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BDS4 Orthodontics > Class 2 Division 1 Malocclusions > Flashcards

Class 2 Division 1 Malocclusions Flashcards

1
Q

What is the BSI definition of a Class 2 Div 1 Malocclusion

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 prevalent are different malocclusion forms?

A

Class I 67-72%

Class II div 1 15-20%

Class II div 2 10%

Class III 3%

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3
Q

What are the reasons for treating class 2 div 1?

A
  1. Concerns re aesthetics
  2. Concerns re dental health
    –> Prominent incisors at risk from trauma especially if incompetent lips
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4
Q

Why does a >9mm OJ score an IOTN of 5a?

A

Due to risk of trauma
-> twice as likely

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5
Q

What factors are involved in the aetiology of class 2 div 1 patients?

A

Skeletal pattern
– A/P, Vertical, Transverse

Soft tissues

Dental factors

Habits

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6
Q

What are the features of the AP skeletal pattern in class 2 div 1?

A

Usually associated with a class 2 skeletal relationship
-> Commonly due to a retrognathic mandible (maxillary protrusion less common)

*Seen in class 1 if proclined incisors, can be seen in class 3 too

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7
Q

What causes the OJ in class 2 div 1 patients?

A

Tooth inclination- proclination of uppers/retroclination of lowers

Skeletal pattern

Combination of both

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8
Q

What are the features of Vertical and Transverse relationships in class 2 div 1 patients?

A

Vertical- can be associated with high or low angle
-> often there is an increased FMPA

Transverse- no particular association with transverse issues (maxilla may be narrower)

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9
Q

What are the normal cephalometric values in a class 1 patient?

A

SNA = 81 +/- 3
SNB = 78 +/- 3
ANB = 3 +/- 2
MxP/MnP = 27 +/- 4
UI/MxP = 109 +/- 6
LI/MnP = 93 +/- 6
LAFH:TAFH- 55%

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10
Q

Why are maxillary and Frankfort plane often used interchangeably?

A

Often parallel in most patients

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11
Q

In which ways can soft tissues contribute to OJ in class 2 div 1 patients?

A

Lip traps can cause proclination of upper anteriors

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12
Q

What are the ways in which a patient with incompetent lips can create 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
– Tongue placed forwards
between incisors to lower
lip

–> Combination of these

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13
Q

What are the dental features of a class 2 div 1 malocclusion?

A

Increased overjet

Varied OB

Molar relationship- usually class 2

Can have good alignment, crowding or spacing

May have hyper plastic gingivitis due to parting of the lips causing drying

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14
Q

Why may crowding contribute to class 2 div 1 malocclusions?

A

Laterals can be tucked in behind centrals causing them to procline more

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15
Q

Which sucking habits (Non-necrotive) may lead to class 2 div 1 maolocclusion?

A

Thumb
Fingers
Blanket
Lip
-> Combination

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16
Q

What are the occlusal features of a sucking habit?

A

Proclination of upper anteriors

Retroclination of lower anteriors

Localised AOB or incomplete OB

Narrow upper arch (may see unilateral posterior crossbite)

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17
Q

Why may a patient with a sucking habit have an asymmetrical AOB?

A

They only suck one thumb

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18
Q

What can be used to stop a sucking habit?

A

Wearing a glove
Putting something on thumb
Positive Reinforcement
Removable appliance habit breaker
Fixed appliance habit breaker (with goal post)

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19
Q

What can occur if a patient stops habit quickly

A

Spontaneous improvement

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20
Q

What are the issues with using habit breakers in patients beyond 9 years old?

A

Disruption to occlusion as root formation could be reduced

21
Q

What are the different management options for a class 2 div 1 maolocclusion?

A
  1. Accept
  2. Attempt growth modification
  3. Simple tipping of teeth URA
  4. Camouflage
  5. Orthognathic surgery
22
Q

In what cases may accepting a class 2 div 1 be considered?

A

If patient does not want treatment

Mildly increased OJ

Low IOTN

Minimal aesthetic concern

23
Q

What should you warn a patient about their untreated class 2 div 1 malocclusion in the future?

A

Future treatment will be more difficult

Trauma risk is higher

24
Q

What can be used to attempt growth modification in class 2 div 1 cases?

A

Head gear (uncommon)

Functional appliances

25
Q

How does head gear work

A

 Head gear- restrains maxillary growth (unsure about evidence for effect long term)
 Back of head is used as anchorage support- force is applied to distalise upper molars and intrude them (good for AOB/reduced OB)
 14 plus hours per day required

26
Q

What is the purpose of functional appliances?

