Class 2 Division 1 Malocclusions Flashcards
What is the BSI definition of a Class 2 Div 1 Malocclusion
- The lower incisor edges lie posterior to the cingulum plateau of the upper incisors
- There is an increased overjet
- The upper central incisors are proclined or of average inclination
How prevalent are different malocclusion forms?
Class I 67-72%
Class II div 1 15-20%
Class II div 2 10%
Class III 3%
What are the reasons for treating class 2 div 1?
- Concerns re aesthetics
- Concerns re dental health
–> Prominent incisors at risk from trauma especially if incompetent lips
Why does a >9mm OJ score an IOTN of 5a?
Due to risk of trauma
-> twice as likely
What factors are involved in the aetiology of class 2 div 1 patients?
Skeletal pattern
– A/P, Vertical, Transverse
Soft tissues
Dental factors
Habits
What are the features of the AP skeletal pattern in class 2 div 1?
Usually associated with a class 2 skeletal relationship
-> Commonly due to a retrognathic mandible (maxillary protrusion less common)
*Seen in class 1 if proclined incisors, can be seen in class 3 too
What causes the OJ in class 2 div 1 patients?
Tooth inclination- proclination of uppers/retroclination of lowers
Skeletal pattern
Combination of both
What are the features of Vertical and Transverse relationships in class 2 div 1 patients?
Vertical- can be associated with high or low angle
-> often there is an increased FMPA
Transverse- no particular association with transverse issues (maxilla may be narrower)
What are the normal cephalometric values in a class 1 patient?
SNA = 81 +/- 3
SNB = 78 +/- 3
ANB = 3 +/- 2
MxP/MnP = 27 +/- 4
UI/MxP = 109 +/- 6
LI/MnP = 93 +/- 6
LAFH:TAFH- 55%
Why are maxillary and Frankfort plane often used interchangeably?
Often parallel in most patients
In which ways can soft tissues contribute to OJ in class 2 div 1 patients?
Lip traps can cause proclination of upper anteriors
What are the ways in which a patient with incompetent lips can create an oral seal?
– Lip to lip seal by activity of circum-oral musculature
– Mandible postured to allow lips to meet
or
– Lower lip drawn up
behind upper incisors
– Tongue placed forwards
between incisors to lower
lip
–> Combination of these
What are the dental features of a class 2 div 1 malocclusion?
Increased overjet
Varied OB
Molar relationship- usually class 2
Can have good alignment, crowding or spacing
May have hyper plastic gingivitis due to parting of the lips causing drying
Why may crowding contribute to class 2 div 1 malocclusions?
Laterals can be tucked in behind centrals causing them to procline more
Which sucking habits (Non-necrotive) may lead to class 2 div 1 maolocclusion?
Thumb
Fingers
Blanket
Lip
-> Combination
What are the occlusal features of a sucking habit?
Proclination of upper anteriors
Retroclination of lower anteriors
Localised AOB or incomplete OB
Narrow upper arch (may see unilateral posterior crossbite)
Why may a patient with a sucking habit have an asymmetrical AOB?
They only suck one thumb
What can be used to stop a sucking habit?
Wearing a glove
Putting something on thumb
Positive Reinforcement
Removable appliance habit breaker
Fixed appliance habit breaker (with goal post)
What can occur if a patient stops habit quickly
Spontaneous improvement
What are the issues with using habit breakers in patients beyond 9 years old?
Disruption to occlusion as root formation could be reduced
What are the different management options for a class 2 div 1 maolocclusion?
- Accept
- Attempt growth modification
- Simple tipping of teeth URA
- Camouflage
- Orthognathic surgery
In what cases may accepting a class 2 div 1 be considered?
If patient does not want treatment
Mildly increased OJ
Low IOTN
Minimal aesthetic concern
What should you warn a patient about their untreated class 2 div 1 malocclusion in the future?
Future treatment will be more difficult
Trauma risk is higher
What can be used to attempt growth modification in class 2 div 1 cases?
Head gear (uncommon)
Functional appliances
How does head gear work
Head gear- restrains maxillary growth (unsure about evidence for effect long term)
Back of head is used as anchorage support- force is applied to distalise upper molars and intrude them (good for AOB/reduced OB)
14 plus hours per day required
What is the purpose of functional appliances?
