week 5 Flashcards

1
Q

what is the presence of removable appliances in the US

A

crozat applianes in early 1900s then dropped out of favor

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2
Q

what is the presence of removable appliances in Europe

A

complete reliance on andresen activators, schwarz between 1925-1965

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3
Q

Pros of removable appliaces

A

removable
More hygience
more esthetic
Easter for certain growth mod than fixed

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4
Q

disadvantages of Removable appliances

A

Rely on patient compliance
Less Precise force control than fixed appliances
involves lab work

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5
Q

Primary use of removable appliances

A

GRowth modification

minor tooth movements retention

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6
Q

what does a bionator do

A

Stimulates mandibular growth

Controls tooth eruption

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7
Q

what does a twin block do

A

Stimulates mandibular growth
Can include an expander
Can add headgear

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8
Q

what does a frankle appliance work on

A

Tissue borne with buccal shields/lip pads to reduce cheeck and lip pressure for expansion

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9
Q

what does a frankle appliance do

A

stimulates mandibular growth (lingual pads)

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10
Q

why use a face mask and reverse pull HG

A

for preadolescent patients exhibiting maxillary deficiency

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11
Q

how does a removable appliance work for tooth movement

A

Force for active tooth movement provided by finer springs

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12
Q

what provides retention for removable tooth movement devices

A

Acrylic, Labial bow and molar clasps

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13
Q

why use an anterior bite plate

A

Decrease overbite

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14
Q

why use a posterio bite plate

A

to increase overbite

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15
Q

what is a Hawley retainer

A

A labial bow, with clasps or rests on posterior teeth in acrylics with many variations of designs

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16
Q

why use spring retainers

A

Both retention and minor tooth movement

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17
Q

why use a tooth positioner

A

Minor tooth movement and retention

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18
Q

how is a tooth positioner set up

A

Fabricated on set-up models to which desired (minor) tooth movement has been included

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19
Q

what are contemporary ortho fixed appliances based on

A

Angle’s design in the 1800s

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20
Q

what are angle’s 4 major designs for fixed ortho appliances

A

E arch
Pin and tube
Ribbon
Edgewise

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21
Q

what did angle’s edgewise appliance do to modernize ortho

A

each bracket had horiztonal slots for better control of torque

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22
Q

how did the begg appliance control tooth movement

A

Modification based on Angle’s ribbon arch

except used auxilary springs for root control

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23
Q

how did the Begg appliance compare to the Edgewize

A

Begg had a wire and bracket contact that was small with minimal friction so teth can be moved quickly
- hard to control root

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24
Q

do we still use the begg appliance

A

No

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25
Q

what is the design of automatic rotational control

A

Twin brackets or single brackets with wings

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26
Q

what slots are used today in brackets

A

.018 and .022 inch slots

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27
Q

when was the pre-adjusted edgewise appliance developed

A

in the 1980s

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28
Q

how did the pre-adjusted edgewise appliance help

A

Refined manufacturing with built in adjustments for each tooth
- no repeated bends to compensate for difference amount teeth (required for standard edgewise appliance)

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29
Q

what is the straight wire technique

A

elements of ideal tooth prescriptions are fabricated into the appliance to minimize wire manipulation

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30
Q

is wire bending needed anymore

A

it is needed for the detailing and finishing phase as the ideal prescription may not be exactly ideal for individual patients and teeth

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31
Q

how does one compensate for differences in tooth horizontal position

A

by varying bracket base thickness or molar tube profile differences of tooth position using (first order, or in-out archwire bends)

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32
Q

when are 1st order bends used

A

in a standard edgewise band to compensate for horizontal position variations

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33
Q

how to adjust a pre-adjsted edgewise appliance for the horizontal

A

Make the bracket base of upper lateral incisors,
lower incisors thicker
Molar tube profile shorter than adjacent bracket slots

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34
Q

how to aid in changes mesio-distal angulation in standard edgewise

A

vary bracket slot tipping using 2nd order bends

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35
Q

how to do mesial distal angulation in preadjusted brack

A

align vertical slot with root of long axis, if alignment needed straight wire will be defllected once engaged to that tooth causing a change in angulation

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36
Q

how do you compensate for labial lingual angulation

A

3rd order bends

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37
Q

what are the steps of doing banding

A

Tooth separation
Band fitting
Band cememntation
- sealing with wax before curing adesive