A

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

-> used mostly in class 2 div 1 cases (sometimes div 2)

27
Q

How do Functional appliances work?

A

 Postures mandible forwards and uses masticatory muscles to pull back upper teeth with it
 Condyles grow more as they move out of the glenoid fossa

-> aims to restrain maxillary growth and promote mandibular growth

28
Q

What are the types of functional appliances that can be used for class 2 div 1?

A

 Removable- twin block (most widely used)- clasps onto teeth and holds teeth in edge-to-edge position

 Activator/bionator- less commonly used

 Frankel 2 (soft tissue borne)- postures mandible and allows expansion of the maxilla

 Fixed (Herbst)- pistons and connecting rods (more reliable but prone to breakage)

29
Q

What is the main issue with removable orthodontic appliances?

A

Compliance issues

30
Q

What is the dente-alveolar effect of functional appliances?

A
  • Distal movement upper dentition
  • Mesial movement lower dentition
  • Retroclination of upper incisors
  • Proclination of lower incisors
31
Q

What are the skeletal effects of functional appliances?

A

Degree of maxillary restraint and mandibular growth is small/varied
-> 1-2mm

  • might have happened anyway with growth- self correction
32
Q

When is the best time to use a functional appliance?

A

During growth
-> ideally at time of pre-pubertal growth spurt

33
Q

What are the different timing options in functional aplaiancce treatment?

A

– Early use – about 10 years old (2 phase- second on completion of permanent dentition)
– Later use – late mixed or early permanent dentition (1 phase treatment)

34
Q

What re the advantages and disadvantages of 2 phase treatment?

A

ADV:
Reduces trauma risk earlier
Improves appearance earlier (before starting high school)
Better compliance

DIS:
More treatment required- longer time
Can be difficult when teeth are exfoliating
Changes not maintained long term
Limited evidence to support

35
Q

What are the features of candidates for 1 phase functional appliance treatment?

A

Well aligned arches

Increased OB- forward growth rotation works better with this treatment

36
Q

What is Hawley bow used for in functional appliances?

A

Move incisors back

37
Q

What happens to patients who receive 1 phase functional appliance treatment as soon as this is complete?

A

Move onto fixed treatment- elastics may be required to hold things in place

38
Q

In what cases may a URA be used to tip teeth and fix class 2 div 1 malocclusion? (not commonly provided by specialists)

A

V. mild Class II or Class I

Overjet due to proclined and spaced incisors

Cases where the overbite is favourable

39
Q

In what malocclusion can use of a URA cause iatrogenic damage?

A

Class 2 div 2

40
Q

What are the features of a URA used to fix class 2 div 1?

A
  • Active: Roberts retractor 0.5mm in tubing (reclines incisors)
  • Retention: Adams cribs 6/6 0.7mm HSSW
  • Anchorage: Stops mesial to 3/3? (prevents canines coming forward before incisors come back)
  • Baseplate: Flat anterior biteplane (progressively trimmed to allow retraction)
41
Q

What is camouflage orthodontic treatment

A

Fixed appliance treatment to fix incisor relationship but not modify growth

-> done in older patients who have stopped growing, which are not severe enough for orthognathic surgery

42
Q

What is the goal of camouflage orthodontics in class 2 div 1 cases?

A

Reducing the overjet
-> may require extractions to give space or allow distal movement

43
Q

What teeth tend to be extracted in camouflage treatment?

A

4s
-> gives 7mm of space

7s- allows distal movement of 6s
-> half unit class 2 becomes full unit class 2

44
Q

Why may proclining retroclined incisors result in recession

A

Teeth moving forward but there is not alveolar bone present to cover (thin in this region)

45
Q

When is orthognathic surgery carried out?

A

Once growth is completed
-> Females 16-18
-> Males 18-20

46
Q

Are fixed appliances required in cases who also need orthognathic surgery?

A

Fixed appliances are usually always required in addition to surgery
-> can be done before to align and coordinate dental arches
-> can be done during or after too

47
Q

In what situation would orthognathic surgery be required?

A

Skeletal discrepancy is severe in A/P & or vertical direction

-> Usually involves mandibular surgery, but may also involve maxillary surgery

48
Q

What can maxillary impaction (osteotomy) be useful for?

A

Reducing showing of upper incisors and gingival

49
Q

Why may elastics be useful in addition to orthognathic surgery?

A

Holds teeth in closed position

BDS4 Orthodontics (14 decks)

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