastically before permanent deformation
  12. define strength
    stiffness x range
  13. define resiliance
    area under S/S curve from 0 to proportional limit/yield stength
  14. define formability
    amount of permanent bending the wire will tolerate before it breaks or fails. area under S/S curve from YP to FP
  15. what happens to strength, stiffness, springiness and range if the diameter is increased?
    • increase: strength, stiffness
    • decrease: springiness, range
  16. what happens to strength, stiffness, springiness and range if the length is increased?
    • increase: springiness, range
    • decrease: strength, stiffness
  17. round or rectangular wires elicit more force?
    rectangular (more stiffness)
  18. list 4 ways loops are used in arch wires
    • 1. align teeth
    • 2. increase force of the wires
    • 3. increase flexibility of wires
    • 4. hold soft tissues away from orthodontic brackets
Card Set
Properties of Ortho Arch Wires
arch wires