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Module 8 > Ortho > Flashcards

Ortho Flashcards

1
Q

What way can fixed appliances move teeth?

A

3 planes (3d)

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2
Q

What appliances are more anchorage demanding?

A

Fixed

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3
Q

What 3 movements can fixed appliances make?

A

Tipping
Bodily movement
Torque

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4
Q

What are indications for fixed appliances?

A

Multiple tooth movements needed
Rotations
Bodily movement
Space closure (extractions or hypodontia)
Lower arch treatment

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5
Q

What are contra-indications for fixed appliances?

A

Poor OH
Active caries
Poor motivation
Good dietary control - avoid hard/sticky foods, restrict sugars and acids

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6
Q

What are risks of fixed appliances?

A

Decalcification
Root resorption
Loss of periodontal support
TMJ dysfunction
Failed tx & relapse
Reversible risks - pain, ulcerations etc

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7
Q

What are the 2 types of fixed attachments ?

A

Bands
Bonds/brackets

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8
Q

When would bands be placed instead of brackets?

A

Usually on molars or premolars or teeth with ceramic crowns

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9
Q

What is pre-adjusted edgewise fixed appliance?

A

One we use - slot, base and tie wing
Built in adjustments for individual teeth

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10
Q

What are standard edgewise brackets?

A

Brackets that require arch wire bends to produce ideal tip

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11
Q

What are the 3 phases of active treatment?

A

Levelling and aligning
Major tooth movement - correction of overjet and overbite, space closure, centre line correction
Finishing - detailed alignment

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12
Q

Describe the alignment phase? (Wires etc)

A

Light flexible arch wires, changed each visit
Wires of increasing stiffness
Deformation energy dissipates as wires straighten and pull teeth into alignment
Each new wire is deformed less but has higher deformation energy

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13
Q

What are the properties of NiTi wires

A

High flexibliity
Deliver a low force over a long range
Shape memory

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14
Q

What is used for major tooth movements?

A

Stainless steel wires

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15
Q

What are sliding mechanics?

A

When teeth are pushed or pulled along the arch wire by:
- power chain
- coil springs
- elastic bands

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16
Q

What metals are in SS wires?

A

Iron
Chromium
Nickel

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17
Q

What are the properties of SS wires?

A

Stiff
Resist deformation
Supports teeth as they move along the wire while closing space

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18
Q

What is used during finishing stage?

A

Lighter wires to allow occlusal setting
Fine adjustments to bracket position
Bends to arch wire
Elastics

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19
Q

What are the active components of removable appliances?

A

Springs
Biteplanes
Screws
Bows

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20
Q

What are the passive components of URA’s?

A

Retainers - e.g. Hawley

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21
Q

What are the different types of URA?

A

Interceptive appliance
Space maintainer
Pre-surgical orthopaedics (cleft care)
Active plate
Retainer
Functional appliance

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22
Q

What are the advantages of URA’s?

A

Can be removed for OH and sports
Increased anchorage
Easy to adjust
Less iatrogenic damage
Baseplate can be modified
Good at moving blocks of teeth
Passive if needed
Cheaper

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23
Q

What are the disadvantages of URAs?

A

Need good pt compliance
Limited movements - tipping
Affects speech
Technician required
Lower appliances difficult to tolerate
Inefficient at multiple tooth movements

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24
Q

What size are springs wire on URA?

A

0.5mm for single tooth
0.7mm for groups of teeth

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25
Q

What are springs made of on URA?

A

18/8 austenitic stainless steel

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26
Q

what force should be applied by springs for single tooth movement?

A

25 - 40 grams per tooth

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27
Q

where should a spring be placed on a tooth?

A

close to the gingival margin to reduce tupping tendency to minimum

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28
Q

give 4 examples of springs for URA

A

palatal finger springs
buccal canine retractors
z springs
t springs

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29
Q

what 2 movements can screws in baseplate make?

A

expansion
distilisation

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30
Q

how much seperation does 1/4 turn of a screw cause?

A

0.25mm

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31
Q

what are the disadvantages of screws?

A

bulky
expensive

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32
Q

what claps can be used for retention?

A

Adam’s or delta cribs - molars and premolars
Southend and C clasps - incisors
Ball hooks - interdental embrasure

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33
Q

what size/material are adams/delta cribs?

A

molars - 0.7mm ss round wire
premolar/deciduous - 0.6mm

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34
Q

what size/material are southend clasps?

A

0.6 or 0.7mm wire

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35
Q

what size/material are ball hooks?

A

0.7mm wire with soldered ball on end

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36
Q

how do adams clasps work?

A

engage undercuts at the mesial and distal corners of the edges
should engage 1mm of undercut

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37
Q

describe anchorage

A

for every action there is an equal and opposite reaction
resistance to unwanted tooth movement

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38
Q

how can we reinforce anchorage with URAs?

