class II div 1 Flashcards
What is the BSI definition of Class II 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
What are the prevalence rates for different types of malocclusion (incisor relationship)?
Class I - 67-72%
Class II div 1 - 15-20%
Class II div 2 - 10%
Class III - 3%
Why is it important to treat a class II div 1 malocclusion?
Aesthetic concerns
Risk of trauma to prominent incisors (especially if incompetent lips)
Increased likelihood of trauma if overjet >9mm
What is the normal SNA value?
81º +/-3
What is the normal SNB value?
78º +/-3
What is the normal ANB value?
3º +/-2
What is the normal FMPA?
27º +/-4
What is the normal UI/MxP value?
109º +/-6
What is the average LI/MnP value?
93º +/-6
What is the average LAFH/TAFH?
55%
Describe the soft tissue characteristics often seen in class II div 1 malocclusions
Incompetent lips due to prominent incisors or underlying skeletal pattern
Achieving an oral seal may require lip to lip seal or lower lip drawn up behind incisors with tongue placed forwards between incisors to lower lip
What are some dental factors associated with class II div 1 malocclusion?
Increased overjet
Variable overbite
Varying alignment (crowding or spacing)
Potential exacerbation of gingivitis due to habitually parted lips
Describe the occlusal features of sucking habits in class II div 1 malocclusion
Proclined upper anteriors
Retroclined lower anteriors
Localised anterior open bite or incomplete overbite
Narrow upper arch with the possibility of unilateral posterior crossbite.
What are the management options for class II div 1 malocclusion?
Accepting the condition - if mildly increased overjet or if the patient is not unhappy
Attempting growth modification - with headgear or functional appliances
Simple tipping of teeth - using removable appliances
Camouflage
Orthognathic surgery
Define functional appliances for growth modification.
Functional appliances for growth modification utilize, eliminate, or guide the forces of muscle function, tooth eruption, and growth to correct a malocclusion
They aim to produce restraint of maxillary growth and encourage mandibular growth.
What are the therapeutic effects of functional appliances?
Dento-alveolar changes such as:
- distal movement of upper dentition
- mesial movement of lower dentition
- retroclination of upper incisors
- proclination of lower incisors.
May also be minor skeletal changes, although the degree of maxillary restraint and mandibular growth is usually small.
Describe the potential benefits of early treatment for class II div 1 malocclusion
Improving appearance earlier
Reducing trauma risk
Better compliance with appliance wear
Define baseplates in orthodontics.
Baseplates are used to provide support and anchorage for orthodontic appliances.
What is the role of a flat anterior biteplane in orthodontic treatment?
To reduce overbite
Describe when orthognathic surgery is typically performed
Orthognathic surgery is carried out when growth is complete.
On what skeletal base class can you see a class II div 1 malocclusion?
Usually on a class II
Can see it on class I
Very rarely on class III but still possible
How does a skeletal base most commonly cause a class II div 1 malocclusion?
Usually due to a retrognathic mandible
What contributes to an overjet?
Skeletal pattern
Tooth inclination
Usually a combination of both
What are the treatment principles of habits?
Stop habit - with reinforcement, removable appliance habit breaker or fixed appliance habit breaker
Allow spontaneous improvement
Treat residual malocclusion if required
Using ARAB, design a URA to retrocline the anterior teeth
A - Roberts retractor 0.5mm HSSW with 0.5mm ID tubing
R - Adam’s clasps on 6s 0.7mm HSSW
A - mesial stops on 3s
B - self-cure PMMA and FABP (OJ+3mm)
At what stage should functional appliances be used?
Early use (about 10) - 2 phase treatment of early functional appliance and fixed appliances in early permanent dentition
Later use - late mixed dentition or early permanent dentition, 1 phase treatment
What are the potential disadvantages of early treatment with functional appliances?
Early skeletal effects not maintained in the long term
Treatment time increased
Research shows little difference between those treated early and later on
What are the types of functional appliances?
Removable:
- tooth borne - either twin block or activator/bionator
- soft tissue borne - Franker (FR II)
Fixed:
- Herbst
