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Ortho > fixed appliances > Flashcards

fixed appliances Flashcards

1
Q

definition

A

an appliance which is fixed to the teeth and can’t be removed by the patient
consists of brackets, bands, archwires and auxillaries
precision tooth movements

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2
Q

advantages of fixed appliances

A

3D control
complex tooth movements
control of root movement
less dependent on compliance

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3
Q

disadvantages of fixed appliances

A

requires excellent OH
risk of iatrogenic damage - white marks
poor intrinsic anchorage - don’t have palate for anchorage

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4
Q

advantages of removable appliances

A

less risk of iatrogenic damage - can clean more effectively

good intrinsic anchorage

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5
Q

disadvantages of removable appliances

A

only simple tooth movements- tipping
no control over root movement
greater compliance required
can be lost

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6
Q

indications for fixed appliances

A 
camouflage (correction of mild to mod skeletal discrepancies)
alignment of teeth
correction of rotations
centreline correction
OJ and OB reduction
closure of spaces/creating spaces
vertical movements of teeth
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7
Q

treatment goal - Andrew’s 6 keys

A

tight approximal contacts, no rotations
class 1 incisors
class 1 molars
flat occlusal plane or slight curve of spee
long axis of teeth have a slight mesial inclination except from the L incisors
the crowns of the canines back to the molars have a lingual inclination

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8
Q

history of fixed appliances

A

1 - bands made individually for each tooth
2 - direct bonding (brackets) - Edgewise.
- have to put bends in wire - time-consuming and challenging
- spaces closed using springs
3 - pre-adjusted Edgewise “straight wire”
- no longer need to pre-bend wire
- arch wire slot individualised for each tooth

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9
Q

components

A 
bracket/tube
band
archwire
modules
auxiliaries
anchorage components
force generating components
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10
Q

components of bracket

A

bracket slot
tie wings
bracket base

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11
Q

bracket materials

A

metal: SS, (CoCr, Au)
polymers: higher friction, not as strong
ceramics: hard to remove post treatment

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12
Q

types of self-ligating bracket

A

passive

active

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13
Q

passive self-ligating brackets

A

reduced friction, wire not held in gap, freely moving to slide

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14
Q

active self-ligating brackets

A

little spring which holds wire in slot
no modules to put on bracket
increased friction so not as good for sliding

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15
Q

how are brackets attached?

A

connected to bands or directly bonded on the teeth

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16
Q

function of brackets

A

hold arch wire in place

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17
Q

bands

A

SS ring which encompasses tooth with pre-welded attachments

- tubes and sometimes lingual/palatal cleats (run elastics)

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18
Q

how do you attach the ortho attachment to the band?

A

weld/solder

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19
Q

where are bands mostly used and why?

A

on molars as need increased bond strength

can also use if a tooth is heavily restored

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20
Q

what are bands cemented on with and what need to be done before placement?

A

GIC

space required - separator visit 5-7 days before

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21
Q

why might pt complain of jag cheeks with a band and how do you treat this?

A

as teeth align surplus wire may protrude distally out of tubes

cut surplus flush with tube

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22
Q

auxillaries

A

supplement main components of bands, brackets and archwires
arch wire hooks and stops, cleats, buttons, coil springs, elastomeric, elastics, separators, wire ligatures, TPA, quad helix, headgear

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23
Q

elastomeric modules

A

secure archwire into arch wire slot

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24
Q

force generating components

A

sliding mechanisms
- elastic power chain (close spaces and pull ectopic canines)
- NiTi coils
- IO elastics
- active ligature
teeth move by utilising the energy stored in the elastic or spring
- pull/push teeth away/towards each other along the arch wire

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25
Q

class 2 inter maxillary elastics

A

run from U anteriors to L posteriors

e.g. to reduce OJ

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26
Q

class 3 intermaxillary elastics

A

run from U molar to L canine

to pull lower labial segment back

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27
Q

what does the bracket prescription determine?

A

in/out
tip
torque
control

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28
Q

what is the MBT prescription modified for?

A

to make it suitable to treat the most common malocclusion - class 2

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29
Q

where on the tooth is the MBT prescription for?

A

at the midpoint of the facial surface

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30
Q

in-out control

A

relative bucco-lingual position of teeth

e.g. 2 set palatally, 3 set labially

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31
Q

what determines in-out control?

A

depth of bracket base

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32
Q

tip

A

the mesio-distal angle of the tooth - the angle the tooth makes to the horizontal along the line of the arch
all teeth tip mesially

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33
Q

what determines tip?

A

angle of the horizontal slot

34
Q

what tooth movements can a round AW achieve?

A

tipping and vertical tooth movements

35
Q

torque

A

bucco-lingual angle (inclination) of the tooth

  • U incisors inclined labially
  • UBS inclined palatally
  • all lowers inclined lingually
36
Q

what determines torque?

A

angle between the bracket base and slot

37
Q

when does torque only happen and why?

A

when you use a rectangular wire
engages wall of slot
the closer the fit between the arch wire and bracket slot the greater the degree of control
get force couple with interaction between arch wire and walls of bracket - apical and rotational movements

38
Q

composite bonding techniques for brackets and tubes

A

acid etch technique

self-etching primer (transbond plus)

39
Q

what does the bracket have to enhance bonding?

