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