A

clasp more teeth
move only 1 or 2 teeth at a time
use lighter forces
occlusal capping
add headgear

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39
Q

how does a baseplate support anchorage?

A

palatal coverage

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40
Q

are baseplates active or passive?

A

can be both

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41
Q

what details should you give the lab for URA construction?

A

what appliance is for
retention components
active components
baseplate modifications
drawing of design

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42
Q

what would you see in the mouth if pt is wearing URA?

A

palatal mucosa should have indentation or redness

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43
Q

what would you look for in review appt of URA?

A

slightly mobile teeth if movement is occurring
if teeth are not moving, look for a cause (acrylic in the way, insufficient activation of springs, unerupted teeth, retained roots)

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44
Q

what should be done to URA at review appts?

A

reactivated 1-2mm and tighten cribs

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45
Q

how much tooth movement should occur each month with a URA?

A

1mm

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46
Q

why is it necessary to reduce the overbite before reducing the overjet?

A

as incisors tip, the lower incisors prevet further overjet reduction due to increasing overbite

47
Q

what can be added to URA to allow overjet to be reduced without increasing the overbite?

A

anterior bite plane

48
Q

what type of bone formation leads to formation of maxilla and mandible?

A

intra membranous

49
Q

describe intra membranous bone formation

A

mesenchymal cells - differentiation- osteoblasts - calcification = bone

50
Q

what type of bone formation makes condylar cartilage and nasal septum cartilage?

A

endo chondral

51
Q

describe endochondral bone formation

A

cartilage cells - hypertrophy - calcified matrix - osteogenic invasion = bone

52
Q

describe growth of the mandible

A

area on condensation above ventral part of developing mandible
develops in cone shaped cartilage
migrates inferior & fuses with mandibular ramus
cone shaped cartilage replaced by bone but upper end persists acting as growth cartilage

53
Q

describe development of the maxilla

A

remodelling - deposition and resorption occurring on opposite ends
progressively changes the size of whole bone
sequentially relocate each component of the whole bone

54
Q

how do functional appliances work?

A

stretch muscles of mastication
posture mandible
differential tooth eruption

55
Q

what are the skeletal effects of functional appliances?

A

places a backwards force on the maxillary arch
accelerates condylar growth
redirects condylar growth

56
Q

what are the dentoalveolar effects from functional appliances?

A

retracts upper teeth
proclines lower teeth
different rates of tooth eruption

57
Q

when are functional appliances most effective?

A

best success in:
mild to moderate increase in overjet (upto 11mm)
increase in overbite
active facial growth
willingness to comply

58
Q

what are the indications for functional appliances?

A

motivated patient
pre-adolescent growth phase
skeletal discrepancy mild to moderate
increased overjet/overbite (if class ii)
proclined maxillary incisors (if class ii)
well aligned arches

59
Q

what are contra-indications for functional appliances?

A

poor motivation
age >14
poor dental health
condylar disease (juvenile rheumatoid arthritis)
proclined lower incisors

60
Q

what are advantages of functional appliances?

A

removable (easy to clean)
may avoid extractions
accelerates skeletal growth
reduces incidence of trauma
early treatment
economical
less damage to tooth tissue

61
Q

what tooth tissue damage is reduced with functional appliances?

A

root resorption
chance of decalcification
effect on bone levels

62
Q

what are disadvantages of functional appliances?

A

compliance
lack of detailed tooth movements
candidosis with removable appliances

63
Q

when would only a functional appliance be used?

A

skeletal class ii cases with aligned arches

64
Q

when would you use functional and fixed appliance?

A

skeletal class ii plus irregularity/crowding

65
Q

how do you assess if a pt needs treatment?

A

clinical judgement
iotn

66
Q

how do you assess if the pt wants treatment?

A

motivation
cooperation

67
Q

how do you assess if its the right time for tx?

A

dental stage
growth
motivation

68
Q

how do you assess what type of tx is needed?

A

visualise tooth movements required
space analysis
appliance type

69
Q

what sources of space are there?

A

extractions
increased arch length
increased arch width
interproximal reduction

70
Q

what space requirements need extractions?

A

0-4mm = non-extraction
4-8mm = borderline
8+mm = extractions

71
Q

How would you decide for XLA in borderline cases?

A

Side profile
Skeletal pattern
Class I div 2
MH

72
Q

Why are premolars favourite choice of XLA for ortho?

A

No aesthetic impact on smile
Space near to crowding
Straight forward XLA
Molars good anchorage

73
Q

When would you extract 4’s?

