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BDS3 Orthodontics > Lab techniques (3, 4, 5) > Flashcards

Lab techniques (3, 4, 5) Flashcards

1
Q

URA

A

upper removable appliance

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2
Q

retract

A

move distal

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3
Q

space created by (2)

A

extraction

widen arch

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4
Q

overjet

A

horizontal

risk of trauma, function impaired, aesthetics, lip trap

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5
Q

overbite

A

vertical

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6
Q

anchorage

A

balance of forces

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7
Q

anchorage needed for 2 teeth movement

A

base plate sufficient

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8
Q

extension of base plate

A

is 7 erupted fully - half length of 7s

not all the way back to hard-soft palte - gag reflex issue (stronger in younger pt)

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9
Q

is overjet increases during tx - indicates

A

anchorage issue

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10
Q

southend clasp

A

anterior retention

engage undercut

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11
Q

components of palatal finger springs (4)

A

Zig zag tag embedded into acrylic

Coils – force exerted

Active arm – long arm around canine,

Goal post – guard – underneath the wire – allow active arm to slide along palate without rubbing – guideplane

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12
Q

posterior rentention classically by

A

adam’s clasp on 6s

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13
Q

9 advantages of removable orthodontics

A
  • Tipping movement
  • Anchorage – large baseplate
  • Cheaper than fixed
  • Shorter chairside time needed
  • Good oral hygiene maintenance
  • Non-destructive to tooth – no need to prep, no etch
  • Less specialised training required to manage
  • Can be easily adapted for overbite reduction
  • Can achieve block movements
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14
Q

5 disadvantages of removable orthodontics

A
  • Less precise control of tooth movement – cannot 3D movement - extrude, intrude tooth, keep angulation but move in palate
  • Can be easily removed by the pt - only work when in the mouth
  • Generally 1-2 teeth can be moved at one time – don’t want to compromise the anchorage
  • Specialist technical staff required to construct the appliances
  • Rotation very difficult to correct
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15
Q

how do teeth move in orthodontics

A

The force exerted creates pressure this causes the bone around the tooth to be remodel

  • Remodelling - process where a bone is selectively removed in some areas and added in others

controlled by the periodontal ligaments or fibres (PDL) the PDL is a collection of fibres surrounding the root which act as a buffer against shock

  • PDL shock
    • Osteoclasts and osteoblasts activated
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16
Q

aim for

Retract canine (1st premolars extracted already), 6mm overjet (OJ), Reduce overbite (OB)

A

please construct URA to retract 13 + 23 and reduce overbite (OB)

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17
Q

ARAB for

Aim - please construct URA to retract 13 + 23 and reduce overbite (OB)

A

A – 13+23 palatal finger springs and guards, 0.5mm HSSW

R – same

A – same only moving 2 teeth

B - self cure PMMA

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18
Q

overbite tackled in URA how

A

base plate modification - flat anterior bite plane (FABP) OJ + 3mm

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19
Q

why can you not move all anteriors at one (if need to move 3-3)

A

compromise anchorage

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20
Q

FABP use

A

overbite

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21
Q

how to FABP reduce overbite

A

Lowers inhibit anteriors coming back

  • don’t bend teeth need to change whole angulation

Lower anteriors bite against the platform

  • Creates space/ posterior open bite
  • posteriors will want to continue to erupt to continue being in occlusion
    • still want bone and soft tissue around them
      • lowers come up, upper do not as of appliance

Only works in young as bone form around

  • otherwise roots get exposed = sensitive, unaesthetic, unstable
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22
Q

why is FABP OJ + 3mm

A

negative - bigger, bulkier, more invasice, less well tolerated by pt

but if not

Pt will retrude jaw – go inadvertently behind biteplane

  • Retrocline lowers so increase overjet
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23
Q

11 uses of study casts

A
  • Look back on treatment to show pt changes – progress
  • Teaching purposes
  • Pt motivate – where you have been and going
  • Design appliance on it
  • Study pt occlusion outwith pt presence – diagnosis
  • Legal reasons
  • Forensics
  • Explaining treatment to pt
  • Second opinion
  • Retrospective studies
  • Consent decision by pt more informed
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24
Q

retentive

A

resist displacement forces

go into undercuts

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25
Q

3 retentive components

A

adam’s clasp

southend clasp

labial bows

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26
Q

wire gauge for retentive components

A

0.7mm HSSW (permanent teeth)

0.6mm HSSW (primary teeth)

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27
Q

palatal acitve components (4)

