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
Treatment Aims For Class II Div 1 Malocclusion
- Relieve crowding
- Reduce OB
- Reduce OJ
- Correct buccal segments relationships
Orthodontics ONLY treatment for Class II Div 1 Malocclusion should aim for?
- Dental camouflage
- Some mandibular growth
- Some maxillary growth inhibition
- Combination of above
When should patient be seen for treatment for Class II Div 1 Malocclusions?
- Mixed dentition to start growth modification 1 to 3 years before peak adolescent growth spurt
- Permanent dentition
Dental Characteristics for Class II Div 2 Malocclusion
- Maxillary central incisors overlapped on labial by maxillary lateral incisors
- Deep bite, minimal overjet
- Inverted maxillary occlusal plane with 2 occlusal levels: Anterior teeth overerupted and posterior teeth infraoccluded
- Mandibular curve of spee is exaggerated with extrusion of mandibular incisors
Soft Tissue Characteristics for Class II Div 2
- Straight to slightly convex facial profile
- Facial pattern is characteristically hypodivergent with relatively short LAFH, prominent chin point, flat mandibular plane and deep bite
- Orbicularis oris and mentalis muscle well developed and very active,
- Lower lip curl: Deep bite cause upper incisors to sit behind lower lip
Cephalometrics Findings of Class II Div 2 Malocclusion
- Mandibular form has a more acute gonial and mandibular plane angles
- Shorter LAFH
- Excessive overbite
- Lingual axial inclination of maxillary central incisors
What is Class II Subdivison?
Class II Molar relationship unilaterally instead of bilaterally (Classified as subdivision of the affected side)
Prevalence of Class II Div 2 in the population?
3% of populaiton
Aetiology of Class II Div 2 Occlusion?
- Strap-like lower lip may retrocline maxillary and mandibular
- High resting lip pressure against maxillary central incisors
Treatment Aims for Class II Div 2 Occlusion?
- Relieve crowding
- Decrease OB
- Correct buccal segment relationships
Characteristics favouring orthodontics ONLY treatment for Class II Div 2 Malocclusion
- Small ANB difference
- Growing patient
What steps are involved in the first stage of management of Class II patients?
- Correction of incisor flaring
- Molar relationship
- Crossbite
- Period of retention
What characteristics lead to increased risk of traumatic injury of upper incisors?
- Incompetent lips
- Overjet greater than 7 to 8mm
Timing of a Class II Referral
- 7-8 years old at time of eruption of permanent incisors
- Treatment once all permanent incisors have erupted