A

When most space required
When canines are crowded

74
Q

When would you extract 5’s

A

When less anterior crowding
Allows molars to move forward

75
Q

Why are 6’s not routines extracted for ortho

A

Hard xla
Provides little space anteriorly
Long tx

76
Q

When would you choose to extract the 6’s

A

When poor quality - caries/large restorations

77
Q

When would you extract 1 lower incisor

A

Class 3 malocclusion
Lower incisor crowding
Severe rotation
Severe displacement

78
Q

When would uppers 2s be extracted

A

Very palatally displaced
Trauma
Contra lateral tooth congenitally absent/peg
Canine has good shape/size/colour

79
Q

When would upper 3’s be extracted

A

Ectopic
Only when upper 4 is in good position

80
Q

When would upper 1’s be extracted

A

Trauma
Dilaceration
Ectopic

81
Q

Why are lower 3’s a bad choice for xla

A

Poor contact point 2-4 leads to long term perio problems

82
Q

What non-orthodontic factors are considered when planning XLA cases

A

Tooth quality - hyperplasticity
Pathology - caries/pulp path/perio
Congenitally absent teeth
Abnormal shape
Difficult XLA

83
Q

What is considered when choosing retention regimen?

A

Likely stability of result
Initial malocclusion
OH
Compliance
Pt preference

84
Q

Name 3 types of retainer

A

Vacuum/pressure formed (VFR/PFR) - Essix
Hawley
Bonded (DBR)

85
Q

What is the role of GDP in ortho work

A

Identify - exam/refer/IOTN

Maintain OH
Ortho first aid
Retention

86
Q

What would you include in an ortho referral letter

A

Urgency
Suitability of pt
Whether malocclusion is suitable for tx by particular orthodontist/practice (IOTN)
Pt details
Reason & complaint
MH
OH levels
Trauma
SH
Motivation
Summary of malocclusion

87
Q

What order do lower permanent teeth erupt

A

6, 1, 2, 3, 4, 5, 7, 8

88
Q

What order do upper teeth erupt

A

6, 1, 2, 4, 5, 3, 7, 8

89
Q

Do upper or lower teeth erupt first

A

Lowers except 5’s

90
Q

What distance is usually required between the distal of 2 and mesial of 6 to prevent crowding

A

22mm

91
Q

Name 4 abnormalities in tooth formation

A

Crown root dilaceration
Supernumeraries
Peg shaped laterals
Hypodontia

92
Q

What is crown root dilaceration

A

Trauma causes displacement of unerupted permanent crown and root formation continues in a different direction

93
Q

What usually causes dilaceration

A

Trauma in deciduous dentition

94
Q

What do peg laterals increase risk of

A

Ectopic canines

95
Q

What teeth are most commonly missing in hypodontia

A

Upper 2s
Lower 5s

96
Q

How does hypodontia present

A

Delayed exfoliation of deciduous teeth
Delayed eruption of permanent teeth

97
Q

What can cause abnormalities in eruption and exfoliation

A

Eruption cyst
Impacted teeth
Infra-occluded deciduous teeth
retained deciduous
Cross bites in the mixed dentition

98
Q

How do eruption cysts appear

A

Blue mucosa over unerupted teeth

99
Q

What teeth are eruption cysts most common with

A

E’s and 6’s

100
Q

name 4 causes of impacted teeth

A

obstruction (supernumerary)
primary failure of eruption
insufficient space
ectopic teeth

101
Q

what causes infraoccluded deciduous teeth

A

ankylosis
adjacent teeth erupt and ankylosed teeth remain unchanged vertically - gives appearance of submerging

102
Q

what can cause premature loss of deciduous teeth

A

caries
balancing and compensating extractions
trauma

103
Q

what trauma can result in a centre line shift in incisors

A

avulsion

104
Q

when would you use balancing extraction

A

if concerned will cause a centre line shift during eruption of the permanent incisors

105
Q

what primary teeth extraction are more likely to cause a centreline shift

A

Cs and Ds

106
Q

when are compensating extractions usually done

A

lower 6’s so compensate with upper 6
prevent overeruption

107
Q

what can cross bites cause

A

displacement-tooth and jaw
tooth wear
easily corrected in mixed dentition

108
Q

what is optimum age for 6 XLA

A

9-10

109
Q

what does thumb sucking cause

A

proclined upper anteriors
retroclined lower incisors
buccal segment crossbites
reduced overbite or anterior open bite

110
Q

what are some management techniques for digit sucking

A

deterrent devices/habit breakers
elastoplast on finger
encouragement
nail varnish

111
Q

what % 6 year olds have midline diastema

A

98%

112
Q

what size diastema doesnt require tx

A

<3mm

113
Q

what would be tx of choice for large diastema

A

fixed appliances

Module 8 (7 decks)

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