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BDS4 Orthodontics > Class 2 Division 1 > Flashcards

Class 2 Division 1 Flashcards

1
Q

What is the definition of class 2 division 1

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

How common is class 2 division 1

A

Most common

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3
Q

What are the reasons for tx of class 2 div 1

A
  • There are often concerns regarding the aesthetics
  • There are concerns regarding dental health
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4
Q

What are the concerns regarding dental health

A

o Prominent incisors increases risk of trauma especially if they have incompetent lips as the lower lip is not present to protect them

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5
Q

What is the threshold measurmenet for OJ for it to fall into the high risk category

A

o If the overjet is >9mm then they are twice as likely to suffer trauma and hence fall into the IOTN 5a score

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6
Q

What can the aetiology of class 2 div 1 be divided into

A
  • skeletal pattern
  • soft tissues
  • dental factors
  • habits
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7
Q

What is the most common AP skeletal pattern associated with class 2 div 1

A

Class 2
possible for it to be class 1/3

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8
Q

How can we get a class 2 div 1 on a class 1/3 skeletal base

A

this can occur when the upper incisors are proclined and/or the lower incisors are retroclined either by the soft tissues or a habit or due to a buccally displaced/crowded central incisor

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9
Q

What is the common cause of the class 2 skeletal base

A

Commonly due to a retrognathic mandible but maxillary protrusion is also possible although less common

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10
Q

What is the vertical skeletal pattern associated with class 2 div 1

A

 Found in association with a range of vertical skeletal patterns
 The more significant the underlying skeletal discrepancy in any plane, the more difficult it is to treat

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11
Q

If the FMPA/LAFH is effected, are they likely to be increased or decreased

A

increased

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12
Q

Is there nay association with transvere skeletal pattern + class 2 div 1

A

No particular association with transverse problems

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13
Q

What is SNA

A

relates the maxilla to the anterior cranial base where A is the point at the depth of the concavity of the maxilla

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14
Q

What is SNB

A

relates the mandible position in relation to the anterior cranial base

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15
Q

What is ANB

A

SNA – SNB

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16
Q

What is the normal ANB

A

3 +/- 2 but for a class 2 div 1 we would expect the ANB to be bigger

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17
Q

What is the soft tissue presentation that can contribute to the malocclusion

A

o Lips are often incompetent due to the prominence of the incisors and/or underlying skeletal pattern

o The lower lip trap can be aetiological in the increased overjet

o If the lips are incompetent then special effort is required to create an anterior oral seal and this can be done in different ways, how the anterior oral seal is achieved effects the presentation of the class 2 division 1 incisor relationship

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18
Q

What arethe two ways that a class 2 div 1 w/ incompetent lips can achieve an oral seal

A

Lip to lip seal by activity of circum-oral musculature & mandible postured to allow lips to meet

Or

Lower lip drawn up behind upper incisors and tongue placed forwards between incisors to lower lip

Or

Combo

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19
Q

If lip to lip contact is not possible and the lower lip is drawn up behind the upper incisors, what can this lead to

A

this can retrocline the lower labial segment and/or proclined the upper incisors resulting in an incisor relationship that is more severe than the underlying skeletal pattern

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20
Q

If the tongue comes forawrd to contact the lower lip, what can occur

A

proclination of the lower incisors may occur, helping to compensate for the underlying skeletal pattern. This type of soft tissue behaviour if often associated with increased vertical skeletal proportions and/or grossly incompetent lips or a habit

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21
Q

What are dental factors that can contribute to the class 2 div 1

A
  • crowding (may however have an aligned or spaced arch)
  • overbite
  • molar relationship
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22
Q

How can crowding lead to an OJ

A

Crowding –> due to the shortage of space, the upper incisors may be displaced labially to an overjet

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23
Q

Is overbite increased or reduced

A

Can vary, impacted by the FMPA angle

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24
Q

What is the most common molar relationship

A

Tends to be class 2 but it is possible to have a class 1 If there is space in the lower jaw resulting in mesial drift

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25
Q

What can the chronic open lips (incompetent) lead to

A

Habitually parted lips may lead to drying of the gingiva and exacerbation of any pre-existing gingivitis

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26
Q

What is the term for sucking habits

A

non-nutritive sucking habits

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27
Q

How can habits contribute to class 2 div 1

A

 Proclination of upper anteriors
 Retroclination of lower anteriors
 Localised anterior open bite/incomplete open bite
 Narrow upper arch

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28
Q

How does the sucking habit narrow the arch

A

Mandible is left slightly open leaving the buccinator unopposed which can cause the maxilla to collapse resulting in a narrower upper arch and possibly an upper posterior crossbite

29
Q

What are the tx principles of habit

A
  • reinforcement
  • removable appliance habit breaker
  • fixed appliance habit breaker
30
Q

What is the removable appliance habit breaker

A

Passive URA which prevents thumb being pressed against palate

31
Q

What is the fixed appliance habit breaker

A

Palatal arch with section of wire behind central incisors to prevent thumb from entering mouth

32
Q

Why is age important in breaking habits

A

if the habit persists beyond 9 years old then it will be more disruptive to the occlusion because the eruptive potential of the incisors reduces at this point

