Malocclusion Class 2 Div 1 Flashcards
Class 2 div 1
-Lower incisors lies above cingulum plateau of upper central incisors.
- upper central incisors are at normal inclination or proclined
- increased Overjet
Incidence
20%
Aetiology of class 2 div 1
- Skeletal factors
- soft tissue factors
- Dento alveolar factors
- habits
Skeletal pattern class 2 div 1
- sk Class 2 div 1 76%
- sk Class 2 div 2 15%
- sk class 1 Less than 30%
- sk class 3 less than 5 %
Sk Factor - AP
- large maxilla
- small mandible
- posterior articulation of mandible with glenoid fossa
Sk Factors vertical and lateral.
-All types ( Average, increased , reduced face height)
- facial asymmetry possible
Soft tissues factors
-lip morphology - length or tone
- lip competence definition : ( lower lip resting height)- short upper lip or low lower lip
- anterior oral seal
- tongue
Lip competency definition
Lips together at rest without muscular activity
Lip competency describe?
-Resting height of lower lip should ideally cover Incisal third upper 21-12
- lip competence seems to improve with age due to growth and social acceptability.
Habitual competency
Contraction of mentalis muscle alllow lips to meet.
Why do lips matter in tx?
- Markedly incompetent lips may cause Relapse of overjet
- Ditto a low lower lip line.
- short upper lip may give an un attractive smile.
Anterior oral seal
- Tongue to lower lip
- lower lip to palate
Why do we need AOS?
Swallowing
Dento alveolar factors
Crowding
Does not cause CLASS 2 div 1
Habit
Digit sucking
Treatment why?
- Asthetic considerations
- functional considerations
- dental health considerations
- To reduce the risk trauma to upper incisors in children > 10 years
Incidence of incisors trauma
Greater than 9 mm 50%
Treatment consideration
- dental Camouflage
- Growth Modification (restrained maxillary growth and more mandibular growth)
- correction of underlying sk problem
Pt should be fully informed and involved in decision making process
Treatment Aims
- Relieve crowding
- Align the teeth
-Reduce overbite - Reduce overjet
- close spacing
- co ordinate upper and lower arch
Treatment methods
-Upper removable appliance
- Functional appliance
- Fixed appliance
- Joint orthodontic / orthodonathic (surgical approach)
Favourable feature for orthodontic treatment
- small ANB
- no dental compensation
- growing pt
- cessation of habit if present
- greater component of OJ being proclination of ULS
Upper removable appliance
Clinical indication
-Overjet less than 8mm
- Proclined upper labial segment
- mesially angulated 3s’
Removable appliance for which cases?
- Class 2 div 1 incisor relationship
- upper incisor crowding
- canine mesially angulted
- lower incisor lie anterior to upper root centroid
-OJ less than 8mm
-Proclined upper labial segment
Removable appliance Aim
- Relief of crowding
- overbite reduction
- Overjet reduction
Functional appliance:
- one stage treatment
- Two stage treatment folllowed by fixed appliance therapy with or without XTs.
When do we use Functional Appliance ? One stage
-One stage treatment
- Overjet more than 8mm
- well aligned arches
- class 2 molar relationship
-prepubertal
Functional appliance:
Clinical indication ?
- Overjet more than 8mm
- crowding
- class 2 molar relationship
Stage two Fixed appliances
Clinical indications
- Multiple tooth movement
- bodily movement of upper labial segment
- correction of rotations
- space closure
- Arch co ordination
Orthognathic treatment when?
- Severe Class 2 sk pattern
- tooth movement alone unable to achieve aims in terms of aesthetic, functions and stability
- non growing pt
General feature of SK
- 76% SK 2 base , If SK1 incisors relationship due to habit
- cranial base angle high - mandibular rethrognathia
- longer cranial base - prognathic Maxilla
- may have small or large maxilla
- average lower facial height.
Normal cranial base angle 120-125
General feature of Soft tissue
Incompetent lips
Lower Lip trap
Short upper lips
General dental features
- class 2 incisor relationship
- increased Overjet
- OB deep incomplete
- buccal segment can be class 2 or 1
- mandibular position : ensure pt not habitually posturing, treat to centric
- facial growth - variable, usually favourable growth
Which component of upper removable appliance reduce over jet?
- Robert’s retractor
