mech principles in controlling ortho force

Question 1

why change ruber bands each day

Answer 1

Lose eleasticity

Question 2

how is a crozat appliance activated

Answer 2

Each time you go to the dentist

Question 3

is gold a good spring

Answer 3

No

Question 4

what do we use as ortho appliances today

Answer 4

Ni-Ti

Beta- ti

Question 5

what is the future of ortho appliances

Answer 5

plastics

Question 6

what are the properties of materials for ortho

Answer 6

strength
stiff/spring
range

Question 7

what is the proportional limit

Answer 7

the point at which the wire begins to deviate from elastic behavior

Question 8

what is yield strength

Answer 8

point at which a measurable deviation is observed

Question 9

what measurment is often shown as the strength of anortho wire

Answer 9

yield strngth

Question 10

what is the goal of an ortho springs mech properties

Answer 10

high strength
best springiness
best range

Question 11

what is resilinece

Answer 11

the area under the curve up to the proportional limit

Question 12

what is formability

Answer 12

area under curve betwen ultimate tensile strenth and failure

Question 13

what is a cantilever beam

Answer 13

attached at one end

Question 14

what is a supported beam

Answer 14

attached at both ends

Question 15

how does doubling a cantilever beam thickness change its physical properties

Answer 15

(2d/d)^3 in stregth
(d/2d)^4 in spring
(d/2d) in rnage

Question 16

how does doubling a supported beam change physical properites

Answer 16

puts the coefficient in front of the eq

Question 17

how does doubling length for a cantilever beam affect it

Answer 17

1/2 strength
springiness 8 times
range in creased 4 times

Question 18

how does one increase springiness and increase change in an ortho wire

Answer 18

lengthening via loop in wire

Question 19

how can you increase strngth and sprininess

Answer 19

long wire with loops to increase betwwn individual teth

Question 20

what does a superelasticity mean

Answer 20

violates hoos law

Question 21

Why is superelasticit possible

Answer 21

materials undergo phase transition witha change in temp or internal stress

Question 22

how can superelasticity exist in the mouth

Answer 22

Due to the material phase change being close in temp to the mouth

Question 23

what material is used in ortho

Answer 23

NiTi with a temp transition like that in mouth

Question 24

how can one reactivate superelastic wire

Answer 24

releasing it then putting it back

Question 25

what the problem with super elastic wire

Answer 25

zero formability

Question 26

what is superelastic wire super useful for

Answer 26

Tipping rotation extrusion crowded/irregular teeth

Question 27

what is a moment

Answer 27

a force delivered at a distance from the objects center of resistance

Question 28

what creates a pure moment

Answer 28

2 equal forces in opposite directions

Question 29

how can you cancel the moment to get bodily movement

Answer 29

Provide force in the oposite direction to the moment in equal magnitude as the moment force

Question 30

what happens as the Mc/Mf ratio becomes more possitive

Answer 30

center of rotation is displaced from center of center of resistance

Question 31

what does it mean when the Mc/Mf=1

Answer 31

tooth moves bodily | center of of rotation is infinately away from center of reistance

Question 32

how do you do anything but tip a tooth

Answer 32

use a fixed attachment | 2 points of contact

Question 33

how does one create Facio-lingo torque

Answer 33

use a rotated wire within a rectangle slot

Question 34

how must wire change when you wnat to slide a tooth

Answer 34

must have a smaller wire to allow for less friction and a wider braket

Question 35

what is the major source of resistance to sliding

Answer 35

corner of the bracket touching, not friide the gowth of jawsction

Question 36

what are the types of removable appliance

Answer 36

Functional for growth mod Activate plates with finger springs and screws for minor toothmovemnt clear aligners for types of malocclusion in adult

Question 37

what is the goal of functional appliances

Answer 37

Guided growth

Question 38

what are the spring properties of screws

Answer 38

Almost zero, so must be screwed every couple days

Question 39

how far does one turn of skrew open plate

Answer 39

.25mm

Question 40

when to use an active plate

Answer 40

produce more physiologic force overa range with tipping force being the main concern

Question 41

should you use invisiline if you need to extract teeth

Answer 41

No

Question 42

what tooth movements does invisiline not work well with

Answer 42

rotation | extrusion

Question 43

what is the basis for all fixed appliances

Answer 43

Angle's edgewise appliance witha bracket in a rectangular slot

Question 44

how is ortho bonding different than restorative

Answer 44

Ortho needs to me removed

Question 45

what is the benifit of bonded breaks

Answer 45

``` vary thickness vary inclination vary torque - reduced wire bending - increased efficiency ```

Question 46

what is the main feature of active-clip braket

Answer 46

springiness of clip adds to the springiness of the wire

Question 47

what is the most common bracket

Answer 47

active-passive clip

Question 48

what is an active passive clip

Answer 48

active when teeth are initially aligned, but create no more force when complete

Question 49

what does a passive-clip bracket need for force

Answer 49

uses only the springiness of the wire to create forces