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Dentistry BDS4 > Orthodontics > Flashcards

Orthodontics Flashcards

1
Q

When should you refer patient for orthodontic assessment?

A 
deciduous dentition - CLP, craniofacial abnormalities (if not under MDT care)
early mixed dentition - delayed eruption of perm incisors, impaction/FOE of 6s, poor prognosis of 6s, severe class 3, AXB, ectopic canines, pathology
late mixed dentition - growth mod in class 2, hypodontia, other routine problems
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2
Q

What is ideal occlusion?

A

anatomically perfect arrangement of teeth

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3
Q

what is normal occlusion?

A

acceptable variation from the ideal

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4
Q

what are competent lips?

A

lips meet with minimal or no muscle activity

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5
Q

what are incompetent lips?

A

evident muscle activity is needed to make lips meet

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6
Q

Class I incisor relationship

A

lower incisors occlude with or lie immediately below cingulum of upper incisors

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7
Q

Class II incisor relationship

A

lower incisor edges lie posterior to cingulum of upper incisors
div 1 - max centrals are upright or proclined, OJ increased
div 2 - max centrals retroclined, OJ usually decreased, may be increased

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8
Q

Class III incisor relationship

A

lower incisors lie anterior to cingulum of upper incisors, OJ is decreased or reversed

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9
Q

OJ and OB

A

OJ - distance between max and mand incisors in horizontal plane
OB - overlap of incisors in vertical plane

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10
Q

Complete vs incomplete OB

A

Complete - lower incisors contact upper incisors or palatal mucosa
incomplete - they dont

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11
Q

Anterior Open bite

A

no vertical overlap of incisors when the buccal segments are in contact

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12
Q

Crossbites

A

deviation from normal bucco-lingual relationship

  • lingual - buccal cusps of lower molars occlude lingually to lingual cusps of upper
  • buccal - buccal cusps of lower per/molars occlude buccally to buccal cusps of uppers
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13
Q

Dento-alveolar compensation

A

inclination of the teeth to compensate for underlying skeletal abnormalities

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14
Q

Why are study models taken?

A

clinical records, legal documents, show what could be achievable, show what has changed, show the final treatment position

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15
Q

What indices are used for assessing orthodontic need

A 
IOTN - 
grade 1 - minor malocclusions
grade 2 - minimal need
grade 3 - moderate need - use the aesthetic component
grade 4 - great need
grade 5 - very great

grade 4/5 get NHS treatment
grade 3 needs aesthetic component of 6+

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16
Q

How do you assess the dental health component?

A 
MOCDOO
Missing teeth
overjet
crossbite
displacement
overbite
other
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17
Q

What are the cephalometric points used in ortho assessment? and what are the common values

A 
Sella, nasion, orbitale, porion (EAM), anterior nasal spine, posterior nasal spine, gonion, menton, A point, B point
Frankfort plane = porion-orbitale
maxillary plane = PNS-ANS
mandibular plane = gonion - menton
SNA = 81 +/-3
SNB = 79 +/-3
ANB = 3 +/-2
Max = 109 +/-6
Mand = 93 +/- 6
MMPA  = 27 +/-4
facial proportion (LAFH) = 55
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18
Q

What are balancing extractions and compensating extractions?

A

balancing - extraction of same/adjacent tooth on the opposite side of the same arch - preserves symmetry
compensating - extract of occluding tooth on the opposing arch. stops over eruption

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19
Q

When do you extract FPM?

A

poor prognosis, need calcification of the furcation of the 7s as optimal.
if late - little space closure and 7 tilts mesially
if early - get crowding

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20
Q

What is a median diastema, what causes it and how to treat

A

Diastema - gap between central incisors. 6yo = 98%, 12yo = 7%
caused by small teeth, absent/peg laterals, midline discrepancy, proclination of ULS, physiological from pressure of developing teeth on roots, fraenum

treatment - wait. before 3s erupt and <3mm
after 3s - ortho Tx and retention.

