Fixed Ortho Flashcards
What are Andrews 6 keys (treatment goals)
- Tight approximate contacts with no rotations
- Class 1 incisors
- Class 1 molars
- Flat occlusal plane or slight curve of spee
- Long axis of teeth have slight medial inclination (except lower incisors)
- The crowns of the canines back to molars have lingual inclination
What are the advantages of fixed appliances?
3D control
Complex tooth movements - rotations, intrusion etc
Control of root
Less dependant on compliance
What is a disadvantage of fixed appliances?
Lack of anchorage
Risk of iatrogenic damage
What materials can a bracket be made of?
Metal - stainless steel, cocr
Polymers
Ceramic - more aesthetic, destructive to upper incídalo edges when on lower incurs
How much space is required Inter proximal y for molar band placement?
1mm
How to separators work?
Absorb water and compress pdl
What are molar bands bonded using?
GI cement
What features are included on bracket prescription?
Torque
Tilt (medial angulation)
In/ out (bucal/ lingual position)
What wavelength of light is the light cure?
440- 480 um
How are brackets attached to teeth?
Using prescription for positioning
Bonded using composite
What are the types of arch wires and when are they used?
Stainless steel - working arch wire to slide teeth (low friction), formable
Nickel titanium - flexible, provides light continuous force, higher friction than SS, shape memory.
Start with light flexible, then full size working archwire for sliding teeth.
What is the purpose of force generating components?
Sliding teeth, uses the energy stored in the elastic or spring
What are some examples of force generating components?
Elastic power chain - lose their force quickly, used to close space
NiTi coils - used to create space
Intra oral elastics
Active ligatures
What is anchorage?
Resistance to unwanted tooth movement
Based on newtons 3rd law - every force has an equal but opposite reactionary force
What are the 3 types of anchorage?
Simple
Compound
Reciprocal
What devices can be used to achieve anchorage in fixed appliances?
Cortical anchorage
Temporary archorage devices - Inter radicular/ palatal
Nance palatal arch
Inter maxillary anchorage (elastics)
What are the main risks of fixed ortho?
Decalcification
Root resorption
Relapse
What features have high relapse potential?
Diastema/ space closure
Rotations
Palatally ectopic canines
Procaína tino of lower incisors
Anterior open bite
In standing upper laterals
How long is average course of fixed ortho?
18-24 months
How long is an average course of fixed ortho for hypodontia/ orthognathic cases?
24-30 months
What type of movement is achieved with NiTi wire?
In out
What type of movement is achieved with stainless steel wire?
Bodily movement
Torque/ tilt
What is reciprocal anchorage?
Refers to 2 malposed units when the dissipation of equal and opposite forces tend to move towards a more normal occlsuion (2 move towards each other) - eg intermaxillary elastics
What is simple anchorage?
When one tooth with greater alveolar support is used to move another tooth with lesser support
