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Module 8 > Ortho > Flashcards

Ortho Flashcards

(113 cards)

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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
What are springs made of on URA?
18/8 austenitic stainless steel
26
what force should be applied by springs for single tooth movement?
25 - 40 grams per tooth
27
where should a spring be placed on a tooth?
close to the gingival margin to reduce tupping tendency to minimum
28
give 4 examples of springs for URA
palatal finger springs buccal canine retractors z springs t springs
29
what 2 movements can screws in baseplate make?
expansion distilisation
30
how much seperation does 1/4 turn of a screw cause?
0.25mm
31
what are the disadvantages of screws?
bulky expensive
32
what claps can be used for retention?
Adam's or delta cribs - molars and premolars Southend and C clasps - incisors Ball hooks - interdental embrasure
33
what size/material are adams/delta cribs?
molars - 0.7mm ss round wire premolar/deciduous - 0.6mm
34
what size/material are southend clasps?
0.6 or 0.7mm wire
35
what size/material are ball hooks?
0.7mm wire with soldered ball on end
36
how do adams clasps work?
engage undercuts at the mesial and distal corners of the edges should engage 1mm of undercut
37
describe anchorage
for every action there is an equal and opposite reaction resistance to unwanted tooth movement
38
how can we reinforce anchorage with URAs?
clasp more teeth move only 1 or 2 teeth at a time use lighter forces occlusal capping add headgear
39
how does a baseplate support anchorage?
palatal coverage
40
are baseplates active or passive?
can be both
41
what details should you give the lab for URA construction?
what appliance is for retention components active components baseplate modifications drawing of design
42
what would you see in the mouth if pt is wearing URA?
palatal mucosa should have indentation or redness
43
what would you look for in review appt of URA?
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)
44
what should be done to URA at review appts?
reactivated 1-2mm and tighten cribs
45
how much tooth movement should occur each month with a URA?
1mm
46
why is it necessary to reduce the overbite before reducing the overjet?
as incisors tip, the lower incisors prevet further overjet reduction due to increasing overbite
47
what can be added to URA to allow overjet to be reduced without increasing the overbite?
anterior bite plane
48
what type of bone formation leads to formation of maxilla and mandible?
intra membranous
49
describe intra membranous bone formation
mesenchymal cells - differentiation- osteoblasts - calcification = bone
50
what type of bone formation makes condylar cartilage and nasal septum cartilage?
endo chondral
51
describe endochondral bone formation
cartilage cells - hypertrophy - calcified matrix - osteogenic invasion = bone
52
describe growth of the mandible
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
describe development of the maxilla
remodelling - deposition and resorption occurring on opposite ends progressively changes the size of whole bone sequentially relocate each component of the whole bone
54
how do functional appliances work?
stretch muscles of mastication posture mandible differential tooth eruption
55
what are the skeletal effects of functional appliances?
places a backwards force on the maxillary arch accelerates condylar growth redirects condylar growth
56
what are the dentoalveolar effects from functional appliances?
retracts upper teeth proclines lower teeth different rates of tooth eruption
57
when are functional appliances most effective?
best success in: mild to moderate increase in overjet (upto 11mm) increase in overbite active facial growth willingness to comply
58
what are the indications for functional appliances?
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
what are contra-indications for functional appliances?
poor motivation age >14 poor dental health condylar disease (juvenile rheumatoid arthritis) proclined lower incisors
60
what are advantages of functional appliances?
removable (easy to clean) may avoid extractions accelerates skeletal growth reduces incidence of trauma early treatment economical less damage to tooth tissue
61
what tooth tissue damage is reduced with functional appliances?
root resorption chance of decalcification effect on bone levels
62
what are disadvantages of functional appliances?
compliance lack of detailed tooth movements candidosis with removable appliances
63
when would only a functional appliance be used?
skeletal class ii cases with aligned arches
64
when would you use functional and fixed appliance?
skeletal class ii plus irregularity/crowding
65
how do you assess if a pt needs treatment?
clinical judgement iotn
66
