Class 2 Division 2 Flashcards
What is the definition of class 2 division 2
The lower incisors occludes posterior to the cingulum plateau of the upper incisors
The upper incisors are retroclined
The overjet is reduced but can also be increased
Third most common incisor relationship (5-18%)
What can the aetiology of class 2 div 2 be split into
skeletal
soft tissue
dental features
What is the skeletal AP aetiology
Usually associated with a mild or moderate class 2 base but it is possible for it to occur on a class 1 or class 3 base
Often have a small under-developed mandible (retronghatic)
What is the vertical skeletal aetiology
Reduced FMPA typically
Often associated with a forward rotational pattern of growth of the mandible
Often have a prominent chin (aka progenia)
Usually have a low LAFH ratio
What is the soft tissue aetiology
high resting lower lip line secondary to the decreased lower face height and this can retrocline the incisors due to the active mentalis
Marked labiomental fold
High masseteric forces which can make space closure difficult so must make careful extractions decisions
Can sometimes see flaring of the laterals vs retroclination of the centrals
Why are the laterals spared from being retroclined
Upper 2’s may end up being normal inclinication/proclined as their shorter clinical crown means they escape the effect of the lower lip
Can result in a lip trap tendency
What are the dental features in the aetiology of class 2 div 2
- Retroclination of the upper centrals
- Upper 2s often crowded- rotated and may be either normal or proclined
- Reduced arch length- exacerbates crowding
- Lateral incisors have poor cingulum which can result in lack of an interocclusal stop producing an overbite
Why are class 2 division 2 prone to a deep overbite
Lateral incisors often have poor cingulum which can result in a lack of interincisial occlusal stop which can lead to a deep overbite
Increased interincisal angle
Why are class 2 division 2 more prone to impacted canines
55% have more than 1 dental anomaly associated
If they have got peg laterals/microdontia in their laterals then this can influence the canine eruption pattern leading to impacted canines
What are the reasons for treatment of class 2 division 2
Aesthetic concern
Dental health concerns
Traumatic overbite = IOTN DHC 4f
What are the treatment options dependant on
o Severity of malocclusion
o Age and motivation of px
o Dental health
o Patient concerns
What are the treatment options
accept malocclusion
growth modification
camouflage
orthognathic surgery
When is accepting the malocclusion the best option
Good treatment option when there is acceptable aesthetics, patient is not concerned or not suitable and the overbite is not a significant problem
Who is growth modification best suited for
growing patient in their growth sport
mild/moderate class 2 pattern
What does growth modification do
Convert the class II div 2 to Class II div 1
Followed by fixed appliances to detail occlusion
What is the function of the functional appliances
to procline the upper incisors
What is the common appliance used for class 2 division 2
modified twin block - uses springs/screws to help procline the incisors
sometimes used in combination with sectional fixed appliance to help with improving inclination of the labial segment
What is camouflage
Accepting the underlying skeletal base relationship and aiming to treat to class 1 incisor relationship
Who is camoulfage suitable for
Suitable for patients who are past their growth spurt and who have a mild/moderate class II skeletal pattern
What appliance does camouflage use
fixed
What does stable correction of class 2 division 2 require (camouflage)
overbite reduction
correction of inter-incisial angle (reduction)
Why is it important to reduce the overbite in class 2 division 2 cases
overbite will relapse if not corrected
What are the indications for orthognathic surgery
When a patients malocclusion is too severe for orthodontics alone
Non-growing patient
Profile concerns
What is done prior to orthognathic surgery
Pre-surgical orthodontics
Increase the overjet and convert to class 2 division 1
Can take up to 18 months
Why is orthodontics used post surgery
Usually there is a 3 point landing where there is only contact on incisors and terminal molars resulting in lateral open bites
Settled orthodontics is used to close lateral open bites and guide the occlusion together, can take 6 months
Aiming for class 1
What can effect stability post treatment
Future face growth can affect stability
Rotated laterals and deep overbite can relapse
Long term bonded retention usually required
When are deep overbites best corrected
when px is growing
What is appliances are best used for deep overbites
Growth modification with functional appliance if AP discrepancy
URA with FABP
