Fixed appliances Flashcards
What are the components of a bracket?
- Bracket base
- Tie wing
- Archwire slot
- Bracket marker - to be placed distogingivally
What are the 3 tooth positioning variables controlled by the straight wire system?
First order - in//out or labio/lingual position
Second order - tooth angulation or mesio-distal tip
Third order - tooth angulation or torque
What bracket feature controls the first order?
The thickness of the bracket base
What bracket feature controls the second order?
The angulation of the archwire slot. Tooth tip is greatest for canines
What bracket feature controls the third order?
The angle the bracket base makes with the bracket slot, when viewed from the side
Where on the tooth should brackets be placed?
The centre of the bracket base should be positioned approximately over the midpoint of the long axis of the the clinical crown - known as the LA point
What is the definition of a fixed appliance?
An orthodontic appliance which is fixed to the teeth and can’t be removed by the patient
What are the mechanical principles of a fixed appliance?
- Applies mechanical force couple to the crown
- Allows precise control over the nature and direction of the forces applied
- Forces applied though interactions between components - archwires, auxialllaries, brackets
What kind of tooth movements occur with a FA?
Bodily
Rotation
Torque
What different materials can archwires be made from?
NiTi
Stainless steel
TMA (titanium molybdenum alloy)
Which different cross-sections do archwires have?
Round
Rectangular
What different materials can the brackets be made from?
Stainless steel
ceramic
plastic
What different types of brackets are there?
Twin
Self-ligating
What type of brackets are used in the BDH?
Twin stainless steel brakcets
Which type of archwire is needed to torque teeth?
Rectangular
Andrew’s 6 keys to normal occlusion (1972)
- Correct the molar relationship (to class 1)
- Correct the crown angulation
- Correct the crown inclination
- no rotations
- flat occlusal plane
- tight interproximal contacts - no space
What are the different types of FA
- Pre-adjusted edgewise appliance
2. Self-ligating appliance - Damon
What are the phases of fixed appliance treatment?
- Levelling and alignment
- Overbite reduction
- Overjet reduction
- Space closure
- Finishing procedures
How can you reduce overjet and close space?
- Stainless steel wires
2. Interarch elastics
When should you close space?
When the canines are in a class 1 occlusion
Initial alignment should be carried out with which wire?
0.012” or 0.014” NiTi. Flexible and high elastic limit
What is the choice of wire for overbite reduction?
Large diameter
Rigid
Stainless steel - round or rectangular
Which wire would you use for overjet reduction?
Rigid archwire of large dimensions
SS 0.019” x 0,025”
Which wire would you use for space closure?
Rigid archwire of large dimensions
SS 0.019” x 0,025”
Provides bodily control and prevents teeth tipping into space