Functional appliances utilise, eliminate, or guide the forces of muscle function, tooth eruption and growth to correct a malocclusion
-> used mostly in class 2 div 1 cases (sometimes div 2)
How do Functional appliances work?
Postures mandible forwards and uses masticatory muscles to pull back upper teeth with it
Condyles grow more as they move out of the glenoid fossa
-> aims to restrain maxillary growth and promote mandibular growth
What are the types of functional appliances that can be used for class 2 div 1?
Removable- twin block (most widely used)- clasps onto teeth and holds teeth in edge-to-edge position
Activator/bionator- less commonly used
Frankel 2 (soft tissue borne)- postures mandible and allows expansion of the maxilla
Fixed (Herbst)- pistons and connecting rods (more reliable but prone to breakage)
What is the main issue with removable orthodontic appliances?
Compliance issues
What is the dente-alveolar effect of functional appliances?
- Distal movement upper dentition
- Mesial movement lower dentition
- Retroclination of upper incisors
- Proclination of lower incisors
What are the skeletal effects of functional appliances?
Degree of maxillary restraint and mandibular growth is small/varied
-> 1-2mm
- might have happened anyway with growth- self correction
When is the best time to use a functional appliance?
During growth
-> ideally at time of pre-pubertal growth spurt
What are the different timing options in functional aplaiancce treatment?
– Early use – about 10 years old (2 phase- second on completion of permanent dentition)
– Later use – late mixed or early permanent dentition (1 phase treatment)
What re the advantages and disadvantages of 2 phase treatment?
ADV:
Reduces trauma risk earlier
Improves appearance earlier (before starting high school)
Better compliance
DIS:
More treatment required- longer time
Can be difficult when teeth are exfoliating
Changes not maintained long term
Limited evidence to support
What are the features of candidates for 1 phase functional appliance treatment?
Well aligned arches
Increased OB- forward growth rotation works better with this treatment
What is Hawley bow used for in functional appliances?
Move incisors back
What happens to patients who receive 1 phase functional appliance treatment as soon as this is complete?
Move onto fixed treatment- elastics may be required to hold things in place
In what cases may a URA be used to tip teeth and fix class 2 div 1 malocclusion? (not commonly provided by specialists)
V. mild Class II or Class I
Overjet due to proclined and spaced incisors
Cases where the overbite is favourable
In what malocclusion can use of a URA cause iatrogenic damage?
Class 2 div 2
What are the features of a URA used to fix class 2 div 1?
- Active: Roberts retractor 0.5mm in tubing (reclines incisors)
- Retention: Adams cribs 6/6 0.7mm HSSW
- Anchorage: Stops mesial to 3/3? (prevents canines coming forward before incisors come back)
- Baseplate: Flat anterior biteplane (progressively trimmed to allow retraction)
What is camouflage orthodontic treatment
Fixed appliance treatment to fix incisor relationship but not modify growth
-> done in older patients who have stopped growing, which are not severe enough for orthognathic surgery
What is the goal of camouflage orthodontics in class 2 div 1 cases?
Reducing the overjet
-> may require extractions to give space or allow distal movement
What teeth tend to be extracted in camouflage treatment?
4s
-> gives 7mm of space
7s- allows distal movement of 6s
-> half unit class 2 becomes full unit class 2
Why may proclining retroclined incisors result in recession
Teeth moving forward but there is not alveolar bone present to cover (thin in this region)
When is orthognathic surgery carried out?
Once growth is completed
-> Females 16-18
-> Males 18-20
Are fixed appliances required in cases who also need orthognathic surgery?
Fixed appliances are usually always required in addition to surgery
-> can be done before to align and coordinate dental arches
-> can be done during or after too
In what situation would orthognathic surgery be required?
Skeletal discrepancy is severe in A/P & or vertical direction
-> Usually involves mandibular surgery, but may also involve maxillary surgery
What can maxillary impaction (osteotomy) be useful for?
Reducing showing of upper incisors and gingival
Why may elastics be useful in addition to orthognathic surgery?
Holds teeth in closed position
