define class 2 div 1
The lower incisor edges lie posterior to the cingulum plateau of the upper incisors, there is an increase in overjet and the upper central incisors usually proclined or of average inclination
Why treat class 2 div 1
- aesthetic concerns
- incisors at risk of trauma
- overjet >9mm x2 as likely to suffer trauma
Associated skeletal pattern?
- usually class 2 (sometimes class 1 and possible with class 3 if incisors are proclined)
- usually due to retrognathic mandible
skeletal pattern (vertical)
- found with a range of vertical skeletal patterns
skeletal pattern (transverse)
- no particular assosiation
what can an overjet be due to
- skeletal pattern
- tooth inclination
- combination of both
What are normal ceph values
not class2, normal
- SNA= 81+/-3 (maxilla to anteiror cranial base)
- SNB= 78+/-3 (mandible to anterior cranial base)
- ANB= 3 +/-2 (difference between the two)
- MxP/MnP= 27 +/-4
- UI/MxP = 109+/-6
- LI/MnP = 93 +/-6
- LAFH/TAFH = 55%
ceph landmarks for upper/ lower anterior face height
- nasion
- anterior nasal spine
- menton
class 2 div 1 impact on soft tissues
- often incompetent lips
- can have lower lip trap
- if lips incompetent then special effort needed to achieve an anterior oral seal (mentalis muscle could be increased)
how is an anterior oral seal achieved
- lip to lip seal, mandible postured to allow lips to meet
- lower lip drawn up behind upper incisors, tongue placed forwards between incisors to lower lip
- combination of both
class 2 div 1 effect on dental factors
- increased overjet
- overbite varies
- can see good alignment, crowding or spacing
- molar relationship
- habitually parted lips may lead to drying of gingiva and exacerbation of any pre-existing gingivitis
occlusal features of sucking habit
- proclination of upper incisors
- retroclination of lower incisors
- localised or incomplete AOB
- narrow upper arch (possible unilateral posterior crossbite)
sucking habit tx principles
- stop habit (reinforcement, removable appliance habit breaker, fixed appliance habit breaker)
- allow spontaneous improvement
- treat residual malocclusion if required
management options for class 2 div 1
- accept
- attempt growth modification
- simple tipping of teeth
- camouflague
- orthognathic surgery
when would you accept class 2 div 1 malocclusion
- mildly increased OJ
- significant OJ but not unhappy?
- nb tx might be more difficult when older
- advice re mouthguard
in what ways can you attempt growth modification
- headgear
- try and restrain growth of maxilla horizontally and/or vertically - functional appliance
what do functional appliances do + aims
functional appliances utilize, eliminate, or guide the forces of muscle function, tooth eruption and growth to correct a malocclusion
success depends on favourable growth and compliant pt
Aims
- restraint of maxillary growth
- encourage mandibular growth
what malocclusions are functional appliances mostly used for
class 2 div 1
can use for 2 div 2 too
how do functional applinaces work
by posturing the mandible down and forwards, it encourages the mandible to grow
Types of functional appliance
Removable
- tooth-borne = (twin block or activator)
- soft tissue borne (Frankel 2, 2div2)
Fixed
- Herbst
what appliance is this
twin block
Therapeutic effect of functional appliances
Mostly dento-alveolar changes
- distal movement of uppers
- mesial movement of lowers
- retroclination of upper incisors
- proclination of lower incisors
Minor degree of skeletal changes
- RCTs indicate that degree of max restraint and mandibular growth is usually small
what ages are appropriate to use a functional appliance
- should be used during growth
- if possible coincide with pubertal growth spurt
- early use about 10 years old
- later use is late mixed or early permanent dentition
potential disadvantages of early treatment with functional appliance
- skeletal effects might not be maintained long term
- overall tx time increased
potential benefits of early treatment with functional appliance
- improve appearance earlier (e.g. for bullying reasons)
- reduce risk of trauma
- often better compliance with appliance wear
when could you use an URA for tipping of teeth
- v mild class 2 or 1
- OJ due to proclined and spaced incisors
- OB favourable