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21
Q

Anchorage options for distal movement

A

temporary anchorage devices are preferred to headgear

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22
Q

How to treat buccally displaced max 3s

A

if crowded - XLA 4s and fixed applicances

ortho Tx - buccal canine retractor

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23
Q

How to treat impacted canines

A
  1. do nothing and monitor for pathology
  2. XLA 3s, restorative to close space (possible trauma from XLA, fixed treatment)
  3. open exposure of 3s, ortho Tx to pull down (only if in favourable position, takes a while, fixed Tx and requires good cooperation)
  4. autotransplantation - not always successful, can cause ankylosis/necrosis
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24
Q

Causes of increased OJ

A

Skeletal pattern, soft tissues, lip trap, habits, crowding

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25
Q

management of increased OJ

A

fixed appliances for class I and II to retract ULA, +/- XLA.
functional appliance in class II to tilt teeth/growth mod
ortho camouflage
surgical correction if severe

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26
Q

Causes of increased OB

A

normal is 1/2-1/3 overlap.
increased is associated with class II/2
only treat if traumatic.
decreased LFH, high lower lip, retroclined incisors, increased inter incisal angle

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27
Q

how to treat increased OB

A

FABP to allow molars to erupt

procline lower incisors

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28
Q

Cause of AOB

A

vertical growth > horizontal growth

habits, tongue thrust, iatrogenic, CLP

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29
Q

Treatment of AOB

A

cease habit, FPBP

30
Q

Treatment of reverse OJ

A
  1. Do nothing and accept
  2. camouflage
  3. surgery if ANB below -4
    lower incisal angle to mand plan <80
31
Q

How do you treat XB?

A

AXB - z spring and FPBP to disclude teeth

PXB - quad helix, RME, midline palatal screw and FPBP

32
Q

what are indications for removable appliances?

A 
Require movement of blocs of teeth (PXB)
interceptive treatment in mixed dentition (AXB)
overbite reduction
elimination of occlusal interferences
spacemaintainer when passive
retention when passive
habit deterrent
33
Q

What are the active components of removable appliances and what are they made out of

A

Z springs - 0.5mm HSSW
buccal canine retractor
roberts retractor
midline palatal screw

34
Q

What are the retentive components of removable appliances and what are they made out of?

A

Adams cribs - 0.7mm HSSW (0.6mm on deciduous)
southend clasp
labial bow

35
Q

What are the components of fixed orthodontic appliances?

A

Bands - on molars
Brackets - on each teeth, usually labial surfaces
Archwire - active component. NiTi or steel.
ligatures - elastic bands or wire to hold archwire in bracket
can have class II or class III inter arch bands

36
Q

What is the mode of action of functional appliances? and give an example of one

A

25% skeletal change, 75% dental tooth tipping

twin block appliance

37
Q

What information would you give a patient who has jsut been given their removable appliance?

A
  1. non compliance with significantly increase your treatment time
  2. it will feel big, you will salivate more and you will find it hard to talk. practice and these will aleviate
  3. wear is 24/7 except contact sports and swimming. clean after meals with toothbrush over filled sink
  4. if it breaks, come back
  5. some discomfort initially is to be expected - it means it is working. this will reduce
  6. emergency contact details
38
Q

How does a twin block appliance work?

A

retroclination of upper anteriors
proclination of lower anteriors
mid line palatal screw frequently incorportated to tip posterior teeth to correct PCB
re-positions mandible forward
reduces muscle action on jaws
some skeletal grown from secondary growth centres
correcting AOB with posterior bite planes and allows further eruption of anteriors

39
Q

What is dento-alveolar compensation?

A

a system which attempts to maintain normal inter arch relationships

can maintain occlusal relationship even though there are variations in growth and facial pattern

40
Q

What is a supernumerary tooth?

A

a tooth that is in addition to the regular dentition

41
Q

What are TADs and why are they used?

A 
temporary anchorage devices - mini implants to provide anchorage for ortho treatment
no osseointegration
easily placed
absolute anchorage
removable
patient compliance unnecessary
42
Q

Who is involved in treating a patient with class III malocclusion

A 
psychology
ortho
surgical
technologist
restorative
speech and language therapy
oral hygeine
43
Q

list the steps involved in class III malocclusion treatment

A 
tooth alignment, eliminating crowding/spaces and XB
coordination of the arches
decompensate incisors
flatten occlusal plane
surgical fixatoin
port surgery ortho
44
Q

What different orthognathic surgeries are carried out?

A

Le fort 1 osteotomy
ant max osteotomy
BSSO
genioplasty

45
Q

What are the risk/benefits you need to discuss with a patient who has carious 6s but wants ortho Tx?

A
  • removal of 6s, tipping of 7s, loss of bone, spaces
  • long term prognosis of 6s
  • LA/GA for Xn, risk of death if GA
  • risks of ortho Tx
46
Q

What are some risks of orthodontic treatment?

