Functional Appliances Flashcards
Often used in
Class II (–> Class I)
FAs change the skeletal pattern by adjusting…
Position of the mandible
Open
Forwards
Encourage condyles to move out of glenoid fosse to promote growth
FAs stretch … by …
stretch muscles by applying forces to bones and teeth
How does the position of mandible change
Bite is opened and jaw brought forward
Used on who? - twin blocks
What kind of growth
Class II Div I incisors with increased overjet
Class II molars
Actively growing
Aetiology of need for FA
86% mandibular retrusion
Assessment of skeletal pattern - methods
Clinical
Cephalometric analysis
Clinical assessment
Patient sitting upright
Look at profile
Bring mandible forward for posture test - instant improvement?
Cephalometric analysis involves measurement of?
ANB > 2 ?
Involves MMPA measurement
ANB > 2 means lower jaw is set back
Successful treatment requires
Patient motivation
Dentist enthusiasm and experience
Full time wear - overjet can be reduced in 9 months
Avoid FAs for
unmotivated patients
class I molar relationship
high MMPA - suggests open bite
Ideal timing depends on…
Stage of development
Dental - need at least first premolars through for fitting
Emotional status
Physical status
Measurement of standing height is plotted on
Height curve
Velocity curve
Peak growth occurs at ages
10-12 girls
11-13 boys
Which appliance to use?
Twin block - easier to get used to
Activators
Frankel
Twin block function and indication
Separate upper and lower
Midline screw to draw mandible forwards
Blocks fit together
Advantages of twin block
Aesthetic Full time wear Patient can move mandible Can expand upper arch and widen Integrate with fixed appliances at same time
Medium opening activator function and placement
Covers anterior lower teeth
Means lower posterior teeth are free to erupt which can help correct increased overbite
Cribs are fitted 64/46
Fixed functional appliance
Herbst
Fragile
Frankel appliance features
Soft tissue borne
Hold soft tissues away and shields alter soft tissue balance
Mode of action of FAs - different systems affected
Dental
Skeletal - movement exerts forces on soft and hard tissues
Soft tissues
Muscular
Dental mode of action of FAs
Opening bite so mandible moves downs and forwards
Some retroclination of upper incisors
Some proclamation of lower labial segment
Controlled eruption of lowers into class I
Skeletal mode of action of FAs
Forward movement of mandible
Headgear inhibits normal forward growth of maxilla
Mainly dento-alveolar
Maximises mandibular growth and encourage dente-alveolar changes to camouflage the malocclusion
Further reading
Introduction to orthodontics 4th ed chapter 9 - class II div I Chapter 19 - functional appliances
