Fixed Appliance - Theory and Components Flashcards
What is theory behind FA - 4 steps?
- Bracket attached to tooth
- Interaction between bracket and arch wire
- Tooth movement
- Allow greater range of tooth movement
What are the 5 different types of tooth movement?
- Tipping - force on crown of tooth
- Bodily - movement crown and root
- Extrusion/ intrusion - toward occlusal plane/ up toward gingival margin
- Torque - tip crown generally stay same position - root moves
- Rotation
What movement can be achieved with FA?
All 5
What movements can be achieved with removal appliance?
Only tipping
What are problems with fixed appliances?
- Enamel demin/ caries
- Root resorption
- Soft tissue lacerations
- Periodontal problems
- Unwanted tooth movement
- Pulp devitalisation
Adv of FA?
Excellent tooth alignment in all 3 planes
Give informations re: bracket component
Pre-adjusted and made from stainless steel (can be ceramic or plastic)
Have tie-wings and slot (for arch wire)
Elastic module holds wire
What are the different shapes of arch wire?
Round wires - good for tipping teeth
Rectangular wires - bring full 3D movment as more contact in slot
Use round initially and then rectangular for final alignment and space closure
How apply bracket to teeth?
Base of bracket is stainless steel foil mesh
Etch and bond - composite applied to bracket base
Mechanical bond - strong enough to move teeth but weak enough to be removed w/o damaging teeth
What are aesthetic brackets?
Made from ceramic or placed lingually
Disadv plastic brackets?
Distort, discolour and fracture
Disadv ceramic brackets and when would you use?
Fracture - in use and on debond
Remnants left on teeth - need to use high speed
Abrasion of other teeth
Increased friction
cost
Only use lower arch if no overbite - mainly used upper arch only
When are lower and upper molar bands used?
Lower molar bands - single tube for arch wire - used to hook auxiliaries
Upper molar band - additional tube for headwear (not used for arch wire) - used to hook auxiliaries
When are separators used?
Between back molars - placed a week before to allow for easy placement of band
How to use molar bands?
Available different sizes - use smallest size available Use aquacem (GIC to bond)
What are molar tubes?
Alternative to bands - don’t need separation
Not as sturdy and difficult isolation moisture - more likely to debond
Can’t be used w/ headgear
What components make arch-wires different?
Functional, material, cross-section, shape
Difference between active and passive arch wire?
Active - move teeth w/ wire - light force and flexible –> NiTi
Passive - move teeth along wire - rigid –> SS (bodily movements)
Properties of NiTi wire?
Shape memory, super elastic, heat activated
What is an alternative to elastic modules and adv?
Wire ligatures (SS) or quick ties - accumulate less plaque
What is a self-ligating bracket?
Fixed appliance - don’t tie arch wire in w/ modules
Have gates to hold wire - specific instrument
What is an auxiliaries?
Elastics or springs
What are elastics and give examples?
Elastic bands that have different strengths and can be used in different directions
- Power-chain - used to close small space/ keep space closed
- Zing-string
- E-links - space closire
- Traction ligatures - modules on SS ligature
Give examples of springs?
Push coil/ coil spring - push teeth apart
Closing coil
What is in a fixed appliance kit?
Short probe Weingarts - for gripping arch wire Tucker Adams pliers - make bend arch wires Distal end cutters Crown shears - cutting end quick-ties Light wire pliers cutters - cutting light wire/ elastic
SWAT DCL