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38
Q

what are the aspects of brackets

A

Direct and indirection bonding

Rebonding and debonding

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39
Q

what should archwire be adjusted to

A

Make sure the jaw/size/ype of archwires are correct

- know properties of different types of arch wire

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40
Q

hos is archwire tied to brackets

A

Elastic and stainless steel ties

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41
Q

why use power chains

A

Space closure

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42
Q

why use elastics

A

Improve occlusion move impacted teeth

shift midlines

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43
Q

why use open coil springs

A

Opening space

retracting teeth

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44
Q

why use closed coil spring

A

maintaining space

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45
Q

what are the fixed appliances for correcting class II occlusion

A

Herbst
MARA
Forsus

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46
Q

what are the advantages for class II correction

A

Patient compliance not need
larger dental movement than elastics
Herbst and MARA may be potentially have skeletal growth modification effects

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47
Q

what to use a jasper jumper to fix

A

Class II correction

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48
Q

when to use a lip bumper

A

Arch expansion
Molar distalization
Incisor proclination

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49
Q

what is a hyrax used for

A

Palatal expansion of the skeleton and dental

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50
Q

what does a lower arch expander expand

A

dental only

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51
Q

when to use a quad helix with finer sprins and w arch

A

preadolescent and early mixed dentition patients

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52
Q

what are helicies of a quad helix with finer springs used for

A

Activation and increase in range of tooth movement

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53
Q

what stainless steel is used with quad helix with finger springs and W arch

A

heavy (.040)

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54
Q

why use a transpalatal arch and lingual holding arch

A

Used for anchorage and space maintenance purposes

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55
Q

what arch wire is used for transpaltal arch and lingual holding arch

A

Heavier (.036 or above, stainless steel) than regular archwires

56
Q

why use a pendulum appliance

A

Molar distalizaion

57
Q

what is a pendulum appliance bound to

A

Bound to premolars

58
Q

how does a pendulum appliance work

A

TMA wires with helicies inserted to molar tubes
Anchorage from palate
Primarily molar movement with some movement of anterior teeth as well

59
Q

why use a habit appliance

A

To correct tongue or finger habit

60
Q

what wire is used in a habit appliance

A

Heavy stainless steel wire

61
Q

what is a habit appliance anchored to

A

Molars

62
Q

what is the measure of force we use as a dentist

A

grams

63
Q

what happens when you resolve a force vector

A

will produce compnents

64
Q

is vector resolution the same as vector addition

A

opposite

65
Q

how can you add vectors

A

resolve them to components in the 3 planes

66
Q

what is the center of resistance

A

a point at which resistance to movement can be concetrated for mathmetical analysis

67
Q

what determines the center of restistance for a free and retrained object

A

Free: center of mass/point of balance

Partially restrain: nature of external constains

68
Q

where is the center of resistance for a teeth

A

the approximate midpoint of what is embedded in bone (Halfway between the apex and alveolar crest)

69
Q

what does the center of resistance vary with

A

Alveolar bone height and the amount of root in both

70
Q

does the center of restisance depend on ortho force

A

No (unless force changes bone height)

71
Q

where does the center of resistance move during alveolar bone loss

A

Moves apically

72
Q

where does the center of resistance move during root resorption

A

Moves coronally

73
Q

what happens if the line of action does not pas through Center of resistance

A

Produces rotation of the tooth

- a moment

74
Q

what is magnitiude

A

Mangitude of force times the perpendiculat distance from the Center of restistance to the line of action

75
Q

what is a couple

A

2 forces, equal in magnitude, parallel and non colinear in oppsite direction

76
Q

what does a couple produc

A

Pure rotation

77
Q

what does a single force produce

A

rotation plus translation

78
Q

how does a couple produce a pure rotation

A

The translational forces cancel out

79
Q

what is the center of rotation

A

the point around which an object rotates

80
Q

can the center of rotation change

A

yes, varies with force/moment/couple applied tot he tooth

81
Q

why would you change the center of rotation

A

Different types of tooth movement and clinical goals

82
Q

types of ortho tooth movement

A

Translation
Pure rotation
Combo of translation and rotation (tipping)

83
Q

what is translation

A

All points on an object move in the same direction in the same rate

84
Q

where must the line of action pass to do translation

A

Need to pass through center of resistance

85
Q

does the bracet position determines translation

A

No, line of action determines

86
Q

how can you produce translation without a force passing through the center of resistanec