33
Q

Once the habit is stopped, when should we treat the malocclusion

A

Once habit is stopped, should allow time for spontaneous improvement and then treat the residual malocclusion if required

34
Q

What are the 5 management options

A
  • accept
  • attempt growth modification
  • simple tipping of teeth
  • camoflauge
  • orthognathic surgery
35
Q

When should we accept the malocclusion

A

If the overjet is mild then this will result in a low IOTN score and therefore tx is not required

If there is a significant overjet but the patient is not unhappy

36
Q

What should the patient be warned about in regards to accepting the malocclusion

A

patient should be advised of the trauma risk and possibility that treatment may be more difficult in the future

37
Q

What are the two ways to attempt growth modification

A
  • headgear
  • functional appliance
38
Q

What is the function of headgear

A

Function is to restrain growth of the maxilla horizontally and/or vertically

Does this by using the back of the head as anchorage support and force is applied to try and distalise the upper molars

Not common anymore due to social acceptability

39
Q

How do functional appliances work

A

Utilizes, eliminates or guides the force of muscle function, tooth eruption and growth to correct a malocclusion

Used mostly for class 2 div 1

40
Q

What is the aim of functional appliance

A

Aim is to produce restraint of maxillary growth and encourage mandibular growth

Theory is it encourages the mandible to grow as it is pulled downwards and forwards, out of the fossa stimulating muscle growth

41
Q

What can then therapeutic effects be categorized into

A

dentoalveolar changes (main change)
skeletal changes (minor degree)

42
Q

What are the dentoalveolar changes that may be done with functional appliance

A

o Distal movement of the upper dentition
o Mesial movement of the lower dentition
o Retroclination of the upper incisors
o Proclination of the lower incisors

43
Q

Why are the skeletal changes by functional appliances debated

A

o Randomised controlled trials indicate that degree of maxillary restraint and mandibular growth is usually small (only 1-2mm)
o Significant variation in response
o It is hard to know whether the growth would have happened anyway without the appliance

44
Q

What are the types of removeable functional appliances

A

tooth borne & soft tissue borne

45
Q

What are the 2 tooth borne functional appliances

A

twin block
activator/bionator

46
Q

What is the twin block

A
  • Most widely used
  • Clasps present on the upper and lower teeth with blocks in between
47
Q

How does the twin block work

A

The blocks hold the mandible forward in a postural position bringing the teeth closer to edge to edge

48
Q

What is the soft tissue born functional appliance

A

Frankel FRII

49
Q

How does frankel FRII work

A
  • Designed to correct class 2
  • Sits into soft tissue sulcus with shields and aims to posture the mandible and expand the maxilla and effect the way the alveolar processes grow
50
Q

When should functional appliances be used

A
  • Should be used during pubertal growth spurt (ideally)
51
Q

What are the two types of use of functional appliance

What age

A

early and later u se

52
Q

When is early use done

A

10 YO
2 phase tx

53
Q

Why is early use of functional appliance done

A

This is to remove the risk of trauma and risk of bullying and then second phase would be with fixed appliances once the permanent dentition is complete

54
Q

What is the disadvantages of early use

A

Early skeletal effects from functional appliance/headgear therapy not maintained long term

Overall treatment time increased due to 2 phase treatment
* Early functional appliance + retention
* Fixed appliance in early permanent dentition

Research doesn’t show much difference between those treated early and those who waited until the permanent dentition

55
Q

What are the advantages of early use

A

Improve appearance earlier
Reduced risk of trauma
Often better compliance with appliance wear

56
Q

What is later use of functional appliance

A

Start with functional then move onto fixed straight away

57
Q

What do we use for simpling tipping of teeth

A

URA

58
Q

Is it common to simply tip the teeth

A

No
not common tx

59
Q

When may a URA be prescribed for class 2 div 1

A

 Very mild class 2/1
 Overjet due to proclined and spaced incisors
 Overbite is favourable
 Only then after a specialist assessment has been done and treatment recommended would this be used

60
Q

Write the lab prescription for the URA for class 2 div 1

A

 Active component: Robert retractor in 0.5mm tubing
 Retention: Adams crib 6/6 0.7mm HSSW
 Stops mesial to 3/3
 Baseplate: flat anterior biteplane

61
Q

What is camouflage

A

No growth modification, skeletal relationship remains the same but fixed appliance used to move the teeth

62
Q

How do we camouflage class 2 div 1

A

reduce OJ

63
Q

How can we reduce the overjet in camouflage

A

Take out premolars to make space and then take upper canines back and the incisors
Can also extraction 7s and do distal movement of the upper 6s
Proclining lower incisors

64
Q

What must a px be warned about when proclining lower incisors

A

risk of gingival recession as limited alveolar bone to maintain coverage

65
Q

When is orthognathic surgery carried out

A

when growth is complete

66
Q

What is the indication for orthognathic surgery

A

when skeletal discrepancy is severe in A/P and/or vertical direction

67
Q

What jaws will be moved in orthognathic surgery for class 2 div 1

A

Usually involves mandibular surgery, but may also involve maxillary surgery
Usually mandibular advanced however sometimes maxilla and mandible moved forward together

68
Q

When do we use fixed appliance with orthognathic surgery

A

Before surgery to align and coordinate dental arches
During surgery
After surgery

BDS4 Orthodontics (10 decks)

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