Class II Div I Flashcards
How long should patients wearing headgear where it for and with how much force?
Px must wear for 14hrs with a force of 500g per side
How can digit sucking lead to class II div I?
- Proclination of upper anterior teeth
- Retroclination of lower anterior teeth
- Increased overjet
- Anterior open bite (usually asymmetric)
- Narrow upper arch +/- Unilateral posterior crossbite
What is a class II buccal relationship?
The buccal groove of the mandibular first permanent molar occludes posterior to the mesio-buccal cusp of the maxillary first molar
BSI Classification (british standards institute classifcation)
What is Orthognathic surgery?
Jaw surgery combined with fixed appliances
Usually mandibular
Define a Class II Div I
The lower incisor edges occlude behind the cingulum plateau of the upper incisors and the upper incisors are normally inclined or proclined
Always an increased overjet
What soft tissue factors contribute to the aetiology of class II div I malocclusion?
- Teeth erupt into a zone of equilibrium where they are controlled by the lips, tongue and cheek. If the lower lip does not control the upper teeth this can lead them to become proclined
- Increased mentalis activity leads to Retroclined lowers
Describe a pt that would require orthognathic surgery to treat class II div I
- Non growing px
- Severe Skeletal II (severe AP or VD)
- Poor facial appearance
Fixed appliances needed before, during & after surg
What teeth are traditionally removed in the upper and lower arch for camoflague tx of class II div I?
Upper 4s
Lower ideally none or 5s
Define functional appliance
What is the mode of action of a functional appliance?
What is the difference between myotonic and myo-dynamic?
Appliances that use forces generated by the oral and facial musculature to produce dental and skeletal changes
Forces are generated by stretching the facial musculature by holding the mandible in a postured position
Myotonic = Passive muscle stretching
Myo-dynamic = Muscular stretching during functional movement
Describe an ideal pt for camoflague tx of class II div I
- Mild – Mod Skeletal II pattern
- Px happy with facial profile
What is the gold standard functional appliance used in the UK?
Twin block
What dental changes would you expect to see with fixed appliances?
(Class II Div I Patient)
o Upper incisors retrocline
o Lower incisors procline
o Lower molars erupt mesially
o Upper molars tip distally
70% of changes observed are dental
What skeletal changes would you expect to see with fixed appliances?
(Class II Div I Patient)
Mandibular growth – 1-2 mm
*Maxillary restraint – 0.7mm
*Anterior repositioning of glenoid fossa
Give an example of a soft tissue bourne functional appliance
Frankel appliance
Describe what an ideal patient for orthodontic treatment for a class II div I malocclusion
- Well motivated (will wear)
- Actively growing
- Moderate – Severe A-P discrepancy
- Increased overjet
- Increased overbite
- Low FMPA (or normal)
- Reduced LAFH
- Lip trap px
- Proclined upper incisors & retroclined lower incisors
FMPA Frankfort-Mandibular Plane Angle / LAFH lower anterior face height
What is camoflague treatment for class II div I?
Accept the malocclusion and work around it
Normally XLAs in upper arch and use of fixed appliances (braces)
Can be done without XLA if there is adequate spacing
Normally only if there is mild/moderate skeletal II pattern
What would you say to a patient if they do not want treatment for their class II div I?
Explain risks (trauma) & give/advise mouthguard for contact sports
Why do we treat class II div I?
- For aesthetics
- There is an increased risk of trauma
- Psychological well being
- An Overjet of >9mm = IOTN 5a
Risk of trauma increases with increasing overjet
What are the treatment options for class II div I?
- No treatment
- Growth Modification (Interceptive)
- Camouflague
- Orthognathic Surgery (Comprehensive)
How does headgear help treat class II div I?
Force to maxilla to restrict A-P growth
Allows ‘catch up’ growth of the mandible
Can direct force to intrude or extrude molars to control vertical dimension
Name a passive and active tooth bourne functional appliance
Twin block (active)
Bionator (passive)
What skeletal changes would you expect to see with fixed appliances? (3)
(Class II Div I Patient)
o Mandibular growth at condyles (~1-2mm)
o Little restraint of the maxilla (~0.7mm)
o Glenoid fossa remodels to be more anterior
How may crowding lead to a class II div I malocclusion?
Crowding in upper arch (labial segment) leads to Proclination
Describe an poor patient for orthodontic treatment for class II div I malocclusion
- Poorly motivated
- Poor OH
- Non-growing (or towards end of growth spurt)
- Mild skeletal discrepancy
- High FMPA with reduced overbite
- Retroclined upper incisors
- Proclined lower incisors
What are the skeletal factors of the aetiology of class II div I malocclusion?
Most Px are skeletal II with a retrognathic mandible (80%)
Maxillary hyperplasia - large maxilla
LAFH most commonly reduced but varies
Vertical discrepancies- backwards growth rotations
retrognathic mand = small mand / LAFH = Lower anterior face height
What is the lower lip trap?
When the lips get trapped behind the upper teeth and cause proclination
What environmental factors can lead to class II div I?
Trauma to condyle
Habits - digit sucking
Dental factors (Crowding, pathological teeth migration forward leading to class II buccal segments)
Soft tissues, (mediated by the underlying skeletal pattern)
Lower lip trapping, hyperactive mentalis, and lip incompetence due to short upper lip.
Decreased muscle tone in cerebral palsy
Which values of a ceph would be different when considering a class II div I would be
Increased ANB
Reduced gonial angle
Normal, reduced or increased MMP angle and lower face height
Proclined upper incisors
Depending on the aetiology B-point may be reduced or A-point may be increased
State the incidence of trauma of different overjets
When would be accept a class II div I?
If this is accepted, what should be done?
*Acceptable aesthetics
*Patient not concerned
*Oral hygiene not good enough for treatment
*Overbite not a significant problem
Due to the high risk of trauma they should be advised to use a mouthguard for all contact sport.
