Class II div 1 Flashcards
defintion class II div 1
BSI
The lower incisor edges lie posterior to the cingulum plateau of the upper incisors
There is an increased overjet
The upper central incisors are proclined or of average inclination
most common form of malocclusion
class II div1
why tx pt who has class II div 1 malocclusion/
2
concerns re aesthetics
concerns re dental health
* prominent incisors at risk of trauma esp if incompetent lips
overjet >9mm
* twice as likely to suffer trauma
* IOTN 5a
overjet >9mm
concerns
2
- twice as likely to suffer trauma
- IOTN 5a
aetiology of class II div1
4
- skeletal pattern - A/P, vertical, transverse
- soft tissues
- dental factors
- habits
A/P skeletal pattern for class II div 1
Usually associated with Class II skeletal pattern
Commonly due to a retrognathic mandible (smaller, set back)
* Maxillary protrusion less common
*Do see with skeletal class 1
Can get inc OJ with class 1 skeletal. Incisors are proclined
Very rarely see with skeletal class 3, but possible
Class 3 incisors proclined in a way that gives them inc overjet *
OJ due to
3
skeletal pattern
tooth inclination
combination of both
if see clinically proclination UI, retroclination LI
think
lower lip trapped behind U= finger suck habit
develop an eye for what is causing incisor relationships
if see clinically proclination UI, retroclination LI
think
lower lip trapped behind U= finger suck habit
develop an eye for what is causing incisor relationships
vertical skeletal pattern for class II div 1
variety
low, high, ave - no rule
often slightly steep plane angle
any associated with inc OJ
transverse skeletal pattern for class II div 1
no particular association with transverse problems
slight narrow maxilla sometimes
any associated with inc OJ
SNA
sella to nasion
A depth of concavity of maxilla
rep maxilla to anterior cranial base
SNB
sella to nasion
B concavity of mandible
represent mandible to anteiror cranial base
ANB
difference between A and B, how much class I or II pt is
MxP/MnP
maxillary plane, Frankfurt plane
* orbitale to porion- should be parallel to floor
compared to mandibular plane
LAFH/TAFH
nasion to anterior nasal spine
anterior nasal spine to menton (base of mandibular symphsis)
should be 55%
soft tissues in class II div 1
Lips often incompetent due to prominence of incisors and/or underlying skeletal pattern
Lower lip trap can be aetiological factor in increased overjet
* Can cause proclination and inc OJ more
* But also side effect of proclination
If lips incompetent then special effort needed to achieve an anterior oral seal
* Mentalis muscle habitual inc to get lower lip in from UI to close with upper lip to achieve ant oral seal
* May posture forwards
* Can assess when in dental chair
achieving an anterior oral seal
3
- Lip to lip seal by activity of circum-oral musculature
- Mandible postured to allow lips to meet
or
- Lower lip drawn up behind upper incisors
- Tongue placed forwards between incisors to lower lip
or
Combination of these
dental factors in class II div 1
Increased overjet (incisors proclined or average?)
Overbite varies
* hand in hand with inc or reduced face height
Can see good alignment, crowding or spacing
* Crowding - upper lateral tucked behind Ucentrals, cont to OJ
Molar relationship
* Variable
Habitually parted lips may lead to drying of gingiva and exacerbation of any pre-existing gingivitis
* lead to hyperplastic gingivitis, exposure to air inc, OH poor inc
NNSH
non-nutritional sucking habit
thumb, fingers, blanket, lip, combination