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Ortho > class 2 div 1 malocclusion > Flashcards

class 2 div 1 malocclusion Flashcards

1
Q

definition

A

lower incisor edges lie posterior to the cingulum plateau of the upper incisors
increased OJ
U central incisors proclined or of average inclination

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2
Q

incidence

A

15-20% (most common malocclusion)

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3
Q

why treat?

A

aesthetics
dental health
- prominent incisors at risk of trauma esp if incompetent lips
- OJ >9mm x2 as likely to suffer trauma - IOTN 5a

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4
Q

broad categories of aetiology/features

A

skeletal pattern
STs
dental factors
habits

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5
Q

AP skeletal pattern

A

usually associated with a class 2 skeletal pattern
commonly due to a retrognathic mandible
- maxillary protrusion less common
do see with skeletal class 1
v rarely see with skeletal class 3 but possible - could be purely due to STs e.g. lip trap

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6
Q

skeletal pattern - vertical

A

found in association with a range of vertical skeletal patterns
decreased vertical = increased OB
increased vertical = decreased OB/AOB

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7
Q

skeletal pattern - transverse

A

no particular association with transverse problems

could have buccal segment CB due to maxillary contraction

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8
Q

incompetent lips

A

don’t sit together at rest without muscular activity

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9
Q

what are incompetent lips often due to?

A

prominence of incisors and/or underlying skeletal pattern

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10
Q

what ST factor can be an etiological factor in increased OJ?

A

L lip trap

  • proclination Us
  • retroclination Ls
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11
Q

what is the consequence of incompetent lips when swallowing?

A

special effort is needed to achieve an anterior oral seal

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12
Q

achieving an anterior oral seal

A

1 - lip to lip seal by activity of circum-oral musculature - mandible postured to allow lips to meet
2 - L lip drawn up behind U incisors, tongue placed forwards between incisors to L lip - tends to make OJ worse
3 - combination of these

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13
Q

dental factors

A

increased OJ (incisors proclined or average?)
OB varies
can see good alignment, crowding or spacing
- common to have spaced U anteriors if proclined
molars usually class 2 but crowding could alter this
habitually parted lips

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14
Q

consequences of habitually parted lips

A

drying of gingiva and exacerbation of any pre-existing gingivitis
rolled gingival margins
U lip not covering U gingival margin

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15
Q

non-nutritive sucking habits

A 
thumb
fingers
blanket
lip
combination
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16
Q

what does the effects of a sucking habit depend on?

A

duration and intensity

- if >6hrs per day will have occlusal effects

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17
Q

occlusal features of a sucking habit

A

proclination of U incisors
retroclination of L incisors
localised AOB or incomplete OB
narrow upper arch (may see unilateral posterior CB)

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18
Q

why does a sucking habit result in a narrow upper arch?

A

tongue in low position due to thumb

maxilla constricts due to action of buccinator

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19
Q

habit treatment principles

A

stop before age 9
allow spontaneous improvement - <9yrs would hope for improvement
tx residual malocclusion if required

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20
Q

methods of stopping sucking habit

A

reinforcement
removable appliance habit breaker (good for pt who wants to help themselves)
fixed appliance habit breaker (palatal arch with goalposts at front - stops thumb going into mouth)

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21
Q

management options

A 
accept
attempt growth modification
simple tipping of teeth (URA)
camouflage
orthognathic surgery
22
Q

indications to accept

A

mildly increased OJ

significant OJ but not unhappy and not keen on tx

23
Q

discussion to have with pt/parent re accept

A

will any tx options be more difficult in future?

advice re mouthguard for contact sports

24
Q

what is growth modification and when can it be done?

A

you apply significant force to the skeletal bases to try and improve the underlying skeletal discrepancy
while still growing (8-14yrs)

25
Q

how does headgear and EO traction work

A

try and restrain growth of the maxilla horizontally and/or vertically
spring loaded and facebow (500g force)
- move U molars distally and decrease vertical dimension

26
Q

why do you need extremely good pt cooperation for headgear?

A

wear at least 14 hours per day

27
Q

how does a functional appliance work?

A

“utilise, eliminate or guide the forces of muscle function, tooth eruption and growth to correct a malocclusion”

28
Q

what malocclusion is functional appliances mostly used for?