A

mesh base to increase SA

40
Q

why shouldn’t you really use GI to cement brackets?

A

decreased bond strength

41
Q

what is GI used to cement?

A

molar bands

42
Q

how does the arch wire shape change throughout tx?

A

start round them progress to rectangular

43
Q

arch wire materials

A 
NiTi
SS
CoCr
B-Ti (TMA)
composite
glass
44
Q

SS wires

A

often use early
working AWs to slide teeth (low friction)
hypodontia/to open gaps - slide teeth to create space (then align with NiTi wire)
formable - AW bands, loops
multistrand - flexible

45
Q

NiTi wires

A

flexible
light continuous force - low force delivery over large deflection
shape memory - return to original shape, difficult to distort
higher friction than SS - because surface isn’t as highly polished

46
Q

anchorage

A

resistance to unwanted tooth movement

47
Q

Newton’s 3rd law

A

every force has an equal but opposite reactionary force

48
Q

what is the first aspect of treatment planning?

A

anchorage

49
Q

why are fixed appliances anchorage demanding?

A

you are just involving teeth

50
Q

TADs - absolute anchorage

A 
non-osseointegrating mini screw
won't move under force
major development in ortho
 - anchorage control
 - tooth movement mechanics
51
Q

TADs failure rate

A

low e.g. comes loose

v few problems

52
Q

how to use TADs

A

LA then insert between roots

53
Q

uses of TADs

A 
retract canine distally (inter-radicular TAD)
intrude molars (palatal TAD between 5 and 6s)
- close AOB (prev would have required surgery)
54
Q

cortical anchorage

A

cortical plates provide increased resistance to tooth movement
- buccal roots start to hit cortical plates as move forward because maxilla gets narrower

prevents mesial molar movement
TPA and lingual arch
maintains intermolar width
also transverse anchorage

55
Q

Nance palatal button/arch

A

utilises palatal vault for anchorage reinforcement
stops molars from tipping and prevents mesial drift
can potentially further increase anchorage

56
Q

headgear

A 
traditional headgear use is in decline
sometimes still use protraction gear for class 3 - maxilla more amenable - can disrupt sutures and move forward
57
Q

headgear safety

A

must ensure appropriate safety mechanisms to prevent catapult ocular injuries from face bows
- locking devices
- safety release springs
written and verbal instructions

58
Q

retention

A

maintaining the final tooth position with a passive orthodontic appliance

59
Q

what is the aim of retention?

A

prevent relapse

60
Q

types of retainers

A

fixed

removable

61
Q

consent stage - retention

A

lifelong retention required

pt decision - wear for as long as you can unless you want to take the risk of relapse

62
Q

features with high relapse potential

A 
diastema/space closure
rotations
palatally ectopic canines
proclination of L incisors
AOB
instanding U lateral incisors
63
Q

what type of retention should be given to high relapse risk patients?

A

bonded retainers

64
Q

PFRs

A

clear overlay retainers
variety of materials and thicknesses
can include prosthetic tooth for aesthetics
well-tolerated

65
Q

PFRs wear pattern

A

varies between clinicians
2 weeks full time wear except eating and drinking, night only thereafter
or straight to nights only

66
Q

types of removable retainer

A

PFRs

Hawley removable retainer

67
Q

Hawley retainer

A

1920s
labial bow to control incisors and canines
not well tolerated in the L arch
can add prosthetic teeth

68
Q

clinical situations for a fixed retainer

A 
spaced arch
diastema
proclination of lower labial segment
PD cases (can also use as splinting for mobile teeth)
ectopic canines
instanding U2s
69
Q

bonded wire retainer maintenance

A

requires careful monitoring and ID cleaning
ensure composite attachments intact and sound
refer back to orthodontist if problems

70
Q

Orthoflextech

A

good for L anteriors

cant use for upper incisors as space between composite bonds too big so can get movement

71
Q

rigid canine bars

A

canine to canine
0.032 inch SS
some companies provide preformed
maintain IC width so incisors can’t move

72
Q

winged retainer

A

issue if one wing fails

73
Q

types of fixed retainer

A

bonded wire retainer
Orthoflextech
rigid canine bars
winged

74
Q

risks of fixed appliances

A

decalcification - monitor throughout tx
root resorption
relapse
gingival recession - esp if pre-existing in adult patient

75
Q

pt journey

A

assessment and diagnosis - tx aims
tx plan and informed consent
commence tx

76
Q

average case length

A

18-24m

77
Q

hypodontia, ectopic canines, orthognathic case length

A

24-30m but v variable

78
Q

frequency of routine adjustments

A

every 4-8 weeks

79
Q

initial problems encountered

A

pain
mucosal irritation
ulceration
appliance breakage

80
Q

GDP role

A

continue to see pt for routine care and check ups - reinforce OHI and diet advice
liase with orthodontist if concerns
make appliance safe in case of an ortho emergency
- snipping of jaggy wire
- removal of loose component

Ortho (21 decks)

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