A

finger springs + guard

Z-spring (double cantilever)

flapper spring

T-spring

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28
Q

palatal active components location

A

in palate - have acrylic over them - well protected

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29
Q

wire gauge for palatal active components

A

0.5mm HSSW

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30
Q

2 buccal active components

A

buccal canine retractor

roberts retractor

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31
Q

wire gauge and explanation for buccal active components

A

0.5mm HSSW; 0.5mm I.D. tubing

easily distorted so add sheating on top to increase strength and rigidity

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32
Q

stops role

A

passive

prevents relapse after active movement (mesial drift)

DOESN’T RESIST DISPLACEMENT FORCES

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33
Q

wire gauge for stops

A

0.7mm HSSW (flattened)

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34
Q

this is

A

adam’s clasp

0.7mm HSSW (0.6mm on deciduous teeth)

retentive

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35
Q

this is

A

southend clasp

0.7mm HSSW

retentive

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36
Q

this is

A

labial bow

0.7mm HSSW

retentive

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37
Q

buccal retactors (active component) wire

A

mesial aspect is thinner than distal aspect as distal aspect as 0.5mm I.D. tubing to protect it from being deformed

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38
Q

this is

A

finger spring + guard

0.5mm HSSW

active

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39
Q

this is

A

z sping

0.5mm HSSW

active

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40
Q

this is

A

flapper spring

0.5mm HSSW

active

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41
Q

this is

A

T spring

0.5mm HSSW
active

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42
Q

this is

A

buccal canine retractor

0.5mm HSSW; 0.5mm I.D. tubing

active

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43
Q

this is

A

roberts retractor

0.5mm HSSW; 0.5mm I.D. tubing

active

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44
Q

fitting a URA

10 stages

A

Disinfected ready to fit – in passive state

  1. Ensure the pt details match the details supplied for the appliance
    * Check – right appliance for right pt
  2. Check the appliance matches the design specifications – human errors
  3. Inspect the appliance and run your finger over all surfaces looking for sharp or potentially traumatic areas
  4. Check the integrity of wirework
  5. insert the appliance into the pt mouth, immediately looking for areas of blanching or soft tissue trauma – pain, stop wearing it
  6. check the posterior retention (Adam’s clasp)
    * firstly flyovers, then arrowheads are correctly engaging the appropriate undercuts
  7. apply the same principles to the anterior retention
  8. activate the appliance (1mm movement approx. per month)
  9. demonstrate to pt the correct procedure for insertion and removal of the appliance
    * ensure that the pt demonstrates this correctly
  10. book a review appointment 4-6weeks (need to reactivate the active component - 1mm movement done)
45
Q

what to check wirework for

A

damage or work hardening

  • bend one way than other – no flexibility = snaps on movement
  • through trimming stage – easier to spot areas of damage – different diamete
  • shine from chromium and prevents corrosion
    • lost on damage = corrode (black area), break
46
Q

aim for URA if want to

retract buccal placed canines, 1st premolars extracted, 6mm (OJ), reduce (OB)

A

aim - please construct a URA to retract buccally placed 13 + 23 and reduce OB

47
Q

active component for

aim - please construct a URA to retract buccally placed 13 + 23 and reduce OB

A

13+23 buccal canine retractor, 0.5mm HSSW and 0.5mm ID tubing

  • two lines (highlight tubing)
  • wirework distal to premolar so not inhibited in area

finger spring only distal but need distal and palatal to get in line of arch

48
Q

retentive component for

aim - please construct a URA to retract buccally placed 13 + 23 and reduce OB

A

16 + 26 Adam’s clasp; 0.7mm HSSW

11 +21 Southend clasp; 0.7mm HSSW

49
Q

anchorage for

aim - please construct a URA to retract buccally placed 13 + 23 and reduce OB

A

good as only moving 2 teeth

50
Q

baseplate for

aim - please construct a URA to retract buccally placed 13 + 23 and reduce OB

A

self cure PMMA

with Flat anterior bite plane OJ + 3mm

51
Q

where to draw extension of base plate to

A

if 7s erupted

extend half away across 7s

52
Q

when to use a palatal finger spring and guard or buccal canine retractor

A

Palatal finger spring – canines in line of arch

Buccal canine retractors – to move back and in line

53
Q

10 points pt information and intructions for URA

A
  1. appliance will feel big and bulky (this is normal, and they will get used to it quickly)
  2. may causes initial excessive salivation (this will pass in 24 hours – normal)
  3. may impinge speech for a short period of time (practise reading a book aloud at home and this will subside – don’t want them to be teased)
  4. may cause initial discomfort or ache or pressure (this is normal, and indicates that the appliance is working)
  5. to be worn 24/7 including meal times and sleep - using masticatory forces to advantages
  6. remove after every meal and clean with a soft brush (warm water and soap)
  7. remove and store in a protective container when participating in contact or active sport (sharp intake of breath - running, swimming)
  8. avoid hard or sticky foods that may damage the appliance and be cautious with hot food and drinks
  9. not feel initial heat – appliance is insulator – not feel until to get to back of throat
  10. missing appointment and non-compliance will significantly lengthen treatment time
  11. provide emergency contact details in case any problems arise
54
Q

issue of anterior crossbite (2)