A
  • root resorption
  • relapse
  • failure to complete treatment
  • treatment failure
  • devitalising of tooth
  • pain
  • trauma from components
  • decalcification of tooth
47
Q

when would you treat an anterior open bite?

A

if mand displacement on closing
if traumatic
aesthetics

48
Q

What characteristics of a malocclusion would make it ideal for treatment with a URA

A
  • palatally tipped teeth
  • 1 or 2 teeth needing movement
  • class 1 molar relationship
  • space
49
Q

What are causes of ectopic canines?

A
  • ectopic crypt position
  • absent laterals
  • crowding
  • retention of deciduous canine
  • genetics
50
Q

How do you monitor the eruption of canines?

A

palpation from 9/10
look at inclination of 2s
mobility of cs
colour of cs

51
Q

What are the signs of impacted canines?

A
  • delayed eruption
  • retained Cs
  • unable to palpate
  • distal tipping of 2s
    loss of vitality or mobility of 1s/2s
52
Q

What are functions of a URA other than tipping teeth?

A
  • space maintainer
  • habit breaker
  • retainer
  • correct OB
53
Q

What warnings do you give someone on provision of a URA?

A
  • big and bulky
  • non compliance increases duration
  • will feel uncomfortable, saliva, speech - will settle
  • beware of hot drinks
54
Q

Waht instructions do you provide to somone when you have them a URA?

A
  • wear 24hs
  • remove for contact sport or swimming
  • clean after eating with soft brush and water
  • dont eat hard or sticky foods
55
Q

What do you use in a URA to correct an ACB and a PCB?

A

ACB - Z spring

PCB - midline palatal screw

56
Q

What are the signs of a digit sucking habit?

A 
narrow and high palate
PCB
AOB
ACB
increased OJ
proclined uppers/retroclined lowers
57
Q

What are risks of bonded and pressure formed retainers?

A

bonded:
can debond, caries, gingivitis, poor OH, fracture of wire

pressure:
lost/chewed by dog
compliance and no longer fitting, keeping clean

58
Q

How would you assess vertical skeletal relationship?

A

LAFH vs TFH - should be 50% ish

FMPA - should meet at the back of the head

59
Q

What special investigations would you do for a patient before referring them on to ortho?

A

study models and bite recording

lateral ceph -

60
Q

What are some causes of AOB?

A

digit sucking
tongue thrust
fracture of mandible
skeletal discrepancy

61
Q

How would you monitor canine movement?

A

measure, can use a definite point to compare against

62
Q

what are different types of orthodontic retention?

A

hawley retainer
vacuum formed retainer
fixed bonded retainer

63
Q

A patient with fixed ortho presents with white areas around the brackets, what could be the cause?

A
  • demineralisation
  • excess cements
  • plaque
64
Q

How does a URA affect the anterio-posterior skeletal relationship?

A

it doesnt

65
Q

How does a URA affect the vertical skeletal relationship?

A

FABP would decrease overbite and increased LAFH

66
Q

What would cause the failure of removal of infected material during RCT?

A

inadequate apical shaping
indadequate coronal flare
inadequate irrigation
apical stop too coronal

67
Q

a. Why might a tooth restored with MOD amalgam fracture?

b. What could be done to prevent this?

A

a. amalgam not bonded to tooth tissue - unsupported enamel more likely to fracture
buccal cusps can be thin
parafunction
margins on occlusal contacts

b. bond with panavia
porcelain inlay
composite
crown
good preparation
68
Q

Why would a fixed/fixed adhesive bridge debond?

A 
poor prep
poor bonding technique
incorrect occlusal forces
different pathways for torque
caries
69
Q

Why is a single wing of a fixed/fixed bonded bridge debonding a bad thing?

A

difficult to clean underneath, cant move. can get caries developing underneath
patient might not know

70
Q

what are andrews 6 keys?

A
  1. tight contacts, no rotations
  2. class I incisors
  3. class I molars
  4. flat occlusal plane
  5. long axis is slightly mesial
  6. crowns canines back are lingually inclined
71
Q

What are different surgical procedures for orthognathic surgery?

A 
Le fort 1
anterior maxillary osteotomoy
advancement BSSO
set back (VSSO)
genioplasty
72
Q

design a URA for retroclining anterior teeth

A
  • Active: Roberts retractor 0.5mm in tubing
  • Retention: Adams cribs 6/6 0.7mm HSSW
  • ?Anchorage: Stops mesial to 3/3?
  • Baseplate: Flat anterior biteplane

Dentistry BDS4 (20 decks)

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