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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
how does headgear and EO traction work
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
why do you need extremely good pt cooperation for headgear?
wear at least 14 hours per day
27
how does a functional appliance work?
"utilise, eliminate or guide the forces of muscle function, tooth eruption and growth to correct a malocclusion"
28
what malocclusion is functional appliances mostly used for?
class 2 div 1
29
what other malocclusions can fct appliances be used for?
``` class 2 div 2 class 3 (but limited use) ```
30
describe the effect of fct appliances
mandible postured down and forwards activates masticatory muscles. Stretches masseter - apply distalising force to maxilla, apply mesialising force to mandible
31
how should the registration for a functional appliance be taken?
with the teeth as close to edge to edge as possible
32
2 main types of fct appliance
removable or fixed
33
removable fct appliance
``` 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
fixed functional appliance
Herbst - capping bonded onto surface of teeth, connecting rod between upper and lower which postures mandible forward
35
twin block
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
therapeutic effect of twin block
aim to produce restraint of maxillary growth and encourage mandibular growth
37
what is the success of a twin block dependent on?
favourable growth and enthusiastic patient
38
what are the actual effects of a twin block?
``` 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
why should a fct appliance be used during growth?
teeth move more easily more compliant can harness effect of favourable growth if they have it
40
two options for timing of a fct appliance
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
disadvantages of early fct appliance tx
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
advantages of early fct appliance tx
improve appearance earlier (teasing and potential psychological benefit) reduce risk of trauma often better compliance with appliance wear
43
when are the only times URAs would really be used?
v mild class 2 or class 1 OJ due to proclined and spaced incisors OB favourable and then only after a specialist assessment
44
URA to retrocline anterior teeth
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
when is camouflage useful?
if haven't worn fct well enough/are too old for a fct
46
what does camouflage usually involve?
fixed appliances | if goal is to reduce the OJ may need U arch extractions to give space (or distal movement)
47
txing an increased OJ and class 2 molars - camouflage
``` 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
when would orthognathic surgery be indicated?
growth complete and profile concerns - F 18-19 yrs - M 20-21 yrs severe skeletal discrepancy in AP and/or vertical direction
49
what does orthognathic surgery usually involve?
mandibular surgery but may also involve maxillary surgery - maxillary impaction - mandibular advancement e.g. bilateral sagittal split osteotomy
50
what appliance is usually required as well as orthognathic surgery?
fixed - before and after | rectangular SS arch wires with printable hooks - run elastics to fine tune occlusion and keep teeth in correct place
51
class 2 elastic
correct a class 2 occlusion
52
class 3 elastic
correct a class 3 occlusion

Ortho (21 decks)

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