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BDS4 Ortho > Class II Div 1 > Flashcards

Class II Div 1 Flashcards

1
Q

What is the BSI definition of Class II div 1 incisor relationship?

A
  • Lower incisor edges lie posterior to the cingulum plateau of the upper incisors
  • There is an increased overjet
  • Upper central incisors are proclined or of average inclination
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2
Q

What is the percentage of Class II div 1 malocclusions?

A
  • 15-20%
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3
Q

Why are we so concerned about treating Class II div 1 cases?

A
  • Concerns about aesthetics
  • Concerns about dental health
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4
Q

What are the dental health concerns of class II div1 malocclusion?

A
  • Prominent incisors at risk of trauma esp if incompetent lips
  • OJ >9mm twice as likely to suffer trauma
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5
Q

What is the IOTN of OJ >9mm?

A
  • 5a
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6
Q

What A/P skeletal pattern is Class ii div 1 associated with and what type of mandible is this due to?

A
  • Usually Class II skeletal pattern
  • Commonly due to retrognathic mandible (can be maxillary protrusion but less common)
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7
Q

In class ii div1 cases what is the Overjet likely to be due to?

A
  • Skeletal pattern
  • Tooth inclination
  • Combo of both
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8
Q

Does class ii div 1 cases have an association wirh vertical skeletal pattern?

A
  • Found in association with a range of vertical skeletal patterns
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9
Q

Does class ii div 1 cases have an association with transverse skeletal pattern?

A
  • No association
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10
Q

On a lateral ceph what is the normal SNA value? What does this denote?

A

81 +/- 3
- Relationship of Sella, Nasion and A point
- Shows AP position of maxilla relative to cranial base
- Increased shows protrusion
- Decreased shows retrusion

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11
Q

On a lateral ceph what is the normal SNB value? What does this denote?

A

78 +/- 3
- Relationship of Sella, Nasion and B point
- Shows AP position of mandible relative to cranial base

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12
Q

On a lateral ceph what is the normal ANB value an what does tis represent?

A

3 +/- 2
= SNA - SNB
- If ANB angle is reduced pt has Class III skeletal base
- If ANB angle is increased pt has Class II skeletal base

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12
Q

What is the normal MxP/MnP value and what does this represent?

A

27 +/- 4
- Maxillo-mandibular plane angle

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13
Q

What is the normal Ul/MxP value and what does it represent?

A

109 +/- 6
- Upper incisors relative to the maxillary plane
- If increased then upper incisors are proclined
- If decreased upper incisors retroclined

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14
Q

What is the normal Ll/MnP value and what does this represent?

A
  • 93 +/- 6
  • Lower incisors relative to the mandibular plane
  • If increased incisors are proclined
  • If decreased incisors are retroclined
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15
Q

What are the normal LAFH/TAFH values?

A
  • 55%
  • State whether it is increased or decreased or average
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16
Q

Why are lips incompetent?

A
  • Due to prominence of incisors
  • and/or underlying skeletal pattern
17
Q

What is the purpose of trying to correct lip incompetence?

A
  • Achieve an anterior oral seal
18
Q

What are the txt options to achieve an anterior oral seal?

A

1 - Lip to lip seal by activity of circum-oral musculature
- Mandible postured to allow lips to meet

2 - Lower lip drawn up behind upper incisors
- Tongue placed forwards between incisors to lower lip

3 - Combo of these two options

19
Q

What are the dental factors of Class ii div 1 malocclusion that we need to be aware of?

A
  • Increased overjet (incisors proclined or average)
  • Overbite variation
  • See goof alignment, crowding or spacing
  • Molar relationship
  • Habitually parted lips may lead to drying of gingiva and exacerbation of any pre-existing gingivitis
20
Q

What sucking habits can lead to class ii div 1 malocclusion?

A
  • Thumb
  • Fingers
  • Blanket
  • Lip
  • Combination
21
Q

What are the occlusal features of sucking habit?

A
  • Proclination of upper anteriors
  • Retroclination of lower anteriors
  • Localised AOB or incomplete OB
  • Narrow upper arch (may see unilateral posterior crossbite)
22
Q

What are the habit txt principles (3 of them)?

A

Stop habit
– Reinforcement
– Removable appliance habit breaker
– Fixed appliance habit breaker
* Allow spontaneous improvement
* Treat residual malocclusion if required

23
Q

What are the 5 management options for Class ii div1 maloclusions?

A
  1. Accept
  2. Attempt growth modification
  3. Simple tipping of teeth
  4. Orthodontic Camouflage
  5. Orthognathic surgery
24
Q

When we choose to accept a class ii div 1 malocclusion what dentally are we accepting?

A
  • Mildy increased OJ
  • Sig OJ but pt not unhappy
  • Be careful as txt options may be more difficult in the future
  • Give advice regarding a mouthgaurd due to increased chance of trauma
25
Q

What is a functional appliance?

A

“Functional appliances utilize, eliminate, or
guide the forces of muscle function, tooth
eruption and growth to correct a
malocclusion

  • Used mostly for class ii div 1 cases
26
Q

What are the two options we have when attempting growth modification?

A
  • Headgear where try and restrain growth of maxilla horizontally and/or vertically
  • Functional appliance
27
Q

What are some types of removable functional appliance?

A
  • Tooth borne (Twin block or Activator/bionator)
  • Soft tissue born (Frankel FR II)
28
Q

What type of fixed functional appliance do we have?

A
  • Herbst fixed functional appliance
29
Q

What are the aims of functional appliances?

A
  • Produce restraint of maxillary growth and encourage mandibular growth
  • Success depend on favorable growth (useful during growth spurt) and enthusiastic pt
30
Q

What is the therapeutic effect of functional appliances on dento-alveolar and skeletal?

A
  • Mostly dento-alveolar changes
  • Minor degree of skeletal changes
31
Q

What is the dento-alveolar change that occur during functional appliance therapy?

A
  • Distal movement upper dentition
  • Mesial movement lower dentition
  • Retroclination of upper incisors
  • Proclination of lower incisors
32
Q

What is the little skeletal change observed in functional appliance therapy?

A
  • RCT’s indicate that degree of
    maxillary restraint and mandibular
    growth is usually small (1-2mm)
  • Significant variation in response
33
Q

What are your options for when to use a functional appliance?

A
  • During growth and if poss during pubertal growth spurt

1 - Early use about yrs old with a 2 phase txt
2 - Later use in late mixed or early permanent dentition with a 1 phase txt

34
Q

What are the possible disadvantages of early txt with functional appliance therapy?

A
  • Early skeletal effects from functional appliance or headgear therapy not maintained long term
  • 2 phase txt so txt time increased
  • Research shows little difference in results for early txt and those who waited until permanent dentition
35
Q

What are the potential benefits of early txt for functional appliances>

A
  • Improve appearance earlier (teasing & potential
    psychological benefit)
    – Reduce risk of trauma
    – Often better compliance with appliance wear
36
Q

What is the URA appliance 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

37
Q

What is an option for adult dentition with increased OJ and class II molars?

A
  • Camouflaged by fixed appliances
  • XLA premolar upper arch to create space for OJ reduction
  • Creates class III molar relationship but reduces OJ and looks better

2 - Non XLA OJ reduction which allows for molar correction , distal movement of U6s aided by XLA of U7s

38
Q

When is orthognathic surgery considered?

A
  • When growth is complete
  • Skeletal discrepancy is severe in A/P and / or vertical direction
39
Q

What does orthognathic surgery involve?

A
  • Mandibular surgery but may also involved maxillary
  • Fixed appliances before / during / after surgery
40
Q
A

BDS4 Ortho (9 decks)

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