class 2 div 2 malocclusion Flashcards
definition
lower incisors occlude posterior to the cingulum plateau of the upper incisor
upper incisors retroclined
OJ reduced but can also be increased
incidence
literature dependent 5-18%
broad etiological features
skeletal
soft tissue
dental
pathology e.g. condylar problems
AP skeletal pattern
usually associated with a mild/mod class 2 base can also be class 1 or 3
vertical skeletal pattern
typically reduced FMPA
often associated with a forward rotational pattern of growth of the mandible
prominent chin “progenia”
soft tissue features
high resting lower lip line - secondary to reduced LFH, retroclines U incisors marked labio-mental fold high masseteric forces - ortho space closure problems - ext cases can be difficult
dental features
upper laterals
retroclined U and L incisors
reduced arch length - exacerbates crowding
increased OB - traumatic or non-traumatic
increased inter-incisal angle
L incisors may occlude with the U incisors or palatal mucosa
U incisors may “strip” lower labial gingivae
OJ usually reduced
class 2 buccal segments
dental features - upper laterals
shorter clinical crown and poor cingulum
escape the effect of the L lip or trap L lip
often crowded
mesio-labially rotated
may be normal or proclined depending on their position relative to the lip line
normal inter-incisal angle
135 degrees
association with developmental dental anomalies
50% have a form of congenital dental anomaly, 33% with impacted canine
55% 1 or more developmental anomaly
- 20% impacted canine
- 15% lateral incisor microdontia
why tx?
aesthetics - dental or profile
dental health concerns - traumatic OB - IOTN DHC 4f
what do the tx options depend on?
severity of the malocclusion
age and motivation of patient
dental health
pts concerns
tx options
accept
growth modification
camouflage
orthognathic tx
indications to accept
acceptable aesthetics
pt not concerned
pt not suitable for ortho tx
OB not a significant problem - not traumatic
indications for growth modification
growing pt - adolescent growth spurt mild to mod class 2 skeletal base
when is the adolescent growth spurt?
boys 14 +/- 2 years
girls 12 +/- 2 years
using fct appliances
convert into class 2 div 1 - procline U incisors detail occlusion with fixed appliances
what fct appliance is used?
modified twin block
components of a modified twin block
spring at front - expansion labial segment aligner (ELSA), activated chair side, procline upper incisors
screw - anterior screw section (rely on pt compliance)
upper sectional fixed appliance - but aesthetic result quickly so pts lose motivation and aren’t bothered about fixing the rest of the malocclusion
camouflage
accept the underlying skeletal base relationship and aim to tx to class 1 incisor relationship
why is a careful extraction decision needed in camouflage?
space closure difficult in low angle cases
indication for camouflage
mild to mod class 2 skeletal pattern
what needs to be achieved with fixed appliances for a stable correction?
OB reduction
correction (reduction) of interincisal angle
what will relapse if not corrected?
OB
