URA Design + Intro to Fixed appliances Flashcards
2 most common situations for use of RA
- crossbite correction
- arch expansion
What is the first appliance made by Edward Angle and what is it based off?
Limitation?
E-arch (expansion arch)
based off Fauchards appliance
it could only tip teeth
What is Edward Angle’s pin and tube appliance? Pro and con?
vertical tubes soldered to bands on teeth - tubes were engaged with pins
Good 3D control, was able to develop the first Mc in fixed applianced
Very difficult to adjust - pins had to be re-soldered in new positions to adjust
What is Angles’ Ribbon-arch appliance? Give advantage?
same principle except for this there was a cut tube in which a wire was placed behind to deliver the force
much easier to work with as you just had to bend the eire and place back in the slot
(introduces wire)
What is edgewise appliance and advantage?
same as ribbon arch except appliance turned 90 degrees and wire inserted ‘edgewise’ into appliance, giving better control of tooth movement when compared to ribbon arch
–> basis for modern bracket
Movements by Edgewise appliance
- 3D
- tipping
- bodily movements
- torquing
Limitations of Edgwise appliance
- high forces (wire thick)
- time consuming to bend specifically for all 3D movements for each tooth
What principle of Angle did Tweed (student) refute and why?
Non-extraction principles
- Tweed found that a number of cases had relapses after the appliance was removed, but when exos done outcome lasted longer
Begg Appliance. advantage and disadvantage
modified version of Angles ribbon-arch bracket - turned upside down and used very work-hardened wire
–> more springly
con: can only use thin round wires –> taking away the bodily movement aspect –> fixed by adding auxillary springs
- one part of spring into bracket the other engaged the wire, once the spring pulled on the wire, it would upright the bracket
Advantage of adding auxillary springs to Begg appliance
very efficient
low force
Why were bands so common in past ortho?
- prior to adhesive dental materials
- now we only sometimes used bands for molars
Advantage of Ni-ti wire in ortho?
shape memory - either super elastic or heat activated
Larry Andrews 6 keys to normal occlusion
- ideal class I molar relationship - same as Angle but also D surface of mx 1st molar occludes with M surface of MB cusp of md 2nd molar (caused by angle of upper 1st molar, if too little then no room for upper 2nd pm to occlude)
- crown angulation - crowns of all teeth need to be angled correctly for all teeth to fit tgt
- crown inclination - all crowns have to have correct B-L inclination & angle
- No rotations
- Tooth spacing - need tight contains and no spacing
- Want a flat occlusal plane (small curve of spee)
Andrews Straightwire Appliance. Advantage
all the required tooth movements were incooporated into brackets shapes and could just run a straight wire through to fit into the 6 keys of normal O’
bends were incorporated into brackets so no bending of wires needed, simple and easy to use
Most popular appliance today
straightwire appliance
