Fixed Ortho

Question 1

What are Andrews 6 keys (treatment goals)

Answer 1

1. Tight approximate contacts with no rotations
2. Class 1 incisors
3. Class 1 molars
4. Flat occlusal plane or slight curve of spee
5. Long axis of teeth have slight medial inclination (except lower incisors)
6. The crowns of the canines back to molars have lingual inclination

Question 2

What are the advantages of fixed appliances?

Answer 2

3D control
Complex tooth movements - rotations, intrusion etc
Control of root
Less dependant on compliance

Question 3

What is a disadvantage of fixed appliances?

Answer 3

Lack of anchorage
Risk of iatrogenic damage

Question 4

What materials can a bracket be made of?

Answer 4

Metal - stainless steel, cocr
Polymers
Ceramic - more aesthetic, destructive to upper incídalo edges when on lower incurs

Question 5

How much space is required Inter proximal y for molar band placement?

Answer 5

1mm

Question 6

How to separators work?

Answer 6

Absorb water and compress pdl

Question 7

What are molar bands bonded using?

Answer 7

GI cement

Question 8

What features are included on bracket prescription?

Answer 8

Torque
Tilt (medial angulation)
In/ out (bucal/ lingual position)

Question 9

What wavelength of light is the light cure?

Answer 9

440- 480 um

Question 10

How are brackets attached to teeth?

Answer 10

Using prescription for positioning

Bonded using composite

Question 11

What are the types of arch wires and when are they used?

Answer 11

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.

Question 12

What is the purpose of force generating components?

Answer 12

Sliding teeth, uses the energy stored in the elastic or spring

Question 13

What are some examples of force generating components?

Answer 13

Elastic power chain - lose their force quickly, used to close space

NiTi coils - used to create space

Intra oral elastics

Active ligatures

Question 14

What is anchorage?

Answer 14

Resistance to unwanted tooth movement
Based on newtons 3rd law - every force has an equal but opposite reactionary force

Question 15

What are the 3 types of anchorage?

Answer 15

Simple
Compound
Reciprocal

Question 16

What devices can be used to achieve anchorage in fixed appliances?

Answer 16

Cortical anchorage
Temporary archorage devices - Inter radicular/ palatal
Nance palatal arch
Inter maxillary anchorage (elastics)

Question 17

What are the main risks of fixed ortho?

Answer 17

Decalcification
Root resorption
Relapse

Question 18

What features have high relapse potential?

Answer 18

Diastema/ space closure
Rotations
Palatally ectopic canines
Procaína tino of lower incisors
Anterior open bite
In standing upper laterals

Question 19

How long is average course of fixed ortho?

Answer 19

18-24 months

Question 20

How long is an average course of fixed ortho for hypodontia/ orthognathic cases?

Answer 20

24-30 months

Question 21

What type of movement is achieved with NiTi wire?

Answer 21

In out

Question 22

What type of movement is achieved with stainless steel wire?

Answer 22

Bodily movement
Torque/ tilt

Question 23

What is reciprocal anchorage?

Answer 23

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

Question 24

What is simple anchorage?

Answer 24

When one tooth with greater alveolar support is used to move another tooth with lesser support

Question 25

What is compound anchorage?

Answer 25

Anchorage where the resistance provided by more than one tooth with greater support is used to move teeth with less support