A

canceling the moment produced by using a opposite moment created by a couple

87
Q

what is tipping

A

when some points on an object move differently (direction, rate, both) than other points on the same object

88
Q

where does the line of action pass to induce tipping

A

Does not pass through center of resistnace

89
Q

what can a tipping movement be resolved to

A

Translational and rotational components

90
Q

how does one determine the center of rotation

A

Examining to movements of two points on the tooth

91
Q

where is the center of rotation for translation

A

Infintiy

92
Q

where is the center of rotation for uncontrolled tipping

A

slightly apical to Center of resistance

93
Q

where is the center of rotation for controlled tipping

A

Apex

94
Q

where is the center of rotation for root movement (torque

A

Incisal edge

95
Q

where is the center of rotation for pure rotation

A

C res

96
Q

what is the difference in controlled and uncontrol/simple tipping

A

uncontrol: tooth rotates around a center near the middle of the root
control: tooth rotates around its apex

97
Q

what is hooks law

A

Force of spring equals negative spring constant times the distance the spring is pulled on

98
Q

what are most ortho archwires made of

A

Elastic (but both elastic and plastic phases are important)

99
Q

what causes the Force deflection curve to change

A

Archwire diameters and material

100
Q

what is stress

A

the force/area

101
Q

what is strain

A

Change in length/original length

102
Q

what is the elastic modulus

A

stress/strain

103
Q

what is the slope of the stress strain curve

A

Elastic modulus

104
Q

how is elastic modulus related to stiffness

A

directly

105
Q

how is elastic modulus related to springiness

A

inversely

106
Q

what is the difference of stress strain and Force deflection curve

A

S/S: intrisic (what maters is materials)

F/D: extrinsic (what maters is materials and shape/length)

107
Q

should a homogenous material of differnet dimension only have one S/S or one F/D

A

one S/S but different F/D with different dimensions

108
Q

what is springiness in a graph

A

1/stiffness

109
Q

what is stiffness in a graph

A

slop of the linear portion of The F/D curve of the elastic modulus of the S/S curve

110
Q

what is springback

A

The ability to return to OG shape

111
Q

how long is spring back useful for

A

Beyond the lastic limit

112
Q

what is range

A

The distance a wire can be bent elastic before permanent deformation

113
Q

where does permanent deformation occur

A

at the yield point, .1% greater than the proportional limit

114
Q

what is strength

A

Stiffness x range

115
Q

what is the resiliance in a graph

A

Area under the S/S curve out to the proportional limit

116
Q

what is formability

A

Amount of permanent deformation a wire can withstand before failure

117
Q

what is the ideal ortho archwire characteristisc

A
High strength
Low stiffness
High range
high formiability
Capacity to taking weld/solder
118
Q

what is the benifit of high strength

A

Produce desired force magnitude without excessive deflecting the AW

119
Q

what is the benifit of low stiffness

A

Produce relatively constant force

120
Q

what is the benifit of high range

A

Can deflect the AW to a great etend without permanent deformation

121
Q

what is the benifit of High formability

A

Make bends on the AW without breaking it

122
Q

is the ability to take weld/solder a mech property

A

No

123
Q

what does the shape of an archwire affect

A

Shape control shear/tension force but not bending force

124
Q

what does the cross-section diamter of AW affet

A

For bending

125
Q

what does tying an archwire to brackets do to strength, springiness, and range

A

Increases strenth

decrease Springiness and Range

126
Q

why add loops to an archwire

A

Increase range and springiness

127
Q

what is the strength ranking of wires

A

Stainless> TMA>NiTi

128
Q

what is the stiffness ranking of wires

A

Stainless> TMA> NiTi

129
Q

what is the range of different wires

A

NiTI>TMA>stainless

130
Q

what is the ranking of force required to cause the same level of deflection

A

Most force: stainless
Nitol
NiTI

131
Q

what causes the superelastic property of Superelastic NiTI

A

phase transition between Austenitic and Martensic phases

132
Q

what arch wireis used for inital alignment

A

Small size NiTI or steinless stels (if formability is needed

133
Q

what arch wire is used for leveling

A

Relatively large size TMA or steel archwire

134
Q

what AW is used for torque

A

Large rectangular Steel or TMA

135
Q

what AW is used for finishing

A

Steel or TMA with size depending on purpose

136
Q

what AW is used for growth modification device

A

LARGE stainless steel wires not used as common archiwre