2. Class II Division 1 Malocclusion Flashcards
What is the BSI definition of a Class II Div 1 malocclusion ?
Lower incisor edges lie posterior to the cingulum plateau of upper incisors.
Increased OJ.
Upper central incisors are proclaimed or of average inclination.
What % of malocclusions are Class II Div 1 ?
15-20%
What % of malocclusions are Class I ?
67-72%
What % of malocclusions are Class II Div 2 ?
10%
What % of malocclusions are Class III ?
3%
What are the reasons to treat a patient with Class II Div 1 ?
Aesthetics.
Trauma risk.
OJ greater than what are twice as likely to suffer trauma ?
> 9mm OJ (IOTN 5a).
What skeletal pattern is a Class II Div 1 associated with ?
Class II AP pattern.
What is the most common AP cause of a Class II Div 1 ?
Retrognathic mandible.
Maxillary protrusion is less likely.
Normal SNA value ?
81 +/- 3
Normal SNB value ?
78 +/- 3
Normal ANB value ?
3 +/- 2
Normal MxP/MnP value ?
27 +/- 4
Normal LAFH/TAFH value ?
55%
What are the four occlusal features of a sucking habit ?
Proclination of upper anteriors.
Retroclination of lower anteriors.
Localised AOB or incomplete OB.
Narrow upper arch (may see unilateral posterior cross bite).
What are the 5 management options for a Class II Div 1 ?
Accept.
Attempt growth modification.
Simple tipping of teeth.
Camouflage.
Orthognathic surgery.
Why is head gear used ?
Restrain growth of maxilla horizontal and/or vertically.
What are the two options for growth modification ?
Headgear.
Functional appliance.
Explain how a functional appliance works generally.
Utilize, eliminate, or guide the forces of muscles function, tooth eruption and growth to correct a malocclusion.
What is the name of the most common functional appliance used for a Class II Div 1 ?
Twin block.
Explain how a functional appliance caused growth modification in Class II Div 1 malocclusions specifically.
Aim to produce restraint of maxillary growth and encourage mandibular growth.
Mandible postured down and forwards.
What are two factors which will affect how well functional appliances help reducing malocclusions ?
Patient engagement.
Favourable growth age.
Describe the dento-alveolar changes seen using a functional appliance to correct a Class II Div 1 malocclusion.
Distal movement upper dentition.
Medial movement lower dentition.
Retroclination of uppers.
Proclination of lowers.
Describe the skeletal changes seen using a functional appliance to correct a Class II Div 1 malocclusion.
Small degree of maxillary restraint and mandibular growth - usually small 1-2mm.
But significant variation in response between patients.
At what age can functional appliances be used in 2 phase tx ?
10 years old - early use.
At what age can functional appliances be used in 1 phase tx ?
Early permanent or late mixed dentition - later use.
What are the potential disadvantages with early functional appliance treatment ?
Not maintained in long term.
Tx time increased.
Research shows little difference between early and later stage tx.
What are the 2 stages of 2 phase tx (using functional appliance) ?
Early functional appliance + retention.
Fixed appliances in early permanent dentition.
What are the potential benefits of early functional appliance tx ?
Improve appearance earlier.
Reduce risk of trauma.
Better compliance.
When are functional appliance beneficial to use in tipping of teeth ?
Very mild Class II or Class I.
OJ due to proclaimed and spaced incisors.
Overbite favourable.
What active component should be used in retroclining of anterior teeth on a URA ?
Roberts retractor 0.5mm in tubing.
+ Flat anterior bite plane.
Describe camouflage technique for Class II Div1.
XLA of upper 5s and retract upper centrals back with fixed appliances for OJ reduction.
When is orthognathic surgery carried out ?
When growth is complete.
Skeletal discrepancy is severe in AP or vertical direction.
