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Dentistry BDS4 > Orthodontics > Flashcards

Orthodontics Flashcards

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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
management of increased OJ
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
26
Causes of increased OB
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
27
how to treat increased OB
FABP to allow molars to erupt | procline lower incisors
28
Cause of AOB
vertical growth > horizontal growth | habits, tongue thrust, iatrogenic, CLP
29
Treatment of AOB
cease habit, FPBP
30
Treatment of reverse OJ
1. Do nothing and accept 2. camouflage 3. surgery if ANB below -4 lower incisal angle to mand plan <80
31
How do you treat XB?
AXB - z spring and FPBP to disclude teeth | PXB - quad helix, RME, midline palatal screw and FPBP
32
what are indications for removable appliances?
``` 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
What are the active components of removable appliances and what are they made out of
Z springs - 0.5mm HSSW buccal canine retractor roberts retractor midline palatal screw
34
What are the retentive components of removable appliances and what are they made out of?
Adams cribs - 0.7mm HSSW (0.6mm on deciduous) southend clasp labial bow
35
What are the components of fixed orthodontic appliances?
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
What is the mode of action of functional appliances? and give an example of one
25% skeletal change, 75% dental tooth tipping | twin block appliance
37
What information would you give a patient who has jsut been given their removable appliance?
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
How does a twin block appliance work?
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
What is dento-alveolar compensation?
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
What is a supernumerary tooth?
a tooth that is in addition to the regular dentition
41
What are TADs and why are they used?
``` temporary anchorage devices - mini implants to provide anchorage for ortho treatment no osseointegration easily placed absolute anchorage removable patient compliance unnecessary ```
42
Who is involved in treating a patient with class III malocclusion
``` psychology ortho surgical technologist restorative speech and language therapy oral hygeine ```
43
list the steps involved in class III malocclusion treatment
``` tooth alignment, eliminating crowding/spaces and XB coordination of the arches decompensate incisors flatten occlusal plane surgical fixatoin port surgery ortho ```
44
What different orthognathic surgeries are carried out?
Le fort 1 osteotomy ant max osteotomy BSSO genioplasty
45
What are the risk/benefits you need to discuss with a patient who has carious 6s but wants ortho Tx?
- 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
What are some risks of orthodontic treatment?
- root resorption - relapse - failure to complete treatment - treatment failure - devitalising of tooth - pain - trauma from components - decalcification of tooth
47
when would you treat an anterior open bite?
if mand displacement on closing if traumatic aesthetics
48
What characteristics of a malocclusion would make it ideal for treatment with a URA
- palatally tipped teeth - 1 or 2 teeth needing movement - class 1 molar relationship - space
49
What are causes of ectopic canines?
- ectopic crypt position - absent laterals - crowding - retention of deciduous canine - genetics
50
How do you monitor the eruption of canines?
palpation from 9/10 look at inclination of 2s mobility of cs colour of cs
51
What are the signs of impacted canines?
- delayed eruption - retained Cs - unable to palpate - distal tipping of 2s loss of vitality or mobility of 1s/2s
52
What are functions of a URA other than tipping teeth?
- space maintainer - habit breaker - retainer - correct OB
53
What warnings do you give someone on provision of a URA?
- big and bulky - non compliance increases duration - will feel uncomfortable, saliva, speech - will settle - beware of hot drinks
54
Waht instructions do you provide to somone when you have them a URA?
- wear 24hs - remove for contact sport or swimming - clean after eating with soft brush and water - dont eat hard or sticky foods
55
What do you use in a URA to correct an ACB and a PCB?
ACB - Z spring | PCB - midline palatal screw
56
What are the signs of a digit sucking habit?
``` narrow and high palate PCB AOB ACB increased OJ proclined uppers/retroclined lowers ```
57
What are risks of bonded and pressure formed retainers?
bonded: can debond, caries, gingivitis, poor OH, fracture of wire pressure: lost/chewed by dog compliance and no longer fitting, keeping clean
58
How would you assess vertical skeletal relationship?
LAFH vs TFH - should be 50% ish | FMPA - should meet at the back of the head
59
What special investigations would you do for a patient before referring them on to ortho?
study models and bite recording | lateral ceph -
60
What are some causes of AOB?
digit sucking tongue thrust fracture of mandible skeletal discrepancy
61
How would you monitor canine movement?
measure, can use a definite point to compare against
62
what are different types of orthodontic retention?
hawley retainer vacuum formed retainer fixed bonded retainer
63
A patient with fixed ortho presents with white areas around the brackets, what could be the cause?
- demineralisation - excess cements - plaque
64
How does a URA affect the anterio-posterior skeletal relationship?
it doesnt
65
How does a URA affect the vertical skeletal relationship?
FABP would decrease overbite and increased LAFH
66
What would cause the failure of removal of infected material during RCT?
inadequate apical shaping indadequate coronal flare inadequate irrigation apical stop too coronal
67
a. Why might a tooth restored with MOD amalgam fracture? | b. What could be done to prevent this?
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
Why would a fixed/fixed adhesive bridge debond?
``` poor prep poor bonding technique incorrect occlusal forces different pathways for torque caries ```
69
Why is a single wing of a fixed/fixed bonded bridge debonding a bad thing?
difficult to clean underneath, cant move. can get caries developing underneath patient might not know
70
what are andrews 6 keys?
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
What are different surgical procedures for orthognathic surgery?
``` Le fort 1 anterior maxillary osteotomoy advancement BSSO set back (VSSO) genioplasty ```
72
design a URA for retroclining anterior teeth
* 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

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