CLASS II DIV 1 Flashcards
What is the BSI definition of Class II Div 1?
- the lower incisor edges lie posterior to the cingulum plateau of the upper incisors
- there is an increased overjet
- the upper CIs are proclined or of average inclination
What % of malocclusions are Class II div 1?
15-20%
Why should class II div 1 malocclusions be treated?
- concerns regarding aesthetics
- concerns regarding dental health
What dental health risks are associated with a Class II Div 1 malocclusion?
trauma
What skeletal pattern is class II div 1 most likely associated with?
Class II skeletal pattern
What commonly causes a class II skeletal pattern?
retrognathic mandible most common
(maxillary protrusion less common)
What are the potential causes for the overjet in a Class II div 1 malocclusion?
- altered skeletal pattern
- tooth inclination
- combination of both
What is the normal value for SNA on a lateral cephalogram?
81 +/- 3
What is the normal value for SNB on a lateral cephalogram?
78 +/- 3
What is the normal value for ANB on a lateral cephalogram?
3 +/- 2
What is the average UI/MxP angle on a lateral cephalogram? (inclination of upper incisors)
109 +/- 6
What is the average LI/MxP angle on a lateral cephalogram? (inclination of lower incisors)
93 +/- 6
what is the normal LAFH/TAFH value?
55%
How do soft tissues normally present in a class II div 1 malocclusion?
- incompetent lips
- lower lip trap
How can an anterior oral seal be achieved in a normal occlusion?
- lip to lip seal by circum-oral musculature
- mandible postured to allow lips to meet
What is a lip trap?
lower lip drawn up behind upper incisors
What dental factors are associated with class II div 1 malocclusion?
- increased overjet
- overbite variations
- exacerbation of gingivitis due to parted lips
What are the occlusal features of a sucking habit?
- proclination of upper anteriors
- retroclination of lower anteriors
- localised AOB or incomplete AOB
- narrow upper arch
How can a sucking habit be managed?
- reinforcement techniques
- removable appliance habit breaker
- fixed appliance habit breaker
What management options are available for a patient with Class II Div 1 malocclusion?
- accept
- attempt growth modification
- simple tipping of teeth
- camouflage
- orthognathic surgery
How can you attempt to alter a patients growth modification with a class II div 1?
- headgear to restrain growth of the maxilla
- functional appliance
What removable functional appliances are available for patients with Class II div 1?
- twin-block
- activator/bionator
- Frankel (FRII) [soft tissue borne]
What fixed functional appliances are available for patients with Class II div 1?
Herbst
What is the aim of a functional appliance in class II div 1 patients?
aim to produce restraint of maxillary growth & encourage mandibular growth
What are the potential disadvantages of early functional appliance treatment of patients with Class II div 1?
- effects not maintained longterm
- treatment time increased
What are the potential advantages of early functional appliance treatment of patients with Class II div 1?
- improve appearance earlier
- reduce risk of trauma
- better compliance with appliance wear
Write the prescription for a functional appliance that retroclines anterior teeth?
Active = roberts retractor 0.5mm in tubing
Retention = Adams cribs 6/6 ).7mm HSSW
Anchorage = stops mesial 3/3
Baseplate = FABP (flat anterior bite plane)
When would orthognathic surgery be carried out?
When growth is complete