A

aesthetics - dark hole due to light refraction

self concious

55
Q

aim for appliance if 12 in anteiror cross bite

A

please construct a URA to correct an anterior crossbite on 12

56
Q

active component for

Aim – please construct a URA to correct an anterior crossbite on 12

A

12 Z-spring, 0.5mm HSSW

(double coils a.k.a double cantilever spring; large amount of displacement force)

57
Q

rententive for

Aim – please construct a URA to correct an anterior crossbite on 12

A

16+26 Adam’s clasp, 0.7mm HSSW

14+24 Adam’s clasp, 0.7mm HSSW

58
Q

anchorage for

Aim – please construct a URA to correct an anterior crossbite on 12

A

good only one tooth moving

59
Q

baseplate for

Aim – please construct a URA to correct an anterior crossbite on 12

A

Self cure PMMA

Posterior bite plane

60
Q

why need for posterior bite plane in tx anterior Xbite

A
  • Lower teeth will prevent the 12 moving forward
    • create a temporary anterior open bite to allow tooth to move forward without obstruction
  • incorporate all teeth prevent continuing to erupt

Overjet from Z spring

Natural retention from lowers

61
Q

why do anterior teeth not over erupt in posterior bite plane use

A

Anterior teeth don’t occlude naturally together in humans

(unlike rabbis and rodents – continue to erupt – need to continue to gnaw to prevent not being able to open)

62
Q

restorative use of posteiror bite planes

A

clinicians posterior bite planes to allow continued eruption to anterior teeth

  • E.g. not reached maximum eruption level
63
Q

Z spring can do

A

small amounts of rotation in URA

Helpful to get into line of arch when fixing anterior cross bite – protrude and rotate

  • Straight forward – activate both coils equally
  • Rotate to left = activate left coil more
  • rotate to right = activate right coil more

move forward on a twist - like door

64
Q

first step in drawing URA design

A

cross out teeth to be extracted/missing

65
Q

buccal canine retractor distal placement

A

place as far back as you want canine to move to (e.g. mesial 5)

66
Q

coil for active components

A

need to be on mesial aspect

so does the guard for finger springs

67
Q

mesial stops

A

mesial aspect canines – naturally want to relapse

Stops are passive

  • no active force applied
  • do not resist displacement forces (not retention)
  • not anchorage or baseplate (prevents drift forward)

Flattened – so not taking up a large amount of space

68
Q

robert’s retractor

A

Active component

  • But positioned in upper anterior undercut so resist displacement forces (by product)

Only use when have proclined upper anterior teeth

69
Q

retention for URA with robert’s retractor

A

16+26 Adam’s Clasp; 0.7mm HSSW

  • Cannot place southend*
  • interfere with active components and fixate them where they are so prevent the active component action
  • but have anterior retention as by-product of roberts retractor*
70
Q

anchorage discuss for this URA

A

moving more than 2 teeth here (as 4)

  • not perfect but can get away as 4 anterior as 4 shortest rooted teeth in upper arch so have posterior teeth and baseplate
71
Q

how to continue to reduce OB

A

When bringing canines back by applying actual active force move quicker than teeth naturally eruptingposterior teeth

  • new bone is soft needs to thicken

so if remove FABP at once then when bite down relapse as teeth sink back in

  • Take a small amount FABP anteriorly away in small increments
    • Trim at a slant to follow the shape of the tooth

Lower teeth wont get stuck as less likely to lower jaw forward

  • Moves backward naturally
72
Q

why can a posterior bite plane not be used to continue to reduce OB

A

no use as relapse in few weeks as lowers press force on upper anterior as space posteriorly jaw want to resolve

  • Drop down when takeout bite plane
    • lower teeth contact above cingulum – relapse

URA get tipping or tilting

  • So incisal edge of upper will lower when moving back – increases OB

Need to continue to reduce OB whilst moving anterior back

73
Q

when may want to expand upper arch

A

to create space e.g. posterior cross bites

74
Q

aim for expanding upper arch as posteiror cross bite

A

Aim – please a construct a URA to expand the upper arch

75
Q

active component for

expand upper arch

A

midline palatal screw

76
Q

retention for

expand upper arch

A

16 + 26 adams clasps; 0.7mm HSSW

14+ 24 adams clasps; 0.7mm HSSW (if deciduous 0.6mmm)

