Class II Malocclusion Flashcards
Angle’s Class II Definition
Lower first permanent molar is distal to the upper first permanent molar by at least the width of half a cusp
How is Class II subdivided
Based on maxillary incisor inclination
Class II Div 1
Max anteriors are proclined and a large OJ is present
Class II Div 2
Max anteriors are retroclined and a deep OB is present
Prevalence of Class II Div 1 and 2 malocclusion
Div 1: 1 in 4 in asian males
Div 2: Very little
Aetiology of Malocclusions
Genetic + Environmental factors
Genetic predisposing factor of Class II
Inherited growth patterns of mandible that causes the chin to grow downwards and backwards
Environmental predisposing factor of Class II
1
- Digit sucking/Persistent non-nutritive sucking beyond the age of 4
- Imbalance of forces from oral soft tissues (eg. tongues and lips)
- Early loss of maxillary second deciduous molars - mesial migration, rotation and tipping of permanent maxillary first molars
General characteristics of Class II (skeletal + dental)
- Maxillary skeletal excess (Size)
- Maxillary dental excess (Proclination)
- Mandibular skeletal deficiency (Size)
- Mandibular dental deficiency (Retroclination)
Class II Div 1 Soft Tissue profile
4
- Convex
- Lower lip trap
- Shorter upper lip - failure in lip closure
- Acute nasolabial angle
Class II Div 1 Skeletal features
- Protrusive Max
- Retrognathic Man
- Shorter Man length
What does skeletal involvement indicate about the case
Increase in degree of difficulty and less favourable prognosis
Class II Div 1 Dental Features
6
- Protrusive Max Dentoalveolus
- Retrusive Man Dentoalveolus
- Class II Molar relationship
- Increased OJ
- Deep OB
- V-shaped upper arch (narrow at canines and broad at molars)
Class II Div 1 Lat Ceph
Various combinations of:
- Maxilla and teeth are anterior in relation to cranium
- Max teeth are anterior in normally positioned max
- Man is normal size but posteriorly position
- Man is underdeveloped
- Man teeth are posteriorly placed in a mandible that is in a normal position
Class II Div 2 Soft Tissue profile
9
- Straight to slightly convex
- Hypodivergent
- Short lower face height
- Prominent chin point
- Flat mandibular plane
- Deep bite
- Deep labiomental fold
- Well-developed and active orbicularis oris and mentalis muscle –> lingually inclined upper centrals
- Lower lip curl –> deep bite causing upper incisors to sit behind the lower lip
Class II Div 2 Dental features
6
- Max centrals lingually inclined and overlapped on the labial by max laterals
- Deep OB
- Minimal OJ
- Broad upper arch (usually)
- Inverted Max occlusal plane (2 occlusal planes): Overerupted anteriors and infraoccluded posteriors
- Exaggerated curve of Spee with extrusion of mandibular incisors
Class II Div 2 Lat Ceph
- Acute gonial and mandibular plane angles
- Short LAFH
- Excessive OB
- Lingual axial inclination of maxillary central incisors
What is a unilateral class II molar r/s called
subdivision
What components make up an orthodontic diagnostic statement
Dental + Skeletal + Cause/Aetiology + Growth Component
Eg. Class II Div 1 Malocclusion on a Class II skeletal base due to retrognathic mandible in an adolescent patient
What makes children at risk of suffering trauma to their upper incisors
Children with incompetent lips and an increased overjet greater than 7-8mm
What are the objectives of the first stage of Class II Management
Early correction of incisor flaring, molar relationship and crossbite
+ Retention
Why is early correction important in the management of class II patients
- Simplifies treatment in the second stage
- Maxillary incisor retraction minimises danger of traumatic injury and improves abnormal lip position
What is DAC used for
To mask underlying AP skeletal discrepancies
What happens prior to dental surgery in DAC patients
Dental Decompensation must be done first
Timing of Class II referral
7-8 years old during eruption of permanent incisors
Types of Class II treatment modalities
- Growth modification (interceptive treatment on growing patients) eg. Twin block functional appliance
- Comprehensive ortho
- Orthodontic-Orthognathic surgery - after halt of growth