A

class 2 div 1

29
Q

what other malocclusions can fct appliances be used for?

A 
class 2 div 2
class 3 (but limited use)
30
Q

describe the effect of fct appliances

A

mandible postured down and forwards
activates masticatory muscles. Stretches masseter - apply distalising force to maxilla, apply mesialising force to mandible

31
Q

how should the registration for a functional appliance be taken?

A

with the teeth as close to edge to edge as possible

32
Q

2 main types of fct appliance

A

removable or fixed

33
Q

removable fct appliance

A 
tooth-borne
 - twin block (most common)
 - activator/bionator
soft-tissue borne
 - Frankel2 - buccal shields and wire frame which fits around teeth without clasping onto teeth
34
Q

fixed functional appliance

A

Herbst - capping bonded onto surface of teeth, connecting rod between upper and lower which postures mandible forward

35
Q

twin block

A

midline screw to allow expansion - usually needed to keep pace with lower arch
labial bow - if proclination and spacing
speech often an issue - persistence
get lat open bite - resolves in a few months e.g. just wear block at night

36
Q

therapeutic effect of twin block

A

aim to produce restraint of maxillary growth and encourage mandibular growth

37
Q

what is the success of a twin block dependent on?

A

favourable growth and enthusiastic patient

38
Q

what are the actual effects of a twin block?

A 
mostly dento-alveolar changes
 - distal movement U dentition
 - mesial movement L dentition
 - retroclination of U incisors
 - proclination of L incisors
minor degree of skeletal changes 
 - significant variation in response

skeletal 27%, dental 73%

39
Q

why should a fct appliance be used during growth?

A

teeth move more easily
more compliant
can harness effect of favourable growth if they have it

40
Q

two options for timing of a fct appliance

A

early use about 10years old (2 phase tx) (8yrs earliest)

  • have to withdraw tx for transition from mixed to permanent (2yrs)
  • then use fixed

later use - late mixed or early permanent dentition (1 phase tx)

41
Q

disadvantages of early fct appliance tx

A

early skeletal effects from fct appliance or headgear therapy not maintained in long term
overall tx time increased, 2 phase tx
- early fct appliance plus retention
- fixed app in early permanent dentition
research shows little if any difference in results between those treated early and those who waited until permanent dentition

42
Q

advantages of early fct appliance tx

A

improve appearance earlier (teasing and potential psychological benefit)
reduce risk of trauma
often better compliance with appliance wear

43
Q

when are the only times URAs would really be used?

A

v mild class 2 or class 1
OJ due to proclined and spaced incisors
OB favourable
and then only after a specialist assessment

44
Q

URA to retrocline anterior teeth

A

active component - Roberts retractor, 0.5mm HSSW in tubing
retention - Adams clasps 0.7mm HSSW
anchorage - stops mesial to 3s (have already been retracted)
baseplate - FABP

45
Q

when is camouflage useful?

A

if haven’t worn fct well enough/are too old for a fct

46
Q

what does camouflage usually involve?

A

fixed appliances

if goal is to reduce the OJ may need U arch extractions to give space (or distal movement)

47
Q

txing an increased OJ and class 2 molars - camouflage

A 
ext method - ext 4s, bring molars forward, move anteriors back
non-ext method - distalise molars to class 1 (aided by ext of U7s - but would want 8 in good position to come down and replace 7 when tx completed)
48
Q

when would orthognathic surgery be indicated?

A

growth complete and profile concerns
- F 18-19 yrs
- M 20-21 yrs
severe skeletal discrepancy in AP and/or vertical direction

49
Q

what does orthognathic surgery usually involve?

A

mandibular surgery but may also involve maxillary surgery

  • maxillary impaction
  • mandibular advancement e.g. bilateral sagittal split osteotomy
50
Q

what appliance is usually required as well as orthognathic surgery?

A

fixed - before and after

rectangular SS arch wires with printable hooks - run elastics to fine tune occlusion and keep teeth in correct place

51
Q

class 2 elastic

A

correct a class 2 occlusion

52
Q

class 3 elastic

A

correct a class 3 occlusion

Ortho (21 decks)

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