Class II Malocclusion Flashcards
Angle defined Class II Malocclusion as?
Lower first permanent molar is distal to the upper first permanent molar by at least the width of half a cusp
BSI Class II/1 Incisal Classification
Proclined maxillary incisors with overjet >4mm
BSI Class II/2a Incisal Classification
Retroclined maxillary centrals
Proclined/retroclined laterals
Normal or reduced overjet
BSI Class II/2b Incisal Classification
Retroclined maxillary centrals
Proclined/retroclined laterals
Increased overjet
Class II Div 1 Incisal Relationship are usually associated with?
- Deep overjet
- Retrognathic mandible
Class II Div 2 Incisal Relationship are usually associated with?
- Deep overbite
- Deep labiomental fold
- Reduced LAFH
What is the Aetiology of Class II Malocclusions? - General Factors
- Hereditary: Inherited growth patterns of mandible such that chin grows downwards and backwards
- Congenital
- Environment
- Predisposing metabolic climate and disease
- Nutritional deficiency
- Abnormal pressure habits: Digit sucking beyond age of 4
- Posture
- Trauma and accidents
What is the Aetiology of Class II Malocclusions? - Local Factors
- Anomalies of number: Supernumerary or missing teeth
- Anomalies of tooth size and shape
- Abnormal labial frenum: Mucosal barriers
- Premature loss of or prolonged retention of primary teeth: Early loss of maxillary Es can result in mesial migration, rotation and tipping of maxillary 1st molars
- Delayed eruption of permanent teeth
- Abnormal eruptive path
- Ankylosis
- Dental caries
- Improper dental restorations
General Characteristics of Class II Relationship
- Maxillary skeletal excess
- Maxillary dental excess
- Mandibular skeletal deficiency
- Mandibular dental deficiency
Characteristics of Class II DIv 1 Soft Tissue Profile
- Convex facial profile
- Lower lip trapped behind upper incisors (Significantly retrognathic mandible + Increased overjet)
- Acute nasiolabial angle (Protrusion of maxilla but angle is affected by nasal form itself)
Characteristics of Class II Div 1 Skeletal Profile
- Convex facial profile
- Significantly retrognathic mandible + Increased overjet
3.Protrusion of maxilla
Skeletal involvement indicates increase difficulty and more unfavourable prognosis
Characteristics of Class II Div 1 Dental Relationship
- Protrusive maxilla dentoalveolus and/or retrusive mandibular dentoalveolus
- Proclined or normal inclination upper incisors
- Increased overjet
Characteristic of Class II Div 1 Cephalometrics
Maxilla and teeth anterior wrt. cranium
Maxillary teeth are anterior in a normally positioned maxilla
Mandible is of normal size but posteriorly positioned
Mandible is underdeveloped
Mandibular teeth are posteriorly placed on a mandible that is normal position
Various combinations of above
Prevalence of Class II Div 1 Malocclusion?
20% of population
Aetiology of Class II Div 1
- Class II Skeletal base
- Digit sucking
- Soft tissues such as short upper lip or lower lip trap