Class 2 Div 1 Flashcards
Types of malocclusion
Class 2 div 1 - 15-20%
Definition of Class 2 div 1
- lower incisor edges lie posterior to the cingulum plateau of upper incisors
- increased OJ
- upper central incisors are proclined or average inclination
Why treat class 2 div 1?
- aesthetics
- dental health
- prominent incisors at risk of trauma especially if incompetent lips
- OJ > 9mm twice as likely to suffer trauma
- OJ > 9mm, IOTN 5a
What includes in aetiology and features?
- skeletal pattern (A/P, vertical, transverse)
- soft tissues
- dental factors
- habits
Skeletal pattern of class 2 div 1 (A/P)
- associated with class 2 sk pattern
- due to retrognathic mandible
- less common to have maxillary protrusion
- can happen in skeletal class 1
- rarely in class 3
OJ might be due to?
- sk pattern
- tooth inclination
- combination of both
Sk pattern - Vertical
- found in association with a range of vertical sk pattern
Sk pattern (transverse)
- no particular association with transverse
Normal values for SNA
81 +/- 3
Normal values of SNB
78 +/- 3
Normal values of ANB
3 +/- 2
Normal values of UI/MxP
109 +/- 6
Normal values of LI/ MnP
93 +/- 6
Lateral ceph labelling
Normal values for LAFH/ TAFH
55%
Presentation of Soft tissues
- lips are often incompetent due to prominence of incisors and/ or underlying Sk pattern
- lower lip trap can be aetiological factor in increased OJ
- if lips incompetent, then special effort needed to achieve anterior oral seal
Achieving an anterior oral seal
- lip to lip seal by activity of circum-oral musculature
- mandible postured to allow lips to meet - Lower lip drawn up behind upper incisors
- tongue placed forwards between incisors to lower lip - combi of both
Dental factors of Class 2 div 1
- increased OJ - incisors proclined/ average
- Overbite varies
- good alignment, crowding or spacing
- molar relationship
- parted lips may lead to drying of gingiva and exacerbation of any pre-existing gingivitis
Sucking habits
- thumb
- fingers
- blanket
- lip
- combination of all
- NNSH - non nutritive sucking habits
** depends on duration and intensity
Occlusal Features of Sucking Habits
- proclination of upper anteriors
- retroclination of lower anteriors
- localised AOB/ incomplete OB
- narrow upper arch
- may see unilateral posterior crossbite
How to stop habits?
- Stop habit
- reinforcement
- removable appliance habit breaker
- fixed appliance habit breaker - allow spontaneous improvement
- treat residual malocclusion if required
Types of Management Options
- Accept
- Growth Modification
- Simple tipping of teeth
- Camouflage
- Orthognathic surgery
Accept conditions
- mildly increased OJ
- significant OJ but not unhappy
- will future tx options be more difficult in the future?
- advise on mouthguard
Growth Modification
- Headgear to try and restrain growth of maxilla horizontally and vertically
- functional appliance
What is Functional appliance?
- utilize, eliminate, guide the forces of muscle function, tooth eruption and growth to correct malocclusion
- used mostly in class 2 div 1
Types of functional appliances
Removable
- tooth borne: twin block, activator/ bionator
- ST borne: Frankel 2
Fixed
- Herbst
Twin Block Appliances
GM with Functional appliances
- produce restraint of maxillary growth and encourage mandibular growth
- depends on favourable growth and enthusiastic pt
Therapeutic effect of Functional Appliances
Mostly dento-alveolar changes
- distal movement of upper dentition
- mesial movement lower dentition
- retroclination of upper incisors
- proclination of lower incisors
Minor degree of skeletal changes
- degree of maxillary restraint and mandibular growth is usually small (1-2mm)
When to use functional appliances?
- during growth
- early use about 10 yrs old (2 phase tx)
- later use for late mixed/ early permanent dentition (1 phase)
Disadvantages of early tx
- early skeletal effects from functional appliance/ headgear therapy not maintained in long term
- overall tx time increased, 2 phase tx
1. early functional appliances + retention
2. fixed appliances in early perm dentition
Benefits of Early tx
- improve appearance earlier from teasing
- reduce trauma
- better compliance with appliance wear
When to use simple tipping of teeth?
- simple URA has limited role in tx of increased OJ
Unless
- very mild class 2/1
- OJ due to proclined and spaced incisors
- OB favourable
- after specialist assessment
Retroclining anterior teeth
Camouflage with fixed appliances
- reduce OJ
- may need upper arch extractions to give space/ distal movements
Orthognathic surgery
- when growth is complete
- sk discrepancy is severe in A/P or vertical direction
- usually involves mandibular surgery, but may involve maxillary surgery
- fixed required before, during and after surgery