how do you assess if the pt wants treatment?
motivation cooperation
67
how do you assess if its the right time for tx?
dental stage growth motivation
68
how do you assess what type of tx is needed?
visualise tooth movements required space analysis appliance type
69
what sources of space are there?
extractions increased arch length increased arch width interproximal reduction
70
what space requirements need extractions?
0-4mm = non-extraction 4-8mm = borderline 8+mm = extractions
71
How would you decide for XLA in borderline cases?
Side profile Skeletal pattern Class I div 2 MH
72
Why are premolars favourite choice of XLA for ortho?
No aesthetic impact on smile Space near to crowding Straight forward XLA Molars good anchorage
73
When would you extract 4’s?
When most space required When canines are crowded
74
When would you extract 5’s
When less anterior crowding Allows molars to move forward
75
Why are 6’s not routines extracted for ortho
Hard xla Provides little space anteriorly Long tx
76
When would you choose to extract the 6’s
When poor quality - caries/large restorations
77
When would you extract 1 lower incisor
Class 3 malocclusion Lower incisor crowding Severe rotation Severe displacement
78
When would uppers 2s be extracted
Very palatally displaced Trauma Contra lateral tooth congenitally absent/peg Canine has good shape/size/colour
79
When would upper 3’s be extracted
Ectopic Only when upper 4 is in good position
80
When would upper 1’s be extracted
Trauma Dilaceration Ectopic
81
Why are lower 3’s a bad choice for xla
Poor contact point 2-4 leads to long term perio problems
82
What non-orthodontic factors are considered when planning XLA cases
Tooth quality - hyperplasticity Pathology - caries/pulp path/perio Congenitally absent teeth Abnormal shape Difficult XLA
83
What is considered when choosing retention regimen?
Likely stability of result Initial malocclusion OH Compliance Pt preference
84
Name 3 types of retainer
Vacuum/pressure formed (VFR/PFR) - Essix Hawley Bonded (DBR)
85
What is the role of GDP in ortho work
Identify - exam/refer/IOTN Maintain OH Ortho first aid Retention
86
What would you include in an ortho referral letter
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
What order do lower permanent teeth erupt
6, 1, 2, 3, 4, 5, 7, 8
88
What order do upper teeth erupt
6, 1, 2, 4, 5, 3, 7, 8
89
Do upper or lower teeth erupt first
Lowers except 5’s
90
What distance is usually required between the distal of 2 and mesial of 6 to prevent crowding
22mm
91
Name 4 abnormalities in tooth formation
Crown root dilaceration Supernumeraries Peg shaped laterals Hypodontia
92
What is crown root dilaceration
Trauma causes displacement of unerupted permanent crown and root formation continues in a different direction
93
What usually causes dilaceration
Trauma in deciduous dentition
94
What do peg laterals increase risk of
Ectopic canines
95
What teeth are most commonly missing in hypodontia
Upper 2s Lower 5s
96
How does hypodontia present
Delayed exfoliation of deciduous teeth Delayed eruption of permanent teeth
97
What can cause abnormalities in eruption and exfoliation
Eruption cyst Impacted teeth Infra-occluded deciduous teeth retained deciduous Cross bites in the mixed dentition
98
How do eruption cysts appear
Blue mucosa over unerupted teeth
99
What teeth are eruption cysts most common with
E’s and 6’s
100
name 4 causes of impacted teeth
obstruction (supernumerary) primary failure of eruption insufficient space ectopic teeth
101
what causes infraoccluded deciduous teeth
ankylosis adjacent teeth erupt and ankylosed teeth remain unchanged vertically - gives appearance of submerging
102
what can cause premature loss of deciduous teeth
caries balancing and compensating extractions trauma
103
what trauma can result in a centre line shift in incisors
avulsion
104
when would you use balancing extraction
if concerned will cause a centre line shift during eruption of the permanent incisors
105
what primary teeth extraction are more likely to cause a centreline shift
Cs and Ds
106
when are compensating extractions usually done
lower 6's so compensate with upper 6 prevent overeruption
107
what can cross bites cause
displacement-tooth and jaw tooth wear easily corrected in mixed dentition
108
what is optimum age for 6 XLA
9-10
109
what does thumb sucking cause
proclined upper anteriors retroclined lower incisors buccal segment crossbites reduced overbite or anterior open bite
110
what are some management techniques for digit sucking
deterrent devices/habit breakers elastoplast on finger encouragement nail varnish
111
what % 6 year olds have midline diastema
98%
112
what size diastema doesnt require tx
<3mm
113
what would be tx of choice for large diastema
fixed appliances

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