Class II Div I Malocclusion Flashcards
What is a class II Div I malocclusion?
This is where the lower edge of the incisors occludes posterior to the cingulum plateau of the upper incisors
OJ is increased
Upper incisors may be proclined or of average inclination
Why do we tx class II Div I malocclusions?
Aesthetic reasons - profile concerns
Dental Health reasons - Inc OJ has risk of trauma (if OJ is >9mm then 2x risk of trauma)
IF pt has OJ >9mm what is their IOTN?
5a
What does an OJ of >9mm mean?
Inc trauma risk by 2x
What is the aetiology of a class II Div I malocclusion?
Skeletal pattern - AP relationship (usually class II skeletal base and class II incisors)
Habits
Dental Factors - inc OJ (proclined upper incisores)
Soft Tissues - incompetent lips, lip trap
What AP skeletal base relationship does a class II Div I malocclusion usually have?
Skeletal class II - the mandible is retrognathic and set further back
Why might a class II Div I pt have a class I skeletal base?
If pt has inc OJ, incisors are proclined and there is a lip trap
What is the ANB of a class II Div I pt?
> 4
What can the inclination of upper incisors be in class II Div I pts?
Can be >110 if proclined
Describe the soft tissue profile of a class II Div I pt
Lips can be incompetent = this is where when mentalis muscle is relaxed the lips do not meet
Incompetent lips can result in a lip trap which is where the upper incisors get trapped infront of the lower lip resulting in and INC OJ as the upper teeth are rpoclined and lowers retroclined
How do pts with incompetent lips achieve anterior oral seal?
They have to posture the mandible forwards to allow the lips to meet and the lower lip is pushed forward to get lip seal
OR
They posture the lower lip behind the incisors tongue is placed forwards between incisors and lower lip
OR COMBO OF ABOVE
What are the dental factors of a class II Div I pt?
Inc OJ
Can have retroclined or average inclination upper incisors
Can have inc OB
Molar relationship usually class II
Incompetent lips can lead to dry mouth which an exacerbate gingivitis
What habits can contribute to class II Div I malocclusion?
Dummy
Finger
Blanket
Lips
All of above
What does the effect of a habit depend on?
Duration and intensity of havbit - ifs pt habit is >6 hours a day then it will affect dental development, if habit more intense this also affects severity of effect of habit
What are the common features of a oral habit?
Proclination of the upper incisors
Retroclination of lower incisors
AOB (can be bilateral or unilateral)
Posterior crossbite
Narrow upper arch
Why is the upper arch narrowed with an oral habit?
The habit such as dummy sucking or finger sucking creates a vacuum effect and the cheeks are pulled in and the force of the muscles pushes against the teeth which an result in narrowing of the upper arch which can lead to crossbite
How do we stop a habit?
Postiv reinforcement at first - if pt wants to quit this is good starting point, use of nail polish, gloves etc to discourage habit
if not effective can use a URA if pt wants to stop with goalpost to prevent pt carrying out habit
If not effective can use a fixed appliance to prevent habit
if not successful within 2 months then likely pt doesn’t want to stop habit and no point trying any further until pt is ready
What are the tx options for a class II Div I pt?
Accept/Do Nothing
Growth Modification
Simple tipping of the teeth
Comoflague
Orthognathic surgery + orthodontics
When might we opt for accepting and doing nothing for class II Div I pt?
Class II DIv I is mild, skeletal discrepancy is mild
Minimal aesthetic problems
Pt is not bothered/doesnt want any tx done
Dental implications are minimal - OJ is mild so not a high trauma risk
What must we warn pts if they decide to accept class II Div I and do nothing?
Need to warn pt that in doing this is they in the future want tx it may be more difficult as growth stops and teeth are more difficult to move
When might we opt for growth modification of class II Div I pt?
If patient is still growing we have option to intercept and the aim is to POSTURE THE MANDIBLE FORWARDS AND PROMOTE MANDIBULAR GROWTH - this is possible as when we posture the mandible forwards we distract the condylar head out the glenoid fossa and stimulate it to grow more
We can use:
- head gear
- Frankel II
- Twin block appliance
What does headgear do for class II Div I pts?
Uses back of head as anchorage and aim is to restrict the maxilla growth but must be used 14 hrs a day for effect to occur and pt compliance must be high
What functional appliances can we use for Class II Div I pts and why?
Functional appliances aim to use, eliminate or guide muscle forces, tooth eruption d growth to correct the malocclusion
the aim of them is to posture the mandible forwards out the the glenoid fossa to encourage growth of the condyle
we can use:
- twin block
-frankel II
- Herbst
What is a twin block appliance?
This is an appliance that postures the mandible forwards to an edge to edge occlusion - the aim is to restrain the maxilla nd encourage mandible growth but this is often only bt 1-2mm and majority of effects via dente-alveolar compensation which is where there is retroclination of uppers, proclinatoron of lowers and the upper teeth are moved back and lower forwards
