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Ortho > Class II div II > Flashcards

Class II div II Flashcards

1
Q

What is the incidence of class 2 div 2 malocclusions?

A

10-18%

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2
Q

Common extra oral features of class 2 div 2 patients?

A
  • Short, broad face due to decreased LFH
  • Convex shape face
  • Prominent chin (labiomental fold)
  • High upper lip line
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3
Q

Common intra oral features in class 2 div 2

A

MOLAR - Usually class 2 molar (medial drift of 6)
OB - Deep overbite - can be incomplete or traumatic
- Increased interincisal angle
OJ - Upper incisors normal or retroclined
- Lower incisors normal or retroclined
- Upper laterals may be tipped labially

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4
Q

Describe the AP skeletal pattern in class 2 div 2 patients? (aetiology)

A
  • usually MILD class II
  • Can be moderate-severe class II (rare)
  • Class I or III
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5
Q

Why is class 2 div 2 associated with mild class 2 AP skeletal base and not moderate-severe?

A
  • Moderate-severe class 2 patterns is more likely to result in class 2 div 1 because the upper incisors will lie out of control of the the lip
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6
Q

Describe the vertical skeletal relationship in class 2 div 2? what type of growth?

A
  • LFH usually reduced

associated with forwards and upwards mandibular growth

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7
Q

What type of growth is unfavourable in class 2 div 2 patients?

A

Forwards and upwards growth as this deepens the bite as growth proceeds (unless an occlusal stop is created)

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8
Q

Describe the transverse skeletal relationship in class 2 div 2

A
  • Lingual XB of upper 4s due to wide maxilla and narrow lower interincisal angle
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9
Q

Describe how the deep overbite develops in class 2 div 2 patients

A
  • Lack of occlusal stop for the lower incisors results in continued development of the LLS (increases OB)
  • Unfavourable growth which deepens the bite
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10
Q

Dental aetiological factors associated with class 2 div 2 and why

A

Crowding can be exacerbated by retroclination (smaller spaced occupied = crowding)
Lack of occlusal stop (reduced or absent cingulum plateau of upper incisors)

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11
Q

How may the upper laterals be rotated in class 2/2?

A

Rotated mesiolabially out of the arch

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12
Q

Describe the arch forms in class 2 div 2

A

Upper arch - broad and square

LA - narrow or V shaped

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13
Q

Describe the soft tissue factors in class 2 div 2

A
  • Lower lip line is usually higher relative to the upper incisors - covers more than 1/3rd of the upper incisors (causes retroclination)
  • Or bimaxillary retroclination due to strap lips
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14
Q

Why may lateral incisors remain in the normal position whilst central incisors retrocline in class 2/2?

A

Lateral incisors have a shorter crown therefore they may be unaffected by the action of the lip

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15
Q

List the treatment options for class 2 div 2 patients

A
  • Nothing
  • Functional appliance
  • Fixed appliances
  • Surgery
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16
Q

When would class 2 div 2 be accepted / no treatment?

A
  • Aesthetics acceptable
  • OB only slightly increased
  • Limited crowing
  • No traumatic overbite
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17
Q

List the ways you can reduce the inter-incisal angles?

A
  • Fixed appliance - torque incisor roots and procline ULS and LLS
  • Functional appliance after proclination of ULS
  • Surgery
18
Q

List the mechanisms to reduce the overbite?

A
  • Intrusion of incisors
  • Eruption of molars
  • Extrusion of molars
  • Proclination of lower incisors
  • Surgery
  • Restorative therapy
19
Q

Explain the effects of incisor intrusion in reduction of overbite in class 2 div 2

A
  • Effects are achieved via relative intrusion

- Molars extrude and vertical growth around the incisors

20
Q

How can anchorage be increased when intruding incisors in class 2/2? why would you need to do this?

A
  • Use of 2nd or 3rd molars

- Aids intrusion of incisors and limits extrusion of the molars

21
Q

How do you achieve eruption of molars for tx of class 2/2 treatment

A
  • URA with anterior bite plane to free occlusion of buccal segment to allow molar eruption
22
Q

How does proclination of the lower incisors reduce overbite in class 2/2

A

Advancement of LLS to reduce overbite as incisors tip labially

23
Q

Why is proclination of lower incisors for tx of class 2/2 less desirable than other options

A

Results in a high risk of relapse post op

24
Q

When should extractions be indicated in class 2/2 tx?

A
  • Moderate-severe crowding

- When space cannot be made by other mechanisms

25
Q

Why should class 2/2 be treated on a non-extraction basis ideally?

A

Lower arch extractions may retrocline LLS further (deepens OB)
- It is also difficult to achieve space closure if there is a low MMA

26
Q

What is the ideal appliance for tx of class 2/2

A

Fixed because torque is required to bring about correction of the IIA and to proline LLS

27
Q

What is the limitation of torque movement in class 2/2 tx

A
  • Depends on presence of sufficient cortical bone lingually and palatally
  • Places a strain on anchorage
  • More likely to cause root resorption
28
Q

Indications for functional appliances in class 2/2

A
  • Patients in pubertal growth spurt
  • Mild-moderate skeletal class 2
  • Well aligned lower arch
29
Q

Phases in functional appliance tx for class 2/2

A
  • Pre-functional - URA to procline ULS (reduce IIA)
  • 1st phase = functional
  • 2nd phase = fixed
30
Q

When is ortho camouflage indicated in tx of class 2/2?

A
  • Mild ANB angle

- Mild vertical skeletal discrepancies (OB not grossly increased)

31
Q

Indications for surgery for class 2/2

A
  • Moderate-severe skeletal class II pattern
  • ANB >8
  • Non-growing pt and permanent dentition
  • Unfavourable growth pattern
  • Traumatic bite
32
Q

Stability of class 2/2 post op depends on…?

A
  • Modification of soft tissue environment
  • Growth pattern (favourable)
  • Ideal IIA to produce an occlusal stop
  • Overbite has been reduced with a positive edge centroid position
33
Q

What is a positive edge centroid position (class 2/2?)

A

Lower incisor edge lies 0-2 mm anterior to the midpoint of the root axis of upper incisors

34
Q

How does strap lip contribute to class 2/2 malocclusion?

A

Causes bimaxillary retroclination resulting in class 2/2 malocclusion on any underlying skeletal base

35
Q

Why is extraction of 5s better in class 2/2?

A

Prevents lingual movement of lower incisors during space closure

36
Q

What direction do you torque upper and lower incisors for IIA correction in class 2 div 2

A

Lingual for lower

Palatal for upper

37
Q

How to achieve eruption of molars for lass 2 div 2 tx

A

URA with anterior bite plane

Functional appliance with incisor capping

38
Q

How to achieve extrusion of molars in class 2 div 2 treatment

A

Cervical pull headgear to upper molars

Intermaxillary elastics with FA

39
Q

How does surgery correct OB in class 2 div 2

A

Advances mandible

Achieves lower labial segment set down

40
Q

Explain restorative management in OB reduction for class 2 div 2

A

Increase posterior OVD

Use of dahl appliance to intrude lower incisors or erupt lower molars, with palatal restorations on the upper incisors

Ortho (20 decks)

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