Fixed Orthodontic Appliances

Question 1

What are fixed appliances?

Answer 1

An appliance which is fixed to the teeth and cannot be removed by the patient.

Question 2

When do we use fixed appliances?

Answer 2

Correct of mild to moderate skeletal discrepancies
Alignment of teeth
Correction of rotations
Centreline correction
Overbite and overjet reduction
Closure of spaces/creating spaces
Vertical movements of teeth

Question 3

What are the components of fixed appliances?

Answer 3

Archwire
Brackets
Elastomeric modules
Molar tubing
Molar band
Anchorage components
Force generating components

Question 4

What materials can brackets be made from?

Answer 4

Metal- SS (most common), CoCr, Ti, Au
Polymers
Ceramics

Question 5

What is used to bond ortho bands to molar teeth?

Answer 5

Glass ionomer

Question 6

What must be done first before placing orthodontic bands on molar teeth?

Answer 6

Create space- place separators

Question 7

What material is used to bond brackets to teeth?

Answer 7

Composite- micro mechanical retention.
- can use self etch or etch and then bond.

Question 8

Why is Nickel Titanium used as the first type of wire in fixed ortho appliances?

Answer 8

Flexible
Light continuous forces
Shape memory- returns to original shape, cannot bend.
Higher friction than stainless steel

Question 9

Why is stainless steel used as the second type of wire in fixed ortho appliances?

Answer 9

Used to slide teeth easier because it has low friction.

Question 10

What is the function of elastomeric ligatures?

Answer 10

Keeps the wire within the bracket.

Question 11

What is the function of bumper tubing?

Answer 11

Used where there are large extraction spaces- this will create space to alleviate crowding.

Used to prevent soft tissue trauma in the event that the wire pops out of the molar bands.

Question 12

What is the purpose of stainless steel arch wire with spring?

Answer 12

Makes space for teeth- i.e. instanding laterals.

Question 13

What are the force generating components in fixed appliances?

Answer 13

Sliding mechanics
- elastic power chain
- NiTi coils- to push teeth apart or close space
- Intra-oral elastics
- Active ligature

Question 14

What is an elastomeric power chain?

Answer 14

Runs from the tube hook to the brass wire hook.
Used to close spaces.

Question 15

What are Nickel Titanium coil springs?

Answer 15

Used to push teeth apart.

Question 16

What is the purpose of intraoral elastics?

Answer 16

Distal or mesial movement of teeth.
i.e. in class II cases- move the lower teeth distally and upper teeth medially.

Question 17

What is anchorage?

Answer 17

Resistance to unwanted tooth movement.

Must plan this carefully to avoid unnecessary complications.

Question 18

What types of anchorage can you get?

Answer 18

Simple- using teeth within the same arch, as well as anchorage components- elastomeric power chain used to pull one tooth that is linked to another tooth with a higher root surface ratio.

Compound- linking groups of teeth together as a unit, increases the root surface area.

Reciprocal- one tooth is linked to another similar tooth- same root surface area, so both teeth will move together since both forces are balanced.

Question 19

What is absolute anchorage?

Answer 19

Using temporary anchorage devices

Question 20

Give an example of a type of temporary anchorage device?

Answer 20

Non osseointegrating mini screw
- Inter-radicular TAD
- Palatal TAD

Question 21

What devices can be used to maintain cortical anchorage?

Answer 21

Transpalatal arch
Nance palatal arch

Question 22

What can be used for inter- maxillary anchorage?

Answer 22

Intermaxillary elastics

Class III elastics- run from lower canine to the upper molar

Class II elastics- run from upper canine to lower molar.

Question 23

What is retention?

Answer 23

Maintaining the final tooth position with a passive orthodontic appliance.

Designed to prevent relapse.

Question 24

What malocclusion features have a high relapse potential?

Answer 24

Instanding upper laterals
Diastemas
AOB
Rotations
Palatally ectopic canines
Proclination of lower incisors

These patients would benefit from a fixed orthodontic retainer.

Question 25

What types of retainer are available for patients?

Answer 25

Hawley conventional retainer
Vacuum formed retainer
Fixed orthodontic retainer

Question 26

What do you want to check with a lingual bonded retainer at each check up?

Answer 26

Check composite is still firmly adhered to tooth surface.

Ensure no calculus despots present around composite or wire.

No sharp bits of wire.

Wire hasn’t fractured.