Removable Appliances

Question 1

What is the mode of action for removable appliances?

Answer 1

They tip teeth around a centre of resistance.

Question 2

What tooth movements can be achieved with a removable appliance?

Answer 2

1. Tipping of teeth, eg correction of single tooth crossbite.
2. Allow differential eruption of teeth using biteplanes.
3. Distal movement of buccal segments with ‘en masse’ appliance and headgear.
4. Distal movement of upper buccal segment/mesial movement of lower buccal segment with functional appliance.

Question 3

What is the acronym used to design a URA? and explain its meaning.

Answer 3

A.R.A.B

Active components (e.g Z spring)
Retention (e.g Adam’s cribs)
Anchorage (e.g Acrylic baseplate)
Baseplate (with/without midline screw for expansion)

Question 4

What are the advantages of using a URA?

Answer 4

• cheap.
• simple and easy to adjust.
• OH easier than fixed appliances.
• can move teeth in blocks.

Question 5

What are the disadvantages of using a URA?

Answer 5

• patient compliance is needed.
• can only move a few teeth at a time.
• tipping movements only.
• poorer retention in lower arch.
• difficult to treat rotations.
• affects speech.

Question 6

What are the common uses for removable appliances?

Answer 6

1. Space maintainers.
2. Retainers.
3. Expansion.
4. Bite planes.
5. Functional appliances.
6. Support distal movement +/- HG.
7. Digital sucking habit.

Question 7

How can you tell if a patient has been wearing their removable appliance?

Answer 7

1. The pt can take it in and out easily.
2. The pt can speak normally.
3. Erythema (redness) of the palate and gingiva.
4. Signs of wear on the appliance.
5. No excess saliva.

Question 8

What service should be given to patients upon fitting a removable appliance?

Answer 8

1. How to take in and out.
2. When/how often to wear it.
3. How to clean it.
4. What to do it if breaks. (Inc. costs)
5. What to expect when wearing it (saliva, speech, discomfort).
6. Use of pain relief.
7. Keep seeing GDP regularly.