Class 2/1 Flashcards
What is the definition of class 2/1? And what is the aetiology?
the lower incisor edge occludes posterior to the cingulum plataeu of the upper incisors and the upper incisors are wither at a normal inclination or proclined and over jet is increased
Skeletal
Soft tissue
Dento alveolar : crowding
Local factors: digit habit
Is the jet reduced, average or increased in class 2/1?
it is increased, the normal value is 2-3mm
What is the incidence of class 2/1 incisor relationship? And why do they need treatment?
22% (2–30%)
Aesthetics
Function considerations
Dental health consideration
Reduced the risk of trauma to uppers
what is the skeletal aetiology of class 2/1?
skeletal: large maxilla and small mandible or posterior articulation of the mandible within the gelnoid fossa, vertical and lateral relationships are normal, sometime retrognathic mandible
What type of profile do class 2/1 usually have?
convex
What are the soft tissue aetiology for class 2/1?
lip morpholgy: short upper lip and decreased tone
Lip competance
Anterior oral seal: created by tongue to lower lip or lower lip to palate
tongue
where should the lower lip be relative to the tips of the upper incisors?
the lower lip should cover the incisal third
When is it more likely to be seen where an anterior oral seal is created by the tongue being placed against the lower lip?
when there is an increase in vertical proportion
What is a rare cause of class 2/1?
where the lower lip is so muscular that it retroclines the lower incisors
What are the treatment options for class 2/1?
camofluage
growth modifcation
correct underlying skeletal abnormaility
When would you treat a CLass 2/1 with camofluage?
when there is a mild skeletal discreapancy and you can tip the upper incisors back to reduce the overjet
WHat would you use for growh modifcation?
functional appliances
How effective is growth modifcation for class 2/1?
mitchell
not very effective, the changes acheived from the use of funcional appliances were not maintained long term and usuing functional appiances protracts the treatment
What are the treatment methods for treating class 2/1?
upper removable appliances
functional appliances
fixed appliances
Orthognathic
When would you use an URA?
overjet <8mm
proclined upper labial segment
3/3 are mesially angulated
class 1/mild class 2 skeletal pattern
may need to carry out extrcations
When would you use a functional appliance in class 2/1?
one stage treatment
two stage followed by fixed appliances
When would you use one stage functional appliances?
when the overjet >8mm
well aligned arches
class 2 molar
pubertal growth
When would you use a a two stage functional appliances? (functional appliances followed by FA)
when the overjet is>8mm
crowding
class 2 molar
When would we use fixed appliances alone?
multiple tooth movements bodily movement of upper labial segment correction of rotations space closure arch co-ordination
When would we consider orthognathic treatment for people with class 2/1?
when there is a severe class 2 skeletal patten and tooth movement and growth modification alone would not correct the malocclusion
People with severe class 2 skeletal pattern how would you use growth modifications?
restrain the maxilla using head gear
promote mandibular growth with functional
An overjet of 6mm has a trauma incidence of how much?
22%
An overjet of 9mm has a trauma incidence of how much?
24%
An overjet of >9mm has a trauma incidence of how much?
44%
What is the aetiology of class 2/1?
Skeletal
Soft tissue
Dento alveolar
Associated habits
What is the dento alveolar cause of class 2/1?
The upper teeth are so crowded that they push the upper incisors out of the arch and the teeth are then pushed labially
What is the stability of the overjet dependant upon?
Soft tissues
What type of growth of the mandible is modern advantageous in class 2/1 cases?
Forward growth
Why is backward growth in a class 2 less favourable?
- AP discrepancy will worsen with growth
2. Increase in lower facial height will reduce likelihood do competent lips at the end of treatment