77
Q

anchorage for

expand upper arch

A

reciprocal

78
Q

reciprocal anchorage

A

Force equal on both sides – newtons 3rd law

To cancel out force need counteract the force in the other way

79
Q

reciprocation in RPD

A

force on one side, reciprocal side arm to prevent unwanted tooth movement

80
Q

baseplate for expansion upper arch

A

Self cure PMMA

  • Needs cut in half down midline around screw
  • Only held together by screw

posterior bite plane

81
Q

lingual cross bites

A

posterior teeth biting on inside lowers instead of outside

82
Q

problem with occlusion when expanding upper arch in post Xbite

A

Cusp to cusp – cuspal interference

  • Inhibit movement of uppers
    • Lowers can expand to – dragged with uppers

Want to relieve interference between uppers and lowers

  • Posterior bite plane
    • Must include all posterior teeth – so none continue to erupt

Not flat anterior bite plane – posterior teeth continue to erupt

  • only used for overbite
83
Q

posterior bite plane

A

relieve occlusal interference of uppers and lowers when expanding upper arch

must include all posterior teeth so none continue to erupt

84
Q

flat anterior bite plane

A

posteiror teeth will continue to erupt

only used for OVERBITE

85
Q

midline palatal screw relies on

A

Need pt compliance

  • Demo to them and they demo them back to you

1 turn a week ->0.25mm a week (1mm a month)

  • move teeth with osteoclastic and osteoblastic action around teeth
86
Q

rapid maxillary expansion

A

similar but bonded onto teeth (turn couple times a day), fracture the midline suture

not tooth movement

87
Q

why is diastema not created in upper arch expansion

A

Usually have cross over crowding so won’t get diastema

  • give space to move teeth into correct alignment
88
Q

modification for device if only expanding one quadrant i.e. unilateral posterior cross bite

A

cut different - emphasise effect on that quadrant

minimal expansion on other side

can’t move screw greatly due to curvature of the mouth

89
Q

modification if dont want to expand anterior teeth region only posterior teeth region

A

remove base plate in anterior region

  • cut distal to canines
90
Q

wire bending

A

Hold pliers in dominate hand

  • Counteract to straighten with pinch finger down
  • Bend away from face and others

Cut with wire cutters – hold onto both ends to prevent ping away

91
Q

adam’s clasp components (5)

A

Bridge – buccal away, lift in and out

Arrowheads – engage undercut, functional part

Flyover – between teeth so not interfering with occlusion

Leg – 0.5-1mm between palate and wire– inside baseplate – completely encompassed

Tag – 0.5mm to prevent slippage (mesial direction for distal leg to prevent sticking out back of baseplate)

92
Q

aim for wire after manipulation

A

Shine

  • chromium – needed – resistance to corrosion

Want minimal bends

  • metal fatigue or work hardened
93
Q

bridge of adam’s clasp

A

buccal away, lift in and out

94
Q

arrowheads of adam’s clasp

A

engage undercut, fuctional part

95
Q

flyover

A

between teeth so not interfering with occlusion

96
Q

leg of adam’s clasp

A

0.5-1mm between palate and it

so inside baseplate - completely encompassed

97
Q

tag of adam’s clasp

A

0.5mm to prevent slippage

(mesial direction for distal leg to prevent sticking out baseplate)

98
Q

pro and con of digitised study casts

A

can be shared easily

not same feel for occlusion - used as addition not replacement

99
Q

2 cons of physical study models

A

storage - need 12 years for legal

damage - fracture, attrition - render useless

100
Q

12 uses of study casts

A
  • Before and after treatment
  • Medicolegal records
  • Second opinions
  • Study occlusion when pt not there
  • Teaching
  • Motivation
  • Forensics
  • Legal reasons - 10-12 years
  • Tx planning
  • Waxing up
  • Diagnosis
  • More informed decision for pt
  • Retrospective studies
101
Q

stainless steel 5 elements

A

iron

chromium

titanium

carbon

nickel

102
Q

% iron in stainless steel

A

72

103
Q

% chromium in stainless steel

A

18

104
Q

% titanium in stainless steel

A

1.7

105
Q

% carbon in stainless steel

A

0.3

106
Q

% nickel in stainless steel

A

8

107
Q

this is

A

adam number 64 pliers

108
Q

this is

A

adam number 65 pliers

109
Q

this is

A

wire cutters

BDS3 Orthodontics (13 decks)

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