Removable appliances in orthodontics

Question 1

Advantages

Answer 1

Removable

Question 2

Disadvantages

Answer 2

Removable
Can only tip teeth 
Affects speech 
Poor tolerance in lower arch 
Intermaxillary traction not possible 
Inefficient for multiple tooth movements

Question 3

Mechanism

Answer 3

One point contact at tooth crown can tip tooth

Question 4

If fully controlled movement is desired then

Answer 4

Attachment to tooth is needed e.g via fixed appliance to give 3d control

Question 5

Components of design (ARAB)

Answer 5

Active components
Retention
Anchorage
Baseplate and Biteplanes

Question 6

Active components - in decreasing order of preference

Answer 6

Moving teeth with removable appliance
Springs - palatal and buccal
Screws
Elastics

Question 7

Properties of springs - Force of spring depends upon

Answer 7

Thickness of wire
Length of wire
Amount of deflection

Question 8

Palatal finger spring

Properties

Where is it not well placed

Answer 8

0.5mm/0.6mm wire
Coil near acrylic (increases length) 
Coil on side away from direction of movement
Can use on any teeth
Not good on buccally placed teeth

Question 9

Screws - adjustment

Answer 9

Quarter turn = 0.2mm

1 turn/week = just <1mm a month

Question 10

Indications for screws

Answer 10

Moving blocks of teeth

Can move tooth and use for retention

Question 11

Screws used for buccal movement - mechanism

Answer 11

Move upper labial segment

Question 12

Elastics

Answer 12

Poor control

Rarely used

Question 13

Retention - definition

Answer 13

MB/DB undercuts - 0.25mm

Anterior retention using C-clasps and southend clasps

Question 14

Anchorage - definition

Answer 14

Control of unwanted tooth movement

Additional anchorage via palatal vault

Question 15

How is anchorage maintained

Answer 15

Light forces
Only moving one tooth per side
Large anchor unit 
More teeth included in appliance design 
Headgear

Question 16

Problems with headgear

Answer 16

Co-operation

Safety –> catapulting accident - eye injury risk

Question 17

Eye injury risks

Answer 17

Infection
Antibiotic control
Sympathetic ophthalmitis
Headgear safety measures are essential

Question 18

Baseplates+Biteplanes

Answer 18

Connects components
Carries passive wirework
Additional anchorage
Carries Biteplanes

Question 19

Types of biteplanes and function

Answer 19

Anterior biteplane 
- flat- reduces overbite 
- inclined - retains functional appliance tx and proclines lower incisors 
Posterior biteplane 
- frees the occlusion

Question 20

Cases which can be treated with RA

Answer 20

Disimpaction of first molars 
Class III Ant Xbite
Posterior Xbite 
Space maintenance 
Overbite correction

Question 21

Assessment criteria

Answer 21

Talk to patient 
Assess for signs of wear
Assess progress, measure changes 
Assess OH 
Assess retention 
Check if active component still active 
Reassess anchorage 
Document findings and plan