Fixed and removable appliances: General

Question 1

List the different types of orthodontic appliances

Answer 1

Comes in two categories:
• Removable
• Fixed

From there, they can have three mechanisms of action:
• Active
• Passive
• Functional

Question 2

List the advantages (3) and disadvantages (4) of fixed appliances

Answer 2

Advantages
• No issues of non- compliance
• Treats more complex malocclusions
• Allows for more movement

Disadvantages:
• More expensive
• Harder to clean around
• Need for special equipment
• More complex

Question 3

List the advantages (4) and disadvantages (3) of removable appliances

Answer 3

Advantages:
• Simple design
• Easy to clean
• Low cost
• No need for special equipment

Disadvantages:
• Issue of non- compliance
• Treats only minor causes of malocclusion
• Restricted to only simple ortho cases

Question 4

List the three basic parts seen in all removable appliances

Answer 4

• Retentive components
• Base plate
• Active components

Question 5

Retentive components

• Explain retentive components
• Where they need to be placed
• Three types of retentive components

Answer 5

Explain retentive components:
• Holds the appliance in the mouth by reinforcing its anchorage

Where they need to be placed:
• Anteriorly (usually labial bow and ball ended clasps)
• Posteriorly (usually Adam’s clasp)

Three types of retentive components:
• Clasps: Adam’s clasp, ball clasps, c clasps
• Labial bow/ arch
• Acrylic framework/ base plates

Question 6

Base plate
Explain the base plate in terms of:
- What it is made of and how it is made
- Its purpose (3)
- Modifications

Answer 6

What it is made of and how it is made:
· The base plate is made from heat curing or self- curing acrylic resin

Its purpose (3):
· It reinforces the clasps and active components
· It increases the surface area for greater retention
· It reinforces anchorage: anterior teeth are anchored with the posterior teeth, and together they are all anchored against the palate

Modifications:
· They can be modified to have bite planes to reduce a deep bite

Question 7

Active components
List the purpose of active components

List the different types of active components (5)

Answer 7

Purpose:
· Provide teeth movement / desired effect

Different types of active components (5): 
· Springs
· Labial bows
· Expansion screws
· Bite planes 
· Tongue crib

Question 8

active component of “springs” in terms of:

• Composition
• Purpose
• The types of springs

Answer 8

Composition:
· Made of stainless-steel wires

Purpose: 
· Help "tip teeth" (when a single force is applied against the crown of a tooth)

 The types of springs:
· Finger spring, Z-spring, T-spring, canine retractor and short labial arch

Question 9

Describe the active component of “labial bows” in terms of its active and passive components

Answer 9

• Active components help with minor overjet reduction and anterior space closure
• Passive components are for retention

Question 10

State the purpose of the active component of “bite planes

Answer 10

· Stops posterior occlusion
· This can help correct a deep bite as the posterior teeth will begin to erupt more to try and occlude, eventually correcting the bite
· Effective for the growing patient

Question 11

State the purpose of the active component of “tongue cribs”

Answer 11

• Prevents tongue from sitting between anterior teeth

* Used when tongue positioning is the causes of an